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bio ch 32


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-microscopic organisms
-some microbobes are parasitic (live in &/or replicate or reproduce in a host organism)
Ex. bacteria (e.coli), viruses (HIV, SARS, Ebola), Fungi, Protists, worms
disease-causing organisms
What are the 3 major forms of protection against disease in the human body?
nonspecific external barriers-try to keep pathogens from entering body
nonspecific internal defenses-cells & chemicals that take action against any foreign invader(kill, repel)
-immune response-immune cells that attack specific foreign particles "remember" it for the future
Nonspecific External Barriers: skin
surface of skin is dry, dead cells (not nutritious, dry)
-skin cells slough off frequently-constantly removing microbes that may have landed on skin
-sweat, oil, and ear wax contain natural antibiotics
Nonspecific External Barriers: mucous membranes
-surround eyes, line digestive, respiratory, and urogenital tracts
-secrete musuc and tears (both contain lysozymes: antibacterial enzymes)
*musus traps microbes in mouth and nose
-lining of respiratory tract contains cilia-"sweep" the microbes up & out so the debris can be removed by coughing or sneezing/or swallowed & digested
Nonspecific External Barriers:
other secretions
harmless bacteria of digestive tract- they secrete chemicals that kill harmful bacteria and fungi
vaginal secretions(acidic) & vaginal mucus-trap and kill some microbes
urine-acidic & inhibits bacterial growth
Nonspecific Internal Defenses: Phagocytic cells
Macrophages and Neutrophils-travel through the blood
-can move through capillary walls
-destroy invaders by engulfing and digesting them
-macrophages also eat dead & dying cells produced by natural tissue replacement so they don't leak harmful chemicals)
Nonspecific Internal Defenses: Natural killer cells
(WBCs) kills bosy cells that have been infected, or become cancerous
-recognize surface proteins on viuses & abnormal molecules on outside of cancerous cells
-secrete enzymes that attack cancerous or infected cells
-secrete enzymes that make holes in cell membranes
Nonspecific Internal Defenses: inflammatory response
-local response to bodily injury
-characterized by phagocytosis of foreign invaders & dead tissue by WBCs & natural killer cells
-injury site is "walled off" by clotting fluids from the blood
-causes: mucus membranes to leak fluids, injured tissue to get red, swollen, warm, pain to guard & protect area while its healing, mast cells to release histamine, release of cytokines, formation of pus
chemical that relaxes smooth muscles of blood vessels for increased blood flow (more macrophages and neutrophils)
chemicals released by macrophages to help with inflammatory response
-communicate w/ WBC-come out of capillaries, blood clottin
mixture of dead bacteria, tissue debris, WBCs (dead/alive)
-pus may form if injury was caused by dirty object
Nonspecific Internal Defenses: fever
-increase in body temp.
purposes: slowing the repro. by bacteria (& other microbes), speeds up production of WBCs, increases production of interferon(a cytokine that reduces viral infection)
Cause: 1. macrophages release a cytokine called endogenous pyrogens 2. cytokine travels in blood to hypothalamus causes increase in body temp., shivering, lowers iron content in blood because bac. needs FE to repro.
Immune Response
1. recognize the invader
2. attack it
3. remember it, to prevent future infection
Immune System
a "cellular" system that consists of:
lymphocytes-specialized WBCs
chemical antibodies
lymph nodes, thymus, spleen, blood
T cells
B cells
T cells- originate in bone marrow, but they differentiate & develop in thymus
B cells- come from bone marrow
-molecule that stimulates the production of an antibody
-usually a protein or polysaccharide
-antigens are found on surface of microboes or cancer cells, or incorporated into membrane of virally infected cell, or dissolved in blood
-proteins produced by B cells
-combine w/ a specific antigen & mark it for destruction
T cell receptors
on surface of T cells
-bind to antigen & trigger immune response but they do not directly contribute to destruction
*human immune system randomly makes millions of antibodies & T cell receptors they just wait to bind to a possible antigen
Major histocompatability complex (MHC)
a collection of proteins on a human's cells. they are unique for each person
-transplane patients-take immunosuppressant drugs
-humans develop an immunity to their own cell surface proteins early in life by killing off out immature immune cells
Humoral Immunity (Antