Glossary of TPRBIO
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- Protiens that are to be secreted pass through what series of organelles?
- ER->Golgi->secretory vesicles-> Extreior through exocytosis
- Where in the cell whould the M6P receptor be transcribed?
- Transcription is the reading of genes in DNA by RNA polymerase to make mRNA. All transcription takes place in the nucleus.
- The transport of proteins to the lysosomoes require?
- Vesicle movement from the rough ER to the Golgi
- At the placenta, CO2 should normally?
- Diffuse from the fetal side to the maternal side.
- Which of the following chambers of the fetal heart supply blood to the systemic circulatory system?
- Left ventricle and right ventricle. Since blood mixes in the fetus b/w the pulmonary artery and the aorta throught the ductus arteriosus, both ventricles pump blood to the systemic curculation. In the adult, only the left ventricles pump blood to the systemic circulation. Atria deliver blood only to teh ventricles, not to the systemic circulation.
- Across which of the following cell types would the inward diffusion of water be most pronounced under normal conditions?
- One of the main fuctions of the large intestines is the reabsorption of salt and water from forming feces. The epithelial cells in the large intestine are best designed for inward movement of water.
- If cells were placed in a hypotonic medium and the cells were permeable to water and Mg2+ then the cells would most likely have?
- Decrease in Ca2+ (inside the cell) concentration by intake of water. If the medium is hypotonic, it contains fewer solutes than the interior of the cells. Either water will move into the cells or solutes will leave the cells to equalize the osmotic pressure inside and outside of the cell.
Placement of erythrocytes in a hypertonic solution will cause it to Shrivel.
- Active transport requires?
- Conversion of ATP-> ADP and lot of mitochondria in the cytoplasm.
- Key precesses in the production of energy that occurs in the mitochondrion?
- 1) Citric Acid cycle
NO GLYCOLYSIS!!!(OCCURS IN CYTOPLASM)
- In hypotonic environment (ex. Freshwater)?
- Cells have a higher osmotic pressure than surrounding environment. The water will flow into the cells causing them to burst.
- A hormone is discovered that rapidly accumulates inside renal cells in the absence of endocytosis when administered to mice intravenously The hormone is most likely a?
- Steroid because hormone must diffuse throught he plasma membrane. Steroid hormones are small and hydrophobic and can freely diffuse through the plasm membrane. Polypeptides CANNNOT diffuse throught membranes since they are large hydrophilic molecules. 2nd messengers carry hormone signals inside the cell but are NOT themselves hormones. Neurotransmitters are charged molecules that work at the cell surface.
- Microtubules make up?
- 1)Mitotic spindles
2)Flagella (sperm) and cilia (allows ova to enter the fallopian tubes AND removes bacteria and other particles from the lungs)
3)Organelle movement: Scaffold that organelles interact with to move within the cytoplasm
---ACTIN MICROFILAMENTS make up amoeboid motility of cells
- Importance of endocytosis?
- Endocytosis is the process by whcih the cell internalizes receptor-ligand complexes from the cell surface, such as polypeptide hormones bound to their receptor. At the cell surface, the receptor-ligand complexes cluster in clathrin-coated pots and pinch off the vesicles that join acidic compartments known as endosomes.
- Chain of events that occurs in the synthesis of polypeptide?
- 1)DNA generages mRNA
2)mRNA moves to the ribosomes where a tRNA anticodon binds to an mRNA codon, causing amino acides to join together in their appropriate order.
- The reaction of glucose-6-phosphate to riulose-5-phoshate is a ?
- OXIDATION OF G6P: Its an oxidative decarboxylation, in which glucose's terminal aldehyde is oxidized to a carboxylic acide which is then removed.
- When does recombination occur?
- Recomination ONLY occurs in MEIOSIS!!
Recombination (crossing over): A process in which portions of two genomes are exchanged to make one with a new combination of alleles.
- Role of cytoskeletal protiens in mitosis?
- Microtubules known as polar fibers radiate from the centrioles to connect with kinetochore fibers, also composed of microtubules, emanating from the centromere. Centromere is the organizing center of each chromosome, while the centrioles, at the center of the microtubules organizing center, are the organizing poles of the dividing cell. The polar fibers cause separation of sister chromatids during anaphase. the entire bundle of fibers, including the polar fibers and the 2 asters is called the spindle.
- What is the difference b/w eukaryotic and prokaryotic flagella?
- Eukaryotic flagella are cytoplasmic extrensions with a 9+2 arrangement of microtubules.
Prokaryotic flagella are formed from chains of a protein called flagellin and are attached to the cell surface (as opposed to being cytoplasmic extensions)
- The first sign of mitosis?
- Visible Condensing of the chromosomes at the beginning of mitosis, during prophase.
- Mitosis occurs in which of the following human cell types?
- Bone marrow cells
---NOT in erythrocytes because they are terminally differentiated and lack a nucleus in humans. They are incapable of mitosis and must be continually replenished by stem cells in the marrow.
ALSO, Primary spermatocytes undergo meiosis to form secondary spermatocytes.
- What is crossing over?
- Corssing over occurs between paired homologues before they separate into 2 different nuclei. This is a feature unique to meiosis. As a result of crossing over, the daughter cells have combinations of chromosomes different fromt hose in the parents.
In mitosis the daughter cells are identical to the parent cell.
- Chloroplasts and mitochondira have their own chromosomes. The genomes of chloroplasts and mitochondria must replicate during?
- THE G1 PHASE because Organelles are produced during G1. Replication of corganelle DNA is not coupled to replication of the nuclear genome, so it probably occurs during G1.
The S phase is the time when cellular chromosomal material is replicated.
- The membrane-spanning regions of the ATPase would most likely consist of amino acids with side groups that are?
- HYDROPHOBIC and NONPOLAR because they must interact wit the hydrophobic lipid tails of the membrane interior.
- Simple diffusion vs. Facilitated diffusion vs. Osmosis vs. active transport?
- Diffusion is the flow of molecules down a concentration gradient, but simple diffusion is not a protein-mediated event. WIthout the involvement of a protein as an ion channel, sodium ions cannot diffuse through a bilayer membrane. Facilitated diffusion is the flow of molecules down a concentration gradient with the assistance of a protein such as an ion channel. Osmosis is the flow of water to equalize a difference in solute concentration, not the net movement of solute across a membrane. Active transport is movement against a gradient, not with it, and requires ATP hydrolysis.
- The direct role of tumor initiators is to cause?
- Changes in the DNA sequence of a cell
- What may be seen in cancerous cells?
- 1)Changes in the cell cycle: Cancer cells divide more rapidly and have a differently-proportioned cell cycle from normal cells.
2) Changes in gene expression
3) Ability to respond to hormonal control: Cancer cells may lose their ability to respond to hormonal control, but some cancers retain this ability.
- What can could cause cancer?
- Cancer often results from a change in the gene coading for a receptor. Receptors are protiens which allow hormones to exert control over individual cells. Receptors which do not repond normally to their lignads can result in an out-of-control cell.
1) Mutation in the gene coding for a cell surface receptor
2) A mutation in the gene coding for a steroid receptor.
3) Deletion of the gene coding for a receptor's regulatory subunit
NOT: An error in translation of a cell surface receptor because errors in translation do not have significant effects on cellular function. Only mutations in DNA cause permanent changes in a cell's behavior and are passed down to daughter cells.
- Primary oocytes are found at what stage of meiosis?
- MEIOTIC PROPHASE I: Primary oocytes are arrested for years at meiotic prophase I from birth until ovulation.
- Which of the following is a characteristic of the acrosomal reaction that occurs in sperm of sea urchins during fertilization?
- Acrosome: A huge modified lysosome that is packed with zona-difesting enzymes and located around the anterior part of the sperm's head. Enzymatic drill to get through sona pellucida. Acrosomal reaction is actually accompanied by an increase in Ca2+ and pH.
1) Actin is polymerized to create an acrosomal process in the sperm
2)Hydrolytic enzymes are released that digest the jelly coat.
3)Spedific proteins are exposed that can bind receptors on the egg (known as bindins)
- Which hormones stimulate spermatogenesis in humans?
- 1)LH:acts on Leydig cells
2)FSH: acts on Sertoli cells to promote spermatogenesis
3)Testosterone: Acts on testes, causing them to produce sperm, but spermatogensis could not proceed without LH and FSH.
- When pathogens invade tissues, they trigger an inflammatory response which dilates blood vessels. This leads to?
- An increase in fluids entering the tissues because the dilation of blood vessels in inflamed tissue increases the pressure in capillaries, increases their permeability and increases the flow of fluid out of the plasma into the extracellular space in surrounding tissues.
- What enzymes digests what?
- Pepsin and trypsin hydrolyse proteins.
Lipase hydrolyses triglycerides.
Amylase is responsible for hydrolysis of starches into simpler sugars.
- In the increased biosynthesis of neurotransmitter receptors, activity of the rough endoplasmic reticulum increases because?
- It is the primary site of plasma membrane protein synthesis.
Neurotransmitter receptors are integral plasma membrane proteins, all of which are translated on the rough ER. Increased plasma membrane protein translation requires more rough ER.
- Which excitatory neurotransmitter is responsible for excitatory stimulation of skeletal muscle at the neuromuscular junction?
- The excitatory neurotransmitter at this junction is acetylcholine. ACh binds to a receptor on the post-synaptic cell, opening a Na+ channel and causing depolarization of the cell.
- Prokaryotic organisms lack which subcellular structure?
- How many molecules of ATP would be produced upon complete oxidation of 1 molecule of glucose?
- Glycolysis: 2 ATP and 2 NADH
Pyruvate Dehydrogenase: 2 NADH
Krebs Cycle: 2 GTP, 2 FADH2, 6 NADH
1 NADH = 2.5 ATP
1 FADH2= 1.5 ATP
30 ATP for Eukaryotes (because electrons from glycolytic NADH in cytoplasm must be shuttled to the electron transport chain in the mitochondria)
32 ATP for Prokaryotes (E. Coli)
- Binary Fission?
- bacteria reproduce asexually in a process of simple cell division termed binary fission. The DNA and other contents of a cell are replicated then divided equally between the 2 daughter cells.
- what are Protozoans?
- Unicellular eukaryotes mostly heterotropic and in many cases can reproduce either sexually or asexually.
- When the hormone ACTH activateds the adenylate cyclase cascade in target cells, the expected result is that blood levels of ?
- ALDOSTERONE will INCREASE
because ACTH stimulates adrenal cortex to produce cortisol and aldosterone.
- A prostetic group plays a major role in the identification of an enzyme. What is true about them?
- 1) They are non-protein organic molecules associated with the enzyme.
2) They are added to proteins after translation
3) They are needed in order for some enzymes to catalyze reactions.
Prosthetic groups are not part of the amino acid sequence of proteins, but are nonprotein components of enzymes which are required for enzyme activity. For example, some enzymes contain biotin as a prosthetic group.
- Antibodies specific to the mitotic spindle apparatus would most likely recognize products of?
- TRANSLATION because the spindle is composed of microtubules which are polymers of tubulin protein monomers. Anitobodies against the spindle will recognize proteins, which are produced during translation.
- Yeasts are similar to molds in all of the following characteristics EXCEPT that yesats?
- YEASTS are UNICELLULAR!!
Both Yeasts and Mold are both fungi and are eukaryotic, remain haploid throught most of their lives and are both spore-producing organisms.
- what might cause a mutation?
- A defect in DNA replication because DNA is replicated from DNA so a change in the DNA genome must occur during DNA replication.
- In all fermentation processes the final acceptor of electrons from NADH is?
- FERMENTATION-->FINAL ACCEPTOR IS AN ORGANIC COMPOUND.
WHILE, During oxidative phosphorylation the final electron acceptor from NADH is O2.
- When lactic acid accumulates in muscles it is gradually carried away by the blood to the liver. What effect does lactic acid have on respiratory rate?
- It increases respiratory rate because it decreases the pH of plasm. CO2 dissolved in plasm also decreases the pH through conversion to carbonic acid. The respiratiory rate is regulated to increase when the plasm becomes more acidic getting rid of CO2 and making the plasma more alkaline again.
- Which structure is found in bacterial cells?
- RIBOSOMES. Ribosomes are assemblies of protein and RNA, not organelles, and although there are differences between prokaryotes and eukaryotes, both forms of life have ribosomes.
Bacteria are prokaryotes and therefore lack all subcellular membrane-bound organelles. NO mitochondrion, Endoplasmic reticulum or Nuclear membrane.
- oogonium--1-->Primary oocyte--2--> seconary oocyte--3-->fertilized egg--4-->zygote
- oogonium--1-->Primary oocyte--2--> seconary oocyte--3-->fertilized egg--4-->zygote
During embryonic development of females, oogenesis proceeds up to the formation of primary oocytes, which are are arrested in meiotic prophase I in the ovaries from birth until they are stimulated to ovulate sometime during sexual maturity. They will remain arrested at this stage up until the time that they prepare for ovulation and complete meiosis I (including anaphase I) to form secondary oocytes which are ovulated.
- Klinefelter's syndrome in which a male has an extra X chromosome )XXY) is the result of nondisjuction. The failure in spermatogenesis that could produce this would occur in?
- ANAPHASE I. During meiosis, homologous chromosomes separate during meiosis I, and sister chromatids (identical copies, except for recombination) separate during meiosis II. In Klinefelter's syndrome, for a sperm to cause the defect, it must contain both an X and a Y chromosome. X and Y could count as "homologous chromosomes" and so would normally separate during meiosis I. Failure to do so could create a sperm containing both an S and a Y which could cause Klinefelter's syndrome. The separation occurs during anaphase, when chromosomes are drawn away from each other toward opposite sides of the 2 cells being formed.
- In the frog embryo, which of the following cell groups give rise to the muscles?
- MESODERM: The mesoduerm forms muscles, blood, bone, reproductive organs and kidney.
- Which of the following is derived from embryonic ectoderm?
- CEREBELLUM: The ectoderm forms the skin and the nervous system including the BRAIN.
- During which of the following are cells iwth a single unreplicated copy of the genome formed in humans?
- MEIOSIS II: In humans, the only cells that have a single copy of the genome are gametes, formed during meiosis. Cells have a single unreplicated copy of the genome after the 2nd meiotic division.
- OXIDATION? REDUCTION?
- OXIDATION: Loss of Hydrogen or Increase Bonds to Oxygen
REDUCTION: Decrese bonds to Oxygen or Increase Hydrogen.
- Where does Fatty acid oxidation occur?
- MITOCHONDRIAL MATRIX: same place as TCA cycle and the decarboxylation of pyruvate to acetyl-CoA.
- Where is the site of initiation/translation of protein synthesis in eukaryotic cells?
- CYTOPLASM: All translation is initiated on cytoplasmic ribosomes.
Transcription takes place in the nucleus.
Proteins destined to be secreted into the Rough Endoplasmic Reticulum lumen have a special sequence of amino acids at thei amino terminus. This sequence is recognized by the signal recognition protein (SRP), which binds to a receptor on the rought ER attaching the ribosome and the nascent polypeptide to the ER membrane.
- What is true regarding eukaryotic protein synthesis?
- 1) The mRNA is spliced BEFORE translation.
2) Eukaryotic ribosomes (80S) are larger than prokaryotic ribosomes (70S).
- What is TRUE about prokaryotic translation?
- 1) The N-terminal amino acid of every nascent polypeptide is formylated
2) The mRNA chain being translated may not be fully transcribed at the time of translation. This is because prokaryotic mRNA has no nuclear membrane to cross, its translation can begin even before its synthesis is complete. HOWEVER< eukaryotic mRNA must be spliced and transported across the nuclear membrane before translation can begin
3)The mRNA is not spliced before initiation
4)Hydrogen bonds between mRNA and tRNA codons are essential for translation of the genetic code.
- What is true about plasmids?
- 1) They are transcribed and translated simultaneously. Like bacterial genomes, plasmids are found free in the cytoplasm and they are not membrane-bound.
2) They are replicated by bacterial enzymes. Plasmids rely on bacterial machinery for replication and transcription.
3) Plasmids are extrachromosomal circular DNA molecules, not organelles. Organelles are membrane-bound cellular components present only in eukaryotes.
- How is it possible for fragment of DNA produced by cutting with a restriction enzyme to be ligated into a plasmid in 2 different orientations?
- Both ends of a fragment produced by a restriction enzyme are identical if rotated 180. The sequences recognized by most restriction enzymes are inverted repeats that read the same if flipped 180. The sticky ends of both ends of a fragment are the same if the fragment is rotated in either orientation so it does not matter to the ligase whyich orientation occurs.
- In an operon, what best describes the promoter?
- The promoter is the binding site for RNA polymerase and recognized as the transcription initiation site.
- Competitive Inhibition
- The inhibitor competes with the substrate for enzyme active site, which increases the apparent Km but Vmax stays the same.
- Vmax is dependent on?
- TOTAL ENZYME CONCENTRATION ONLY because Vmax is dependent on total enzyme concentration. Vmax is the reaction velocity at a fized enzyme concentration. Adding more enzyme would allow more catalysis to occur per minute.
NOT on Substrate concentration. V not Vmax depends on [S]. Vmax is a constant for each enzyme as long as the amount of the enzyme is constant.
NOT on the concentration of inhibitor that reversibly binds to the enzyme's active site. If the inhibitor binds to the active site reversibly, then we are talking about competitive inhibition. Adding enough substarte will overcome this inhibition, and the original Vmax will be reached.
- What would happen if the enzyme concenration were not kept constant during measurement of reaction velocity as a function of substration concentration.
- Vmax would change but km would remain constant. Vmax will be proportional to the # of active sites (enzyme molecules), but Km will not change. Km is a measure of active-site affinity for substrate. No matter how many enzyme molecules are present, each enzyme interacts iwth substrate in the same manner.
- Which one of the following does NOT take place in the mitochondrion?
- GLYCOLYSIS!!! Glcolysis takes place in the Cytoplasm.
Krebs cycle, Electron transport and Oxidation of pyruvic acid all takes place in the mitochondrion.
- What is an Auxotroph?
- Autotrophs: Auxotrophs have a mutation preventing them from growing on minimal media
- After conjucation between an F+ cell and an F- cell, the resulting genotypes of the F+ and the F- cells respectively become?
- F+, F+: Because the F factor is replicated, the donor remains F+. The recipient cell becomes F+ after conjugation because it receives the F plasmid from the donor.
- After the completion of gastrulation, the embryo undergoes?
- Neurulation and organogenesis follow gastrulation. Gastrulation is when the 3 primary germ layers become distinct.
Blastula formation comes fefore gastrulation
Lens of Eye (Retina)
Epidermis (Outermost layer of the Skin)
Lining of Body Cavity
Dermis (2nd layer of skin under the epidermis.)
(AND most of the other stuff between the gut and the skin)
Inner lining of the gut
Lining of digestive tract
Lining of respiratory
- What is true about differentiated cells?
- Only a subset of all the genes inherited from the zygote are expressed to give the cell its characteristics. Differential expression of genes is what gives cells their different characteristics.
The genome remains intact during development with no loss or gain of genes (B and T cells of the immune system are an exception)
Determination is what destines a cell to differentiate into whatever specific type it is going to be.
- -Totipotent cells have the potential to develop into any part of the animal (developing zygote).
-It is not observed in ectodermal cells because if cells are ectodermal, then they have already narrowed down their developmental options and are unlikely to form endodermal or mesodermal tissues.
-It is usually lost by the end of gastrulation. Cells have lost their totipotency and are fated to develip into certain cells.
- Increased levels of Thyroid hormome would result in which of the following physiological effects in humans?
- Thyroid hormone increases the rate of overall metabolism in many different ways
1) Increased cardiac output and heart rate
2) Increase rate of glycolysis, krebs cycle and oxidative phosphorylation
3) Increased oxygen consumption
4) Increased need for vitamins and nutrients. The increased metabolic rate also increases the need for certain enzymes involved in producing energy and the cofactors these enzymes use. many cofactors are derived from vitamins, leading to an increased need for certain vitamins.
- Would a patient who had sufferent loss of the anterior pituitary due to surgery be likely to show reduced levels of secretion by the thyroid?
- YES becasue tyroid hormomes secretion is normally regulated by anterior pituitary secretion which produces TSH which stimulates thyroxine production.
- High levels of Corticotropin releasing factor (CRF) and Adrenocorticotropic hormone (ACTH) would be found in an animal:
- CRF(from hypotalamus) and ACTH( from anterior pituitary gland) secretion are associate with stress
1) Receiveing an electric shock
2) With a wound
3) With adrenal glands removed. There would be no cortisol present and in the absence of feedback inhibition, CRF and ACTH levels would be very high.
4) NOT with a cortisol secreting tumor. High levels of cortisol would be present in the blood and would repress DCF and ACTH secretion by feedback inhibition.
- Cortisol is bound to receptor protiens in the cytoplasm of target cells. This binding is necessary for?
- The action of cortisol and its receptor in teh nucleus. Cortisol is a sertoid hormone. Hormones of thsi class act by hinding to intracelllular receptors which regulate gene transcription in the nucleus.
- hjow do you explain the fact that during administration of 1 electric shock, cortisol secretion increases and then stabilizes until the stimulus is withdrawn?
- Electroshock stimulates secreation by the hypothalamus. If shock causes the hypothalamus to increase CRF secretion, then cortisol secretion (from the adrenal cortex) will increase and then decrease again once shock is removed.
Cortisol causes and increase in plasma glucosem making extra energy resources available under stressful condition. it also incrases the rate of protein catabolism, making additional amino acids available for tissue repair. It also decreases sensitivity to histamine thus diminishing pain percetption and inhibits the tissue inflammatory response, preventing swelling at sites of injury.
- In studying viral synthesis of the H antigen(protein composed of amino acid residues), what findings would a researcher most likely discover?
- tRNA must bind to the ribosome before translation can occur. True for any translated protein. mRNA for viral or cellular protiens will be translated in the same way since the virus must utilize cellular machinery for translation.
- What can be associated with striated muscle contraction?
- Cardiac and skeletal muscles are striated. Smooth musle is not.
Therefore Simple reflex arc of the knee is Skeletal muscle and motion of the fingers are skeletal muscle and pumping of the heart is cardiac muscle so they are all striated.
Peristalsis of the digestive tract is smooth muscle and therefore not striated.
- Muscle cell continued to contract when Ca2+ remained in teh cell because Ca2+ causes?
- Release of actin-myosin inhibition by troponin and tropomyosin. Calcium links excitation with contraction. The action potential causes Ca2+ release from the SR. This Ca then causes troponin and tropomyosin to releae actin, revealing myosin binding sites so that myosin can bind to actin and catalyze sliding of filaments past each other. As long as Ca remians present, myosin will bind actin and the muscle will remain contracted.
- During skeletal muscle contraction, which bands can be seen to contract under the microscope?
- THE I and H BANDS.
-H bands: Myosin thick filaments only
-I bands: Actin thin filaments only
-A bands: Myosin filaments
-Z lines: Ends of sarcomeres
- What is True about cardiac muscle?
- 1) It is striated. Essentially the same organization of actin/myosin myofilaments found in skeletal myuscle that give this tissue a striated appearance.
2) It acts as a functional syncytium since neighboring cells are linked by gap junctions that communicate action potentials directly from cytoplasm of one cell to another. Not a true syncytium becuase it does not have more than one nucleus per cell.
3) It is under control of the autonomic nervous system.
- What hormones are released by teh anterior pituitary gland?
NOT ADH: THAT is Posterior Pituitary (Pee Pee)
- How does your body retain water/prevent water loss?
- Increase these Hormones:
- During the production of urine, the nephron controls the composition of urine by all of the following physiological processes:
- 1) Secretion of solutes into Urine
2) Reabsorption of water
3) Countercurrent exchange with Blood
4) NOT: filtration to leave Na+ in blood because ONLY large solutes like proteins are filtered out. Sodium ions pass freely into the filtrate and must be reabsorbed later in filtrate processing to make urine.
- In the condition myopia (near sighted) the inverted image formed by the lens falls?
- In front of the retina generally due to the shape of the eye being too long.
- Females with Turner's syndrome have a high incidence of hemophilia, a recessive X-linked trait. Based on this statement, it can be inferred that females ith this syndrome have?
- LOST AN X: A recessive trait will only be expressed if it is present in both copies or is the only copy of the gene present. A recessive X-linked allele will only be expressed in normal women who have 2 copies of the allele. If only one X is present, however, then all recessive alleles on the X will be expressed such as heophilia.
- The cell bodies of a somatic sensory nerve are located in the?
- Dorsal root ganglion.
Cell bodies of somatic sensory neyrons are not located in the CNS. They are located in dorsal root ganglia just behind the spinal cord all along the length of the spinal cord.
- Nerve cells that control thermoregulation are concentrated in which portion of the brian?
- HYPOTHALAMUS!! The hypothalamus is a key regulator in many different processes such as food intake,blood pressure, and neyroendocrine control as well as temperature regulation.
-Medulla: Blood pressure, repiratory rate, vomiting
- Hair cells used to detect motion are found in which structures?
- 1)The ORGAN OF CORTI
2)The SEMICIRCULAR CANALS
Both the organ of Corti and the semicircular canals contain hair cells with small "hairs" that project from the apical surface of the cell into the surrounding fluid. Movement of the fluid around the hair cells detects sound in the organ of Corti and a change in body orientation in the semicircular canals.
- At which portion of the nephron does aldosterone exert its effect?
- The DISTAL CONVOLUTED TUBULE: Aldosterone increases sodium uptake and water reabsorption along with it, in the distal convoluted tubule and the Collecting duct.
- Connective tissue functions to hind and support other tissues. Which of the following are examples of connective tissue?
- Cartilage and bone: Acts to connect ad support and are related in their lineage and activities.
-NOT Connective Tissue: Muscles is a distinct tissue in form function and Derivation.
- What are the characteristics of polypeptide hormone activity?
- 1)Transmission is via blood cirulation
2) Cellular effects often require protein kinase activity
3) Targent organ is distant from site of release
4) NOT TRUE: Hormones pass through the target cell membrane and enter the nucleus. Because Polypeptide hormones are large and hydrophilic and therefore cannnot pass thorugh a cell membrane.
- What substances are involved in bone remodeling?
- 1)Vitamin D
2) Parathyroid Hormone
These three are involved in Calcium metabolism and bone remodeling.
4) NOT Thyroxine. Thyroxine has important general metabolic effects but is not involved in bone remodeling.
- What prevents pepsin from destroying the cells of the stomach that produce this hydrolytic enzyme?
- Pepsin remains in an inactive state until it is cleaved by HCL. Pepsin and many other proteases are secreated in a "zymogen" form which is inactive when first translated and secreted and must be activated in the proper extracellular environment. Pepsin is scereased in the inactive pepsinogen, which is cleaved in the acidic condition of the stomach to form the active protease pepsin.
- The liver has what functions?
- 1) Storage of carbohydrates as Glycogen during preiods in which carbohydrates and energy are abundant
2) Conversion of carbohydrates to fats. Fat metabolism. If glycogen stores are at maximum levels, glucose is converted to fatty acids and stored as triglycerides.
3) Deamination of amino acids can be performed inthe liver to allow amino acids to enter metabolic pathways, providing energy.
4) NOT sysnthesis of red blood cells. This occurs in the bone marrow and is not associated with the liver.
- What blood component is responsible for coagulation?
- PLATELETS: Platelets are small pieces of large cells called megakaryocytes. When a wound occurs platelets can be activated to stick to the edge of the wound site and release their contents, stimulating the clotting reaction.
- Which organ is involved in the absorption of all of the following: amino acids, mono-and disaccharides and fatty acids?
- SMALL INTESTINES: The small intestines is specialized for absorption of a variety of nutrients with a large surface area due to the villi and microvilli facing the lumen.
- Compared to the human kidney, the kangaroo rat kidney is capable of producing more concentrated urine because it permits?
- A GREATER OSMOLAR GRADIENT FROM CORTEX TO MEDULLA: It is the high osmolarity of the medulla that plays a key role in the formation of hyperosmotic urine. The greater the osmolarity of the medulla, the more concentrated the urine can be.
- What describes the relationshop between hydrostatic and osmotic pressure differentials in the capilliaries.
- THE HYDROSTATIC PRESSURE DIFFERENTIAL CAUSES FLUID TO MOVE OUT OF TEH CAPILLARIES AT THE ARTERIAL END: Arterial pressure is higher than the pressure on the venous side of the capillaries. Thus, hydrostatic pressure tends to drive fluids out of the blood and into the tissues on the arterial side and back out of the tissues on the venous side. Osmotic pressure is greater in the plasma than in the interstitial fluid because plasma has a much higher protein concentration; therefore, osmotic pressure tends to draw fluid into the blood, out of the tissues.
- After T cell activation, the intracellular Ca2+ concentration must be restored to its very low resting level. In the absence of ATP, how can Ca2+ levels be restored?
- Ca2+ IS ACTIVELY TRANSPORTED ACROSS THE INNER MITOCHONDRIAL MEMBRANE.
Note: In most eukaryotic cells, only mitochondria create a non-ATP-dependent electrochemical gradient (a proton gradient dependent upon electron transport). The mitochondirial proton gradient which is normally used for ATP synthesis can be used to actively transport Ca2+ into mitochondia when the intracellular Ca2+ concentration reaches abnormally high levels, which occurs in the absence of ATP. This is an example of active transport not directly or indirectly dependent on ATP hydrolysis.
- What prevents unspliced mRNA coding for MHC Class I proteins from being translated in the nucleus?
- Ribosomes are excluded from the interior of the nucleus. Ribosomes are made and partially assembled in the nucleolus within the nucleus. Assembly is completed in the cytoplasm and the large ribosomal assemblies are then excluded from the nucleus.
- What cell makes antibodies against viruses?
- B CELLS!
Activated B cells known as plasma cells are the only cells that make antibodies.
- Which of the following properties is shcared by both smooth and skeletal muscle?
- ACTIN-MYOSIN CROSS BRIDGING CAUSES CONTRACTION. Both smooth and skeletal muscle generate force by this mechanism.
FALSE: Microsopic banded appearance-only skeletal and cardiac muscles have this banding (striations). Striation is due to the presence of ordered arrangements of actin and myosin known as sarcomeres. Smooth muscles lacks sarcomeres, and thus lacks striateions. This is why it is called "smooth". Instead, its actin and myosin filaments are scattered throughout the mytoplasm in a poorly organized maller.
-Smooth muscle is controlled by the parasympathetic nervous system, a portion of the autonomic nervous system, and is thus not under voluntary control. Skeletal muscle, is controlled by somatic motor nerves, which are voluntary.
FALSE: Can be excited or inhibited by nerve stimulation- This is only true of smooth and cardiac musle, but not of skeletal muscle, where the only effect of nerve stimulation is exciteation.
- The first step in the contraction of smooth muscle is?
- AN INCREASE IN CYTOSOLIC CALCIUM.
An increase in cytosolic Ca2+ concentration is the initiator of all muscle contraction. In smooth muscle, it activates myosin light chain kinase.
- Blocking of Na+ channels might affect what?
- 1) Postganglionic parasympathetic axons
2) Skeletal muscle
Sodium "fast-channels" are responsible for propagating the action potential in nerves and skeletal muscles. the onpening of the fast channels causes the classic spike potential. Na+ fast channels are also important in cardiac muscle, but here Ca2+ "slow channels" also play an important role. In smooth muscle, only the Ca2+ slow channels are impoartant (few if any Na+ fast channels are present)
3) Axon Hillocks: This is where action potentials normally starts
4) NOT binding of ACh to its recuptor: The binding of neurotransitters to their receptors is a specific high-affinity reaction which has nothing to do with wahtever events may ensue thereafter. AP causes neyortransmitter realse and AP resulting from neurotransmitters binding to receptors would be inhibited by TTX but the actual binding of ACh to its receptor would be unaffected.
- Systolic blood pressure approaches 0 mmHg when it reaches the?
- RIGHT ATRIUM:Blood from the systemic circulation enters the heart through the right atrium, and at this point its pressure is near 0 mmHg.
NOT Capillaries:Althought blood pressure is relatively low in the capillaries, it is not that low, or it would never circulate all the way back to the heart.
NOT Arteries: blood pressure in the arteries is high, as it has just left the heart, and has to travel thorugh most of the circulatory system before returning.
NOT Aorta: Blood leaves the aorta on its way to the systemic circulation, and is thus at its highest pressure.
- Circulatory System/Flow of blood?
- 1) Right Atrium (low pressure)
2) Right Ventricle
3) Lungs via pulmonary artery
4)Pulmonary capillaries/alveoli/RBC pick up Oxygen
6)Left atrium (high pressure)
8)Aorta to body cirulation
9)Coronary afteries: Arteries that carry blood to head is located at aortic arch. Decending aorta carries blood down center of the body.
13)Veins: Superior vena cava carries blood from upper body to heart. Inferior Vena Cava carries blood from lower body to heart.
- Cardiac output is influenced by which of the following?
- 1) Nervous input: Parasympathetic nerves to the SA node keep the heart rate slow when one is resting and sympathetic stimulation increases the heart rate.
2) Hormones: Circulating hormones affect cardiac performance. The key example is epinephrine from the adrenal gland, which increases cardiac output.
3) Blood Pressure: Increased blood pressure makes it mre difficult for the heart to eject its load of blood, and decrease blood pressure impairs cardiac function when not enough blood is returned to the pumping heart.
- What are the functions of the lymphatic system?
- 1) Returning white blood cells to the circulatory system: White blood cells escape blood vessels(using amoeboid motility), conduct their business in the tissues, and can return to the blood circulation by lymphatic flow, stopping at lymph nodes en route.
2) Maintaining protein concentration in the blood: The lymphatic system does maintain protein concentrations in the blood by returning leaked proteins from the interstitium to the blood circulation.
3) Transporting fats from the digestive tract to the circulatory system in the form of chylomicrons.
**The lymphatic system has NO role in the circulation of red blood cells. THye do not escape blood vessels, becasue they are large and lack the amoeboid motility of white blood cells.
- Lymph flow is facilitated by?
- 1) Contraction of skeletal muscles
2)Contraction of lymphatic smooth musles
3) Negative pressure created by valves
- What is the primary function of lymph nodes?
- DETECTION OF FOREIGN SUBSTANCES FROM THE BLOOD STREAM: The lymph nodes are the place where antigen sampling and the early stages of the immune response occur. It returns intact proteins to the bloodstream. It also transports fats from the intestine to the bloodstream in the form of chylomicrons.
- Platelets do not normally aggregate in the absence of tissue injury because?
- THEY ARE NOT EXPOSED TO COMPOUNDS PRESENT IN DAMAGED CELLS: Platelets bind to exposed collagen in damaged tissue to trigger clotting.
-Platelets are always present in plasm. T cells play a role in mmmunity not in hemostasis.
- Antibiotics are generally used for bacterial infctions. They are such valuable drugs becasue they are imminetly fatal to bacteria but generally harmless to us. this results from the great differences between the prokaryotic cell and the eukaryotic cell. The challenge in treating cancer and viral and eukaryotic infections is to kill the abnormal cell type without killing healthy cells.
- How would the mutation causing sickle-cell anemia affect the characteristics of hemoglobin?
- 1) It would change the primary structure: Primary sturcutre refers to the sequence of a.a. comprising a polypeptide.
2) it would cause abnormal interaction between hemoglobin molecules: The abnormal valine residue is hydrophobic and replaces a hydrophilic reside (glutamate) on the surface of the folded polypeptide. Hydrophobic interactiions between the abnormal residues on the protein's surface lead to the formation of gigantic macropolymers (many Hb molecules stuck together) which becom so large that they distort red blood cells.
3) It would change the isoelectric point: This change also affects the charge of the protein and would thus change the isoelectric point.
- If the Plasmoidial merozoite were viewed as an independt organism, its life cycle would most resemble that of a?
- LYTIC VIRUS: Infect the host cell and soon lyse it and release many progeny viruses which go on to infet other cells.
Lysogenic viruses infect the host cell an dthen either enter a dormant phase in which the viral genome is integrated inot the host genome.
A saprophyte is an organism which derives its nourishment from dead organisms. The host cell of the merozoite is the living r.b.c. A predator is an organism which eats living organisms smaller than itself.
- Gall stones are crystallized bile acids which may block the bile duct. What do they cause?
- DEFICIENCY OF FAT-SOLUBLE VITAMINS: Micelles formed from bile acids are essential for the absorption of fats and fat-soluble vitamins.
- Muscle cell contractions during peristalsis (which is made up of smooth muscle) are initiated by the?
- FLOW OF Ca2+ IONS INTO THE CYTOSOL: Contraction of all muscle types is initiated by an increase in cytoplasmic calcium. Contraction of muscle cells in caused by an increase in cytoplasmic calcium. The concentration of Ca2+ in the extracelular fluid can modulate the force of contraction of smooth and cardiac muscle, but it is the intracellular Ca2+ which actually initiates contraction. No such variablility exists iwth regard to the skeletal muscle cell. Increased force of contraction of voluntarty muscle groups is accomplished by moto unit recruitment.
NOTE: Smooth muscles does not contain troponin (and therefore not Troponin-tropomyosin complex), T tubules, or sarcomeres.
- ATP is a convenient carrier of energy because?
- IT HAS PHOSPHATE GROUPS WITH AN INTERMEDIATE TRANSFER POTENTIAL: What makes ATP a particularly good energy carrier is that it has an intermediate transfer potential. This allows highter energy phosphate carriers like creatine phosphate to drive the synthesis of ATP from ADP + Pi by transferring their phosphate group to ADP.
- At extremely high altitudes, the low PO2 causes an increase in the rate of breathing. What results from the increased ventilation?
- 1) An abnormally low PC02: Increased ventilation results in an increase in the amt of C)2 expired.
2) Respiratory Alkalosis: Since less CO2 is present to turn into bicarbonate plus protons
3) A very small increase in the amt of O2 transported: Since O2 is insoluble in H2O it must be carried by hemoglobin. Hb is very efficient scavenger of O2 in the lungs. It becomes saturated with O2 easily. Changes in the respiratory rate doesn't tend to change the amt of O2 carried in the blood much. Because CO2 is H2O soluble much of it is carried free in the blood. Thus, am increase in ventilation, which lowers PCO2 in the alveoli, will lead to much more CO2 leaving the blood. So changes in respriation do affect the plasm CO2 level, even though they do not affect the O2 level.
OVERALL: INCREASE O2 (hyperventalation) causes Decrease CO2 and therefore Increase in pH (Basic)
DECREASE in O2 (Hypoventilation) causes Increase CO2 in blood which causes Acidosis which is decrease pH. Because HCO3- + H+.
4) NOT acidic urine: When plasm pH is too high, the kidney will create alkaline urine to compensate.
- Migratory animals that move annually to warmer climates must dissipate metabolic heat. This is often accomplished by?
- DILATING BLOOD VESSELS TO THE SKIN: A mechanism used to get rid of excess heat is to dilate arterioles leading to the skin putting more blood closer to the atmosphere where teh heat can radiate away.
- Some mammels have unusually long loops of Henle that maintain steep osmotic gradients. This allows for the organism to:
- EXCRETE URINE THAT IS MORE HYPERTONIC: The steepter the osmotic gradient in the kidney, the greater the osmolarity of urine that can be achieved to conserve water.
- A small subpopulation of beetles with a slightly advantageous modification of pincer structure was found to be wiped out after a locally-isolated severe wind storm. A biologist studying this event woul most likely attribute the loos of the advantageous g
- GENETIC DRIFT: The random change over time in the allele frequency within a population, such as that caused by the storm in the loss of the allele for the altered pincer stufcture.
FYI: Hardy-Weinberg describes ideal circumstances in which allele frequencies in population do not change.
- Hardy-Weinberg Principle
- The Hardy-Weinberg Principle is an important part of population genetics. It states the conditions that
must be present so that evolution will not occur in a population. It also predicts, on the basis of allele
frequencies, the ratio of genotypes and phenotypes that should be present in the population IF THERE IS
If all of the following conditions hold:
1. mutations do not occur
2. selection does not occur
3. there is no emigration or immigration of individuals into the population
4. mating is random
5. the population is large
- Erythroblastosis fetalis is a condition in which fetal blood cell anigens elicit an immune system response from the mother, causeing clumping of the fetal blood cells. This antigenic factor is called the Rh Factor, and is inherited through a dominant all
- THE FETUS IS Rh+ AND THE MOTHER IS Rh-. The mother must lack Rh antigen herself or else her immune system would recognize this as self and fail to respond. The fetus must express the antigen for the immune response of mother against fetus to develop.
- What is the role of myelin sheath in AP transmission?
- Schwann cells insulate the axons of neurons, causeing membrane depolarization to jump from node to node. The myelin sheath insulateds the neuronal axon except for small gaps (nodes of Ranvier) through which ions can traverse the membrane, causing the AP to leap from node to node. The myelin sheath is not produced by the neuron it is associated with. It is procuced by a different type of cell the Schwann cell that wraps around th axon to creaste layers of insulating myelin.
- Missense mutations: change a base pair, altering one amino acid in a protein.
Nonsense mutation: results in a premature stop codon and a shorter protein.
Silent mutation: one which has no effect on the protein product.
Frameshift mutation: one base pair is inserted, then the triplet codons after that point will be out of phase and read in a different frame than normal.
- The sucess of gene therapy that uses retrovirus vectors (RNA) depends on the existence of an appropriate receptor for the virus on the target cell. This receptor most likely consists of?
- PROTEINS: All viruses gain entry into the cell through recognition of cell-surface proteins (receptors by viral proteins)
Retrovirus is RNA virus capable of transcribing its gennome into complementary DNA within the cell it infects. The enzyme that catalyzes the manufacture of DNA from an RNA template is reverse transcriptase.
- The cells that produce autoantibodies originate from stem cells in the?
- BONE MARROW! All immune cells, both B and T cells originate from stem cells which reside in teh bone marrow.
- Aldosterone secretion is influenced by?
- 1) Plasma potassium concentration
2) Plasma ACTH
3) Renin-angiotensin system
These are all key players in the regulation of water balance and salt resorption and all influence aldosterone secretion either directly or indirectly.
4) NOT serum glucose concentration
- Following adrenalectomy (removal of the adrenal gland) would there be a rapid rise in ACTH in the blood?
- YES, because of the absence of feedback inhibition.
The adrenal glands make cortisol in response to ACTH from the pituitary. In normal regulation, this cortisol represses ACTH (feedback inhibition). In the absence of the adrenal gland, cortisol levels will fall rapidly, and ACTH will increase due to the lack of feedback inhibition by cortisol in the plasma.
- Increases in response to increased plasma calcium. Calcitonin is a hormone secreated by the thyroid gland which acts to decrease plasm calcium and whose secretion is increased by elevated plasma calcium.
- Would an individual without a parathyroid gland be expected to have difficulty breathing?
- YES, because decreased calcium induced convulsions and tetany. In the absence of parathyroid hormone, plasma calcium drops and hypocalcemia results. The hypocalcemia in a person with complete absence of PTH would probably be severe, resulting in convulsions and tetany. Respiration requires properly-functioning nervous stimulation and muscle funcion, and would be impaired by convulsions.
- Noradrenergic/cholinergic fibers
- Stimulation of noradrenergic fibers causes the release of norepinephrine and epinephrine, which inhibit smooth muscle contractions. Stimulation of cholinergic fibers causes the release of acetylcholine, which stimulates smooth muscle contractions.
- In stimulating peristaltic activity, acetylcholine is an organic molecule that has the effect of causing?
- AN INCREASE IN ACTIN-MYOSIN CONTRACTIONS DUE TO INCREASED INTRACELLULAR Ca2+ CONCENTRATION.
- A toxin produced by bacteria that is specific for intestinal cells and causes the vomiting and diarrhea associated with food poisoning.
- How would you compare the effector mechanisms of protein and steroid hormones?
- UNLIKE PROTEIN HORMONES, STERIOD HORMONES DIRECTLY ACTIVATE A RECEPTOR WHICH MODIFIES TRANSCRIPTION AND THUS NEED NO SECOND MESSENGERS. Steroid hormones are very hydrophobic. They change cellular activity by diffusing into the cell where they bind with specific receptor proteins which directly modify transcroption of the genome. Hence, although a receptor is essential, there is no second messenger because the hormone-receptor complex has its effect directly. Protein hormones are too hydorphilic and generally too big to cross lipid bilayers. hence they have their effects by activating cell surface receptors, which activate second messengers, which in turn go on to modify cellular activities. Note that not only is the effector mechanism different between the 2 classes of hormones, but the effect itself is different; steroids affect transcription in the nucleus while protein hormones affect cytoplasmic processes. As a result steroids act much more slowly and their effects are longer lasting.
- Carrying capacity of a population
- Carrying capacity is defined as the # at which a population stabilizes after several years. It is the # of organisms the environment can support in the long term, or "carry". Best when you determine the # of individuals that are present over several seasons.
- Symbiotic Relationships
- 1) Parasitism: A symbiotic relationship in which 1 species is harmed while the ohter benefits. A parasite is an organism which derives its nourishment from the body fluids of its host.
2)Predator-prey relationships: Parasitism is contrasted with predator-prey relationships in that parasites are smaller than their hosts, and are usually species specific.
3)Commensalism: one species benefits while the other is neither helped nor hurt
4) MutualismL both species benefitting for the interaction
5) Predation: Predator usually feeds upon prey smaller than itself and on many different species of prey
- Coevolution occurs when the characteristics of one species influence the evolution of another species. Does not imply "progress" it just refers to change in a lineage over time.
- Speciation is the origin of a new species.
- Reproductive isolation
- Reproductive isolation is one way species diverge to create new species. Relieves intra-speicies competition by creating new species.
- Antibodies act against foreign particles in which of the following ways
- 1) They may coat a foreign particle so that it is taken up by phagocytic cells: Antibodies serve as markers, causing phagocytic cells to engulf and destroy foreign particles or cells.
2) They may bind to a foreign particle, interfering with its function. For example, an antibody can inactivate a virus.
3) They may elicit a cascade leading to the lysis of foreign cells: The complement system is a biochemical cascade which leads to the lysis of cells. It can be initiated by an antibody binding to the cell surface.
- Codominance is the phenomenon in which the effects of both alleles at a particular locus are apparent in the phenotype of the heterozygote. For example, the 2 alleles IA and IB, and both will be expressed in the phenotype which will be blood type AB.
- Epistasis refers to the situation where one gene controls the expression of another. Epistatic is a relationship between genes (loci).
- True-breeding means that the phenotype does nmot change from generation to generation.
- Genetic map
- WE can calculate the genetic map distance between the 2 loci. The map distance between the 2 genes is defined as the frequency of crossover events between those genes. This is simply the number of recobinant offspring divided by the total # of offspring. For example 68/200-34% therefore 34 centimorgans.
- 1)Associative learning: pairing of stimuli.
2)Stimulus driven neuronal development:develipment of neural pathways that were not present at birth. Activity of the sensory nerve drives synapse formation along the pathway.
3) Habituation: Reduced response by existing neurons.
4) Sensitization:leads to an increased response and involves numbers of receptors.
- Synaptic transmission b/w 2 neurons requires several important events. What is common to such synaptic processes, regardless of the neurotransmitter released?
- SYNAPTIC VESICLES FUSE WITH THE PRESYNAPTIC MEMBRANE TO RELEASE NEUROTRANSMITTER.
The receptor on the post synaptic membrane does not generally degrade the neurotransmitter. This is usually done by enzymes in the synptic cleft or bloodstream. Some neurotransmitters (norepinephrine) are not degraded but rather reclaimed by the presynaptic terminal from which they were released.
Action potentials begin at the axon hillock, not at the dendritic spine wehre teh neurotransmitter has its effect. Also, not all neurotransmitters are excitatory, and even if they are they do not directly cause AP, but membrane depolarization.
- Serontonin may?
- ALTER THE STRENGTH OF RESPONSE TO OTHER NEUROTRANSMITTERS.
Serontonin alters the amount of neurotransmitter release by the presynaptic cell, amplifying the response.
- Rods are responsible for dark vision.
Cones are responsible for visual acuity and color vision, not night vision.
- In an experiment, all K+ channels are blocked in a giant squid axon. If the ratio of [Na+]outside to [Na+]inside is 10, then what will be the RMP?
- IT IS DETERMINED SOLELY BY THE ELECTROGENICITY OF THE Na+/K+ ATPase. The Nernst equation is only applicable when the membrane is permeable to the ion in question. It can't be used here, since the membrane is impermeable to sodium, and there are no resting channels for this ion. Normally the nerve cell membrane is permeable to potassium due to specialized channels, and it is K+ effluz through these channels which creates the RMP. If they are blocked, the only significant souce of the transmembrane potential would be the electrogenicity of the ATPas. This refers to the fact that the pump exports 3 na+ for every 2K+ it imports; this results in a negative charge inside the cell relative to outside (same polarity as the RMP). Remember though that this is not the major souce of the RMP-K+ efflux through channels is.
- What effect might the opening of K+ channels twd the end of the AP have on the axonal membrane?
- IT COULD MAKE IT MORE DIFFICULT (BUT STILL POSSIBLE) TO ELICIT ANOTHER AP IMMEDIATELY AFTER THE FIRST ONE: The many open K+ channels at the end of the AP have 2 effects relevant to future APs. 1st they cause transient hyperpolarization (more neg membrane potential). This means taht a greater Na+ influx will be necessary to reach threshold. 2nd, they increase the K+ conductance (permeability), so that any Na+ influx which occurs is more easily counterbalanced than in the resting state. this means that a greater depolarization will be necessary to cause an AP; that is, the treashold is raised (made less neg). The overall result is known as the relative refractory period, in which the membrane can have an AP, but only in response to a much greater depoilarization than normal. In contrast, the absolute refractory period is during an AP, when a new AP cannot be elicited, no matter how large the stimulus. The ARP occurs for the simple reason that all the membrane's fast na+ channels are already ovpen during the spike, and also because when the fast channels close at the end of the spike they become stuck shut for a short time.
- In hearing, the sound wave is transduced into a traveling fluid wave in the?
- INNER EAR! The inner ear is the site where the sound wave becomes a traveling wave.
Sound merely travels through air in the outer ear. The middle ear is comprised of the ossicles. The hair cells transduce the impulse in the traveling wave into a newvous impulse.
- Assuming the choclea to be 100 units long , at what distance from the audiotry ossicles would the basilar membrane most strongly respond to sound of frequency 20 hz the LOWEST frequency that the human ear can detect?
- 100 UNITS: Low frequencies cause the most vibration at the apical end, farthest from the ear drum.
- In sensorineural deafness, hearing loss is restricted to a particular frequency range. which of the following could account for this type of deafness?
- DAMAGE TO A GROUP OF HAIR CELLS: Since hair cells in different locations along the basilar membrane record sound of different frequencies, damage to a portion of hair cells would cause only hearing loss from a portion of the sound frequencies.
- What is the order of the process of translating a sound wave to a nerve impulse?
- 1) Movement of auditory ossicles which are in the middle ear
2)Pressure changes produced within the inner ear: caused by ossicle movement.
3)Displacement of basilar membrane caused by pressure changes of the inner ear.
4)Movement of hair cells that are attached to the basilar membrane with respect to the tectorial membrane
- Nerve impulses from hair cells traveling to the brain get processed finally in the:
- CEREBRAL GRAY MATTER: The cerebral cortex is composed of nerve cell bodies, and appears gray, the cerebral cortex processes "higher" info such as speech, sound, sight, learning, etc. and is the seat of consciousness. Also, hearing nerves of the spiral ganglion send their axons toward the auditory cortex.
A) The cerebellum is the site of coordination of movement and balance.
B)The hypothalamus is the site of the regulation of bomeostasis
C)The cerebral white matter is composed of myelinated axons (it is the lipid-rich myelin which makes it white). it is not considered a processing center but rather an area of complex intertwining pathways leading from 1 processing center to another.
- Highly-tonic receptor cells are usually found in groups, with hearby tonic receptor cells having different, but slightly overlapping, sensitivity ranges. Regarding this arrangement, then tonic cells:
- RESPOND EFFICIENTLY OVER RELATIVELY NARROW RANGE OF STIMULUS INTENSITY. Each tonic receptor cell in such a series measures with great precision but has a restricted intensity range over which it is sensitive since it cannot adapt to strong stimuli. A series of receptor cells with different but overlapping ranges can measure over a large range with great accuracy. This can be inferred from the question, which states that the receptors "have different, but slightly overlapping, sensitivity ranges."
- Cutaneous receptors
- cutaneous receptors are located at specific points in the skin and are relatively sparsely distributed on the skin of the back. this is why it is possible to feel only 1 needle touch when there are actually 2; both needles poke within the domain of a single receptor.
- What is a likely effect of insulin?
- To modify the activity of cytoplasmic proteins necessary for the uptake and utilization of glucose: Insulin is a peptide hormone which binds to a cell-surface receptor, leading to changes in the activity of cytoplasmic proteins. For example, the enzyme responsible for glycogen synthesis is activated, and the enzyme responsible for glycogen degradation is inhibited.
Insulin is normally released when blood sugar is elevated. It functions to lower blood sugar by promoting glucose uptake an dstorage. it promotes glycogen synthesis and inhibits glycogen breakdown. Insulin is necessary for the uptake of glucose into cells.
- The polyuria (abnormally large amount of urine) in diabetes mellitus is caused most directly by which of the disease's other manifestations?
- GLUCOSURIA (glucose in the urine): The excess blood glucose overwhelms the proximal tubules's ability to resorb glucose from the urine. The resulting high urinary glucose concentration (glucosuria) draws excess water into the renal tubules by osmosis.
NOT: Periperal neuropathy: This referst o probelms with peripheral nerves. It can cause incontinence which is the loss of control of the time and place of urination.
NOT: Polyphagia (increased eating) of diabetics which results from the loss of so much glucose in the urine, and the intracellular glucose deficit resulting from absence of insulin's effect.
NOT Hyperflycemia: which cauess glucose to be lost in urine. The glucose loss in urine in turn causes polyuria.
- The initial cause of diabetes could be an autoimmune disorder involving antibodies to:
- 1) B cells of the islet of Langerhans. B cells in the pancrease produce insulin. Destruction of these would cause diabetes.
3) Insulin receptors
Antibodies to insulin or its receptors could be causes of diabetes since these would block insulin signalling.
4) NOT usually protein glycosylation observed with hyperglycemia: protein glycosylation is caused by diabetes. Antibodies to these could not cause diabetes.
- In the liver, Insulin normally acts to promote:
- FATTY ACID SYNTHESIS:Insulin is secreased when there is plenty of glucose and causes this glucose to be stored as glycogen and fat.
Insulin inhibits glycogen breakdown and promotes glycogen synthesis. Thus, blood glucose is stored as glycogen.
NOT: Gluconeogenesis: Since insulin is secreated when there is plenty of glucose, it woul dbe a useless positive-feedback loop for it to cause glucose synthesis. It actually inhibits gluconeogenesis while promoting glycogen synthesis.
- Endogenous insulin is delivered directly into the?
- HEPATIC PORTAL CIRCULATION: blood from the pancreas drain into the liver via the hepatic portal circulation. This is the system of veins which carries nutrients and normones from the digestive tract and pancreas to the liver for processing. the liver is normally exposed to concentrations of insulin which are 3-10 times greater than those in peripheral tissues. hence it is thought that insulin injected hear the skin might have a smaller effect on the liver and a greater effect on the rest of the body than endogenously synthesized insulin.
- Which hormones would exacterbate the state of diabetes mellitus?
- 1) Glucogon: Glucagon is the hormone of hunger. It does the opposite of nearly everything insulin does. Fro example, in the liver, it stimulates glycogen breakdown and release of glucose into the bloodstream.
2) Epinephrine: Epinephrine also stimulates glycogen breakdown in the liver. It helps to increase blood glucose during the sympathetic "fight or flight" response.
3) Glucocorticoids: Glucocorticoids stimulate gluconeogensesis. Cortisol actually causes muscle protein to be broken down and made into glucose in the liver. Muscle wasting and obesity result.
4) NOT INSULIN
- The sympathetic nervous system uses the following:
- 1) Motor neurons to innervate glands: Motor neurons are simply neurons that carry information from the CNS. "Motor" does not necessarily refer to a nerve that innervates a muscle.
2) Sensory neurons to innervate Blood pressure receptors
3) Interneurons to facilitate neural control
4) NOT motor neurons to innervate skeletal muscle: STriated skeletal muscle is innervated only by the somatic nervous system.
- What is necessary to allow an AP in an electrically stimulated neuron?
- 1) A concentration Gradient
2) A net negative charge in the axonal interior
3) NO ATP NECESSARY!
- AXON Characteristics
- 1) Abundance of microtubules and actin filaments: These are essential for axonal transport and cytoskeletal structure, respectively.
2) Presence of ion channels in the plasm membrane
3) Ability to transmit AP in one direction only.
4) NO protein-synthesizing machinery: Axons do not have a nucleus, ER, Golgi apparatus, or ribosomes.
- To achieve repolarization during AP:
- Na+ channels must close and K+ channels must open to facilitate rapid return to resting membrane potential. The depolarization that constitues the AP triggers both of these occurrences. The Na+ channels open very rapidly when the neuron first depolarized to threshold. then these channels are slammed shut very rapidly when teh AP spike occurs. Na+ channels = "fast channels". The K+ replolarization channels are opened by the AP spike too, but they take longer to open. In fact, they do not open until just the right time for repolarization to begin.
- The function of human chorionic gonadotropin (hCG) during pregnancy is to induce:
- THE CORPUS LUTEUM TO PRODUCE ESTROGEN AND PROGESTERONE: During the 1st trimester of pregnancy, hCG induces the corpus luteum to produce estrogen and progesterone. The hCG is derived from the fetal portion of the placenta, the chorion. Its function is to promote secretion of progesterone during the interval when LH secretion by the pituitary has ceased and progesterone secretion by the placenta has not yet begun.
-Atrophy of the corpus luteum occurs only in the absence of hCG
-LH surge is a part of the menstrual cycle and thus does nmot occur during pregnancy. In fact, hCG is necessary to stimulate the corpus luteum to secrete progesterone because of falling LH levels.The LH surge is induced by a gradual rise in estrogen levels.
-A drop in LH and FSH production occurs at the time of ovulation. The function of jCG is to substitute for these hormones in stimulating the production of estrogen and progesterone.
- The antigen-binding stie of the mouse anti-hCG is:
- A POCKET FORMED BY THE INTERACTION OF THE VARIABLE REGIONS OF A HEAVY CHAIN AND A LIGHT CHAIN. Antibodies are composed to 2 identical light chains and 2 identical heavy chains. Each chain has a constant and a variable region. Each antibody has 2 antigen binding sites, each one consisting of a pocket formed by the interaction of teh variable region of a heavy and a light cahin.
-FYI: the constant region is common to all antibodies of a particular antibody class (such as IgM). The binding site which is unique to a particular idiotype of antibody is formced by the interaction of the avariable region of one light and 1 heavy chain.
- To what part of the secondary antibody is the color producing enzyme bound?
- THE CONSTANT REGION: The constant region is not involved in antigen recognition, so it is available for enxyme conjugation without hindering the ELISA assay.
- Cholecystokinin functions in digestion to cause the release of?
- 1) Trypsionogen:Cholecystokinin causes the release of pancreatic enzymes a key example of which is trypsin stored as trypsinogen.
3) NOT Pepsinogen: This is released in response to stimulation by the vagus nerve.
- What is the function of the acid secreted by the stomach?
- 1) Breakdown of food: The low pH of the stomach can hydrolyze many food molecules
2) Activation of pepsinogen: Acid secreted by parietal cells has this function.
3) Elimination of bacteria swallowed with food
- In addition to inhibiting the digestive process, the sympathetic system also:
- Dilates the pupils, accelerates the heart rate, and stimulates glucose release from the liver, watery salvation, stimulating the heart and skeletal muscles, relaxing the bronchi, inhibiting digestive processes and therefore preparing us for fight or fly.
- The Sertoli cells, which produce Mullerian inhibiting factor are located in the:
- SEMINIFEROUS TUBULES: The Sertoli cells are the cells which support and nourish develiping spermatozoa. Since sperm develops in the seminiferous tubules, Sertoli cells must be located there. In fact, their cell bodies extend from the base of the tubule into the lumen. In addition to producing Mullerian inhibiting factor, they provide nutrients to the develiping sperm.
-The epididymis is where sperm mature
-Vas deferens: This is the duct through which sperm pass en route to the ejaculatory duct
-Corpus luteum: This is teh remnant of the ovarian follicle that is left behind after ovulation has occured.
-The mullerian ducts give rise to the fallopian tubes, the uterus, the cervix and the upper 3rd of the vagina in females.
- What would probably apply to an individual with a large deletion in the short arm of the Y chromosome?
- 1) He would be genetically male: Anyone with a Y chromosome is genetically male.
2) males are more likely to suffer from an X-linked recessive disease, because if they have an abnormal X chromosome, it is their only copy. Females have 2 X chromosomes, one donated by each parent and are thus very unlikely to have 2 copies of a defective X chromosome. Defects on the Y chromosome would not change this.
3) He would have differentiated ovaries
4) He would have a normal-appearing vagina.
Female development is the default, and that male evelopment only occurs when the Y chromosome is present. A large deletion on the short arm of the Y chromosome would likely disrupt the gene for H-Y atigen, which determines male development.
- Testosterone is produced by?
- Intersitial cells of leydig: They are the testosterone-producing cells, located in the testes, outside the seminiferous tubules.
FYI: Corpus luteum makes estrogen and progesterone
The Sertoli cells do not make testosterone, althought they modify it by conterting it to dihydrotestosterone.
- Extreme blood loss causes
- 1) A decrease in the glomerular filtration rate: The decrease in blood pressure lowers the hydrostatic pressure driving fluid fromt he glomerular capillary into the nephron. This is a direct result of the decrease in blood pressure and also an indirect result of hormonal reactions which constricts the afferent arteriole (supplying the glomerulus). This functions to reduce filtration pressure even more than it is already reduced by the general low blood pressure in order to conserve blood volume. The hormone responsible for constricting the afferent arteriole is angiotensin II. Angiotensin II also is the principal stimulus for the secretion of aldosterone. The level of angiotensin II, in turn, is determined by the level of renin, a hormone secreted by a part of the kidney which monitors contents of the blood and the urine.
2) An increase in ADH secretion: ADH is secreted in response to reduced plasm volume.
3) An increase in aldosterone: Aldosterone increases the blood pressure, which is just what is needed after blood loss.
- Long-term water deprivation has what effect?
- 1) Decreased glomerular filtration rate: Decreased water intake leads to decreased blood pressure which leads to decreased filtration, directly and via angiotensin II.
2) Increased secretion of ADH and aldosterone: Both ADH and aldosterone causes water retention.
3) Increased Na+ reabsorption: This results fromt he increased aldosterone.
- What is a relationship between ADH and aldosterone?
- ADH stimulated the synthesis of a tubular protien which acts as a channel, permitting H2O to cross cell membranes. This is how ADH has the effect of permitting water to flow according to osmotic gradients across an otherwise impermeable cell layer.
Aldosterone increases sodium reabsorption, which increases blood osmolarity, which in turns stimulates the release of ADH, but this is an indirect effect.
Aldosterone stimulates synthesis of a basolateral Na+/K+ ATPase which pumps Na+ out of the urine and K+ into the urine.
- In healthy people, secretion and reabsorption in the proximal tubule?
- CAN OVERCOME CONCENTRATION GRADIENT: The proximal tubule can absorb essentially all the glucose from the glomerular filtrate of a healthy person. To do so, concentration gradients much be overcome. It does not play a role in regulating plasma osmolarity. It functions to reclaim useful molecules such as glucose from the filtrate. The secretion and reabsorption of various substances must be independent of urinary flow so that it can be accomplished regardless of changes in flow.
- Breast development is stimulated by an increase in estrogen secretion. What hormone must increase in order for this to occur?
- GONADOTROPIN RELEASING HORMONE (GnRH):Estrogen secretion by the ovaries is under the control of gonadotropins (LH and FSH) secreted by the anterior pituitary. the production and release of the gonadotropins, in turn is under the influence of hypothalamic GnRH. Therefore, estrogen production and secretion is dependent on the secretion of GnRH.
TSH plays NO direct role in reproductive development.
Prolactin plays no role in the control of estrogen secretion and breast development, though it plays an important role later in inducing milk secretion.
Progesterone plays no role in promoting estrogen secretion.
- The seminiferous tubules are the site for:
- PRODUCTION OF SPERM: The seminiferous tubules are located in the testes and is the site for sperm production. Under the influence of RSH and testosterone, spermatogonia deveop into spermatozoa. Further maturation occurs in the epidiymis.
Testosterone is secreted by the interstitial cells of Leydig.
Maturation occurs in the epididymis.
The seminiferous tubules are the site of sperm production in the male. Fertilization occurs in teh fallopian tube, which is, of course, in the female.
- The increase in testicular size at puberty is a DIRECT result of the action of?
- 1) Lutenizing Hormone (LH): via stimulation of the interstitial cells of Leydig
2) Follicle Stimulating Hormone (FSH): via seminiferous tubule development.
Both hormones causes an increase in testicle size.
3) NOT Growth Hormone (GH): GH from the anterior pituitary stimulates somatic growth, particularly skeletal growth. It causes increases in the length of long bones until the epiphyses fuse at the time of puberty. It does not have a role in testicular development.
- A protein was isolated and found to act as a tyrosine kinase, an enzyme whcih attaches tyrosine resides to exposed hydroxyl groups on other proteins. This tyrosine kinase activity was constant. the same protein was present in normal cells but tyrosine ki
- THE PROTEIN IS NORMALLY CONTROLLED BY A PROTEIN WHICH BINDS GH AT THE CELL SURFACE:
GH and all the other pituitary hormones are peptide hormones, which function by binding to a cell-surface receptor; this in turn leads to changes in the activity of intracellular proteins via signal transduction. Tyrosine kinase activity is an example of a signal transduction system. In normal cells, kinase activity is not observed unless cells are exposed to hormone, indicating the kinase is regulated by a GH receptor.
- The hormone that stimulates teh production and release of Growth hormone is derived from what organ?
- HYPOTHALAMUS: the primary stimulus for GH secretion is GH-releasing hormone derived from the hypothalamus.
FYI: GH itself comes from the anterior pituitary.
The posterior pituitary only stores ADH and oxytocin from the hypothalamus.
- Bowman's capsule: Ultrafiltration, due to the high hydrostatic pressure of blood in the glomerular capillary bed. 90% serum fluid enters bowman's capsule.
-The filtrate is composed of:
2)Small solutes: salts, nitrogenous wastes, glucose, amino acids, vitamins
- Proximal tubule: Permeable to salts, urea and water. The fluid within is isosmotic to plasma.
-Substances actively transported out of the tubule, or reabsorbed:
2) Amino Acids
4) Water passively follows
-Substances ACTIVELY transported into the tubule or excreted:
2)H+: H+ excretion results from the action of carbonic anhydrase, which converts CO2 to H2CO3 which in turn dissociates to H+ and HCO3-. (Every H+ secreted an HCO3- is absorbed)
Descending limb of Loop of Henle
- Descending limb of Loop of Henle: The descending limb is permeable to water and moderately permeable to salt and urea. Urine becomes HYPERTONIC b/c water flows out of the tubule, drawn by the high solute concentration of the inner medulla.
Thin ascending limb of Loop of Henle
- Thin ascending limb of Loop of Henle: impermeanble to water but permeable to Na+, Cl- and Urea. these ions flow out of the tubule into the interstitium. Increase in interstitial osmolarity and a decrease in tubular fluid osmolarity.
Thick ascending limb of Loop of Henle
- Thick ascending limb of Loop of Henle: Impermeable to Urea and water. Thick b/c cells are metabolically-active tall columnar cells. They use energy of ATP to ACTIVELY pump Cl- out of the tubular fluid. ha+ follows this chloirde, trawn into the interstitium by the electrical potential created by the movement of alrge amounts of Cl-. The result is a decrease in the osmolarity of the tubular fluid, and a great increase in the solute concentration of the medullary interstitium.
Distal Convoluted Tubule and Collecting Duct
- Distal Convoluted Tubule and Collecting Duct: Fluid arriving at the distal tubule is hypotonic to original filtrate arriving in the proximal tubule. The permeability of the distal nephron to water, urea, and salts is under hormonal control. Final modification sof Urine. ADH and Aldosterone are prime determinants of urinary volume and osmolarity. ADH causes reabsorption of water by making the distal tubule premeable to water. B/c of high solute concentration of the inner medulla, water will flow out by osmosis out of the tubule when the tubule becomes permeable. The solutes concentrated in the medulla are NaCl, derived from the pumping of the thick ascending limb, and urea which is concentrated in the medulla by a complex mechanism. Aldosterone causes the reabsorbtion of Sodium and the excretion of potassium. The resulting increase in serum sodium concntration results in thirst, water retention, and increased blood pressure.
- Active transport of ions occurs in what parts of the nephron?
- 1) Proximal tubule: Na+, K+, H+ ions are actively transported in the proximal tubule.
2) Thick ascending limb: Mostly responsible for setting the NaCl osmotic gradient in the medulla by active transport alone.
3) NOT thin ascending limb: permeable to ions. They flow by diffusion here NOT active transport.
- In order for the loop of Henle to make filtrate more concentrated than plasma, what must be true?
- THE LOOP OF HENLE MUST GO DEEP INTO THE RENAL MEDULLA, ADN THE MEDULLA MUST HAVE A VERY HIGH SOLUTE CONCENTRATION: The key to concentrating urine is that the ascendign and descending limbs both pass throught the medullary osmotic gradient and that they are close together to achieve a countercurrent exchange system with the vasa recta.
- In which regions of the nephron is the urine hypertonic compared to plasma?
- 1) DESCEDNDING LIMB OF THE LOOP OF HENLE: urine becomes hypertonic in the descending limb.
2)THE COLLECTING DUCT IN THE PRESENCE OF ADH: ADH causes water to be reabsorbed in the distal tubule and collecting duct.
3) NOT Upper part of the tick ascending limb of the loop of Henle: The thinck ascending limb, ions are pumped out, but water is left in filtrate, creating hypoosmotic filtrate.
- The thick ascending limb of the Loop of Henle
- 1) IS NOT PERMEABLE TO WATER OR UREA
2)CREATES HYPOTONIC URINE: The active transport of chloirde out of the tubule creates a less concentrated or hypotonic, urine.
3)WOULD BE EXPECTED TO HAVE MANY MITOCHONDIA. Since the thick limb uses large amounts of ATP for active transport, it would be expected to have ATP factories, or mitochondria.
- What hormones play a role in the regulation of kidney function?
- 1) ADH: H20 reabsorption
2) Aldosterone: Na+ reabsoprtion
3) Parathyroid hormone: Most important action on the kidneys is promoting reabsorption of Ca2+; it also promotes excretion of PO42-.
- A low protien diet is associated with a redution in the ability of the kidney to concentrate urine. Why?
- Little urea is produced: Urea is a by=product of protein metabolism. It is a carrier of nitrogen which can be exreted. the high concentration of the urea is the renal medulla is essential for the reabsorption of water in response to ADH.
- The drug acetazolamide inhibits the action of carbonic anhydrase in the kidney, which catalyzes the reaction: CO2 + H2O--> H2CO3. What effect would the drug have on kidney function?
- DECREASE PLASMA pH: The H+ excretion results from the action of carbonic anhydrase, which converts CO2 to H2CO3 which in turn dissociates to H+ and HCO3-. Hence for every H+ secreted, an HCO3- is absorbed. Therefore, it can be inferred that without carbonic anhydrase, the proximal tubule's ability to secrete H+ is inhibited; increased urine pH reults. Another consequence is that if H+ is not secreted into urine, then it will remain in the plasma, thereby decreasing plasma pH at the same time that urine pH increases.
- What solutes are responsible for the osmotic gradient in the renal medulla?
- UREA and NaCl: The solutes concentrated in the medulla are NaCl derived from the pumping of the thick ascending limb and urea, which is concentrated in the medulla by a complex mechanism.
- Calcitriol acts via:
- Changing the transcription of specific genes: Calcitriol is derived from cholesterol and is thus related to steroid hormones. Steroids and other small hydrophobic hormones act by hinding a receptor in the cytoplasm and diffusing into the nucleus to directly modify transcroption of particular genes.
- Hormones and Ca2+
- 1) Estrogen increases both Ca2+ deposition in bone and Ca2+ uptake by the kidney and the intestine.
Calcitonin's (made in the thyroid by the C cells) primary function is to lower the level of Ca2+ in the blood. It does this by promoting storage of Ca2+ in bone and by inhibiting intestinal and renal uptake of Ca2+.
Parathyroid hormone decreases the amt of Ca2+ in bone, but it increases the amt in the body by promoting renal and intestinal uptake. The function of parathyroid hormone is simply to raise the concentration of Ca2+ in the blood. Therefore secreted when Ca2+ is low and serves to increase its concentration.
-Both calcitonin and parathyroid hormone are secreated in response to changes in serum Ca2+ concentration in the blood.
- Cells involved in Bone synthesis:
- 1) Osteoclasts are derived from the bone marrow. They are related to the blood-borne monocyte (the macrophage's precursor). All the cells of the blood are made in the bone marrow.
2) Oxteocytes are immobilized in spaces called lacunae which are connected by channels called canaliculi. They are derived from fibroblasts. All of the cells involved in secreting the extracellular matrix are derived from the fibroblast. This includes osteoblasts. They have lost the capability to divide.
- Osteoblasts: A cell from which bone develops; a bone-forming cell.A cell that makes bone. It does so by producing a matrix that then becomes mineralized. Bone mass is maintained by a balance between the activity of osteoblasts that form bone and other cells called osteoclasts that break it down.
Osteoclast: A large multinucleate cell found in growing bone that resorbs bony tissue, as in the formation of canals and cavities. A cell that nibbles at and breaks down bone and is responsible for bone resorption.
Osteoclasts are large multinucleate cells (cells with more than one nucleus) that differentiate from another type of cell called a macrophage.
Osteocyte: A branched cell embedded in the matrix of bone tissue. A bone cell.
- What are the features of epidermal layer of the skin?
- 1) It consists of stratified squamous tissue
2) Tt consists of closely packed cells arranged in several layers Stratified squamous epithelium is made up of layers of closely-packed flat cells.
3) Only its inner most layer of cells reproduces itself. Only the basal layer, or stratum germinativum, undergoes cell division. As new cells are produced here, the old cells are pushed outward, become keratinized, and eventually die and are sloughed off.
FYI: It is false that the epidermis is composed of fibrous connective tissue.
- Women treated over a long period of time with realtively large doses of estrogen do not ovulate. This is porbably due to:
- INHIBITION OF GONADOTROPIN SECRETEION BY ESTROGEN: Estrogen acts at the hypothalamic and pituitary levels to inhibit the secretion of GnRH from the hypothalamus, and FSH and LH from the anterior pituitary. This is a classic negative feedback loop.
- Ovulation is most directly caused by:
- A PEAK IN LH SECRETION:
The preovulatory LH surge is essential for ovulation.
- The Preovulatory decline of FSH is due to:
- NEGATIVE FEEDBACK OF ESTRADIOL: The preovulatory decline of FSH is due to the increaseing concentration of estradiol. Estrogen inhibits FSH by negative feedback.
- In the absence of pregnancy, menstration normally occurs. this is due to the decline of which of the following hormones required for maintenace of the endometrium?
- PROGESTERONE AND ESTRADIOL: Progesterone is responsible for the changes in the endometrium that result in the secretory phas, namely an increase in vascularization and the storage of lipids and glycogen. Estrogen is responsible for the proliferative phase of the endometrial cycle and is also necessary for the secretory phas along with progesterone.
FYI: FSH, LH, and hCG act on the ovaries NOT the endometrium.
- Both estradiol and progesterone are produced by?
- 1) Corpus Luteum
The ovarian follicle produces estradiol but not Progesterone.
- The stimulus for FSH and LH production and secretion is the pulsatile release of gonadotropin releasing hormone (GnRH). Which of the following structures produces GnRH?
- HYPOTHALAMUS: Produces GnRH. It produces most of the releasing and inhibiting hormoes that act on the anterior pituitary.
FSH and LH are produced in the anterior pituitary.
The posterior pituitary is the site of release of ADH and oxytocin.
The Pineal gland is thought to secrete melatonin. It has no significant role in the menstral cycle.
- Primary and secondary antibody response and Carrier effect
- Primary Response: When the immune system is exposed to an antigen, which is a substance that it recognizes as foreign, both helper T-cells and B-cells bind to the antigen. The helper T-cells help the B-cells to produce antigen-specific antibodies that bind to the antigen and facilitate its destruction.
Secondary response: Meanwile, there's another group of B-cells andhelpter T-cells that become primed to the antigen- they remember it- so if the immune system is re-exposed to the same antigen, its second response will be greater and quicker. The helper T-cells that are primed to the antigen will stimulate the proliferation of the primed B-cells into antibody-secreting B-cells.
Carrier effect: someetimes the antigen is so small that the immune system doesn't even notice it, which means that this antigen will not elicit anibody production. But f you take this antigen, complex it with a larger antigen, and inject an animal with it, then upon reinjection, there will be antibody produced specific for the tiny antigen at a level comparable to a secondary response. The tiny antigen is called a hapten and the larger antigen which is usually a foreign protein, is known as a carrier. When an animal is primed with a hapten-carrier complex, you don't get any anti-hapten antibody production. Rather, you get B-cells that are primed to the hapten and helper T-cells that are primed to the carrier. If the helper T-cells were able to recognize the hapten, then you'd get anti-hapten antibody production immediately. WHen the animal is reinjected, or boosted, with the same hapten-carrier complex, THEN you get anti-hapten antibody production.
- 1) A nuclear envelope: Fungi
2) An RNA genome: Virus
2) Genes with introns: Virus, fungi
3) Ribosomes: Bacteria, fungi
5) Meiotic cell division: Fungi
6) RNA-dependent DNA polymerase: Virus
7) Krebs cycle: Bacteria, Fungi
8) DNA-dependent DNA polymerase: Bacteria, Virus, Fungi
- catabolic reactions
- catabolic reactions: reactions that break down molecules to supply energy
- anabolic reactions
- Anabolic reactions:synthesis of macromolecules.
- Digestion: breakdown of polymers (polypeptides, fats, starch) into their duilding blocks. This breakdown is accomplished by enzymatic hydrolysis. Food contains vitamins, which are not susbstrates, but serve a catalytic role as enzyme cofactors or prosthetic groups.
- GI tract
- Gastrointestinal tract: digesttive tract, the alimentary cancal, or gut. Mouth --> anus.
Tube is derived from the cavity produced by gastrulation during embryogenesis. The anus is derived from the blastopore. The inside of the gut is the GI lumen.
GI muscle is SMOOTH muscle: functional syncytium. Has own nervous system, enteric nervous system.
- Liver: deals with hydrophobic or large waste products which cannnot be filtered out by the kidney. The kidney can only eliminate small hydophils dissolved in plasma.
Synthesizes Urea which is released into the blood stream. Excess nitrogen can be converted to urea because free ammonia is toxic.
- loop of Henle
- Loop of Henle is a coutercurrent multiplier that makes teh medulla very salty. It facilitates water reabsorption fromt he collecting duct. This is how the kidney is capable of making urine iwth a much higher osmolarity than plasma.
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