Biology Unit 12
Terms
undefined, object
copy deck
- Why are muscle fibers striped?
- Because myofibrils are striped
- sacromere
- repeating unit, from z line to z line
- myosin
- thikc filament, A band (dark)
- actin
- thin filament, I band (light)
- H band
- area created when muscle is relaxed and is and area where myosin is present but not actin
- thick filament structure
- many myosin proteins wound together. each myosin protein has a thickened region on the head
- thin filaments
- actin protein molecules twisted into a double helix
- tropomyosin
- proteins that block binding sites on actin at low calcium concentrations, the muscle is relaxed
- troponin
- calcium binds to this protein which causes a conformational change in tropomyosin, allowing myosin heads to bind to actin and cause muscle contraction
- sacroplasmic reticulum
- stores calcium, muscle fiers
- somatic motor neurons
- nerve cells found on skeletal muscle
- synapes
- made by axons of somatic motor neurons with many fibers
- motor unit
- the set of muscle fibers in contact with (innervate by) all axonal branches of a given motor neuron
- recruitment
- the numbers and sizes of motor units vary and variation allows for gradations in motor movement (needed for coordination)
- fine degree of control
- few muscle fibers per neuron (smaller motor units)
- muscles that need power and force
- require large numbers of fibers per neuron (larger motor units), leg muscles
- selective activation
- most muscles contain a variety of motor unit sizes
- weak/strong contractions
- activation of a few small motor units/additional motor units are activated
- type I fibers
- slow twitch, muscle in the leg=sustained contraction, low fatigue, high number of capillaries, respiratory enzymes, myoglobin, mitochondria, red fibers
- type II fibers
- fast twitch, eye, high fiber thickness, low number of capillaries, mitochondria and myoglobin, hence white fibers
- intermediate muscles
- between fast and slow, calf muscle
- Where do skeletal muscles at rest obtain energy from?
- aerobic respiration
- During exercise
- anaerobic respiration occurs for 45-90 seconds, then glycogen and blood glucose are used
- intensity of exercise level varies with
- individuals capacity for oxygen uptake
- muscle fatigue
- decrease in muscles ability to generate force, directly related to high lactic acid formation
- weight training does what to cells?
- increase cell size, called hypertrophy
- cardiac muscle
- makes up heart, cells interconnect and link (at structures called intercalated discs) creating a single, functional unit, the myocardium
- smooth muscle
- no striations, surround vessels and organs. many are under involuntary, neural control
- what composes the overall digestive system?
- alimentary canal and solid organs
- innermost layer
- mucose, lines the lumen (opening). functions vary with location (ex. esophagus-lubrication; small intestine-absorption)
- 2nd layer
- submucosa, contains blood and lymph vessels
- 3rd layer
- muscalaris, contains external muscles for support (circular, longitudinal, oblique-stomach only)
- outermost layer
- serosa (aka peritoneum), a thin layer of connective tissue surrounding the abdominal cavity
- mechanical digestion
- teeth breakdown the food forming a ball (bolus) of food
- chemical digestion
- saliva and enzymes secreted from salivary glands. polysaccharides broken down into dissacharides by salivary amylase
- epiglottis
- blocks the trachea
- food moves through the alimentary canal by
- peristalsis contraction of smooth muscle
- STOMACH function
- breakdown (AKA digestion, AKA hydrolysis), partial breakdown of protein
- gastric pits of mucosal cell layer contain gastric glands that secrete
- *
- parietal cells secrete
- HCl
- chief cells secrete
- pepsinogen, breaks down protein
- chyme
- solid food is converted to a semi-liquid called chyme
- pyloric shincter
- terminal digestion of carbs, lipids, proteins occur and digestion products (monomers of these molecules) are absorbed
- SMALL INTESTINE functions
- terminal digestion and absorption
- sections of the small intestine
- duodenum, jejunum, ileum
- accessory (solid) organs produce HCO3 which
- neutralizes acid as chyme enters the duodenum and jejunum
- pancreas secretes
- digestive enzymes
- liver secretes
- bile which stimulates the gall bladder to secrete bile (helps breakdown)
- these organs secrete into ducts
- that empty into the duodenum
- microvilli
- small cytoplasmic finger-like projections, in the small intestine, epithelial cells of the mucosa
- LARGE INTESTINE (colon) function
- concentration of waste, reabsorption of water, ions, vitamin K
- cecum and appendix are
- vestigial structures
- three main portions of the large intestine
- ascending, transverse, descending (rectum)
- e coli function
- consume undigested food and secrete amino acids and vitamin K for absorption
- fecal matter
- dead bacteria, undigested food, plant fibers, cell debris
- PANCREAS
- *
- exocrine organ
- secretes enzymatic fluid into duodenum through pancreatic duct
- endocrine gland
- islets of langerhans. cells in this region secrete important hormones
- alpha cells secrete
- glucagons
- beta cells secrete
- insulin, together regulate blood glucose levels
- LIVER AND GALL BLADDER
- *
- secretions
- (exocrine)=bile pigments and salts
- liver function
- produces bile, storage and/or break-down of glycogen, synthesis of glucose, production of blood plasma proteins, destruction of RBCs, detoxification of drugs and alcohol, regulates lipid metabolism, involved in lactic acid metabolism
- gall bladder
- stores bile
- Gastrin
- hormone which triggers release of HCl and pepsinogen when food is seen
- CCK
- hormone secreted in response to fat. stimulates addition of bile to duodenum
- CHAPTER 49, circulation
- *
- Open circulatory system
- circulating fluids (blood) and extracellular fluid body tissues (aka interstitial fluid aka lymph) are mixed collectively called hemolymph
- closed circulatory systems
- blood is enclosed within vessels and circulated by a pump, the heart
- countercurrent heat exchange
- cold, incoming blood from surface areas (skin) is warmed by warm blood from torso because arteries and veins are right next to each other
- constriction of vessels
- vasoconstriction, low blood flow, low heat loss. dilation of vessels (vasodialtion)-high blood flow, high heat loss
- artery
- leaves the heart
- vein
- goes to the heart
- Inner artery later
- endothelium
- middle artery layer
- smooth muscle dilates or contracts to accomodate pressure
- outer
- connective tissue (collagen) for support and elasticity
- pulse
- expansion and contraction of elastic, arterial wells. (evens out the blood spurts as the blood leaves the heart under high pressure)
- veins function
- transport, contain some tissues, but not as thick as artieries
- Why can veins move easily to the heart?
- thin walls, large lumen (vessel openings) cause a low resistance to blood flow
- capillary function
- exchange
- capillary composition
- madae of endothelial cells, only 1 cell layer thick (for diffusion)
- enxtensive branching causes...
- low speed of blood flow for more efficient exchange
- small vessel diameter means...
- high resistance to flow
- 3 ways to exchange across capillaries
-
1. across cell membrance of endothelial cell
2. endocytosis/exocytosis
3. pores and clefts (between cells-except in NS) allow water and ions to cross - exchange is based on
- osmotic pressure (due to osmotic concentration) and hydrostatic pressure (pressure of fluid in vessel)
- lymphatic system functions
- drainage of extracellular fluid, part of immune system, absorption of fat from intestines
- pathways of the lymphatic system
- fluid in extracellular spaces goes to lymph pores (lacteals) goes through lymph system to heart, lymph collects in thoracic duct and is returned to bloodstream via syperior vena cava (in neck)
- transport in lymphatic system
- aided by body (skeletal) muscle contraction and smooth muscle contraction in vessels
- arteries
- leave the heart
- veins
- go to the heart
- cardiac output
- CO (volume of blood moved per contraction)
- blood flow
- both atria fill simultaneously, both atria contract, both ventricles fill, both ventricles contract
- pacemaker
- sino-atrial (SA) node. bundle of tissue in wall of right atrium
- atrio-ventricular node (AV node)
- a bundle of tissue between the right atrium and right ventricle
- bundle of his and Purkinje fibers
- conducting nerve fibers that go from AV node around both ventricles
- heart sounds: lub
- atrial ventricle valces closing
- dub
- valves between ventricle and arteries closing
- arterial blood pressue is determined by...
- total volume of blood being pumped(C0) and resistance to blood flow
- blood pressue measured as:
- (systolic pressure=ventricular contraction)/(diastolic pressue=atrial filling)
- baroreceptors
- receptor cells in carotid arteries (neck) and in arch of aorta that detect changes in arterial pressure
- ADH
- thirst stimulates release of ADH from posterior pituitary. Cause kidneys to keep more water in blood, less excited, raises blood volume
- Aldosterone
- kidneys experience decreased blood flow and release angiotensis II causing vasoconstriction. Causes stimulation of adrenal cortex, releasing aldosterone. net result: high sodium and water retention in blood
- atrial natrioretic hormone
- opposite action of aldosterone. high blood volume stretches right atrium which release atrial natriuretic hormone. action=low sodium, water in blood
- nitric oxide
- a gas that causes smooth muscle to relax, vessels dilate, blood flow increases.
- *
- *
- fick's law
- diffusion rates across membranes vary with surface area, concentration differences (gradients) and distance
- barometric pressure
- pressure of all gases in atmosphere at sea level or atmospheric pressure=760 mm Hg
- Where are gills located
- between mouth and operculum (flap)
- What does opening and closing of the mouth do?
- opening the mouth forces out water into cavity, closing mouth forces water over gills
- Why were gills replaced by lungs?
-
1.complex structure of the gills could not be supported by air (requires water to buoy it up)
2.The large surface area of gills would cause rapid decline in water from gills to air - amphibians breathing
- have low surface area and positive pressure breathing. supplement oxygen uptake with diffusion across skin (cutaneous)
- all other terrestrial vertebrates
- negative pressure breathing (higher pressure outside the body, gases want to come in)
- Mammals pathway
- O2 in nose and mouth ->
- pharynx ->
- larynx ->
- trachea ->
- split into two lungs, bronchi ->
- bronchioles ->
- aluedi, lined with capillaries
- Why do birds have the most efficient respiration?
- cross-current flow of air and blood plus unidirectional air flow as a result of air sacs allow this to happen
- mechanical control of breathing
- breath (inhalation or inspiration) causes intercostals and diaphragm to expand increaing the volume in the thoracic or chest cavity. pressure is higher outside (negative pressure) so air rushes in
- exhalation
- relaxation of muscles and diaphragm
- oxygen is carried in the blood by
- the tetrameric (4 chain) protein hemoglobin (Hb)
- HB + 4O2 yields
- oxyhemoglobin
- binding to Hb involves
- allosteric effect (AKA conformational change in Hb protein aka cooperativity)
- The Bohr effect
- when CO2 levels are high, acidity increases
- Tissues
- increase CO2, increase H+, Hb release O2
- Lungs
- decrease CO2, decrease H+, Hb binds CO2
- hemoglobin binding sites can also bind
- NO, affects blood flow, and CO leads to irreversible competitive inhibition and death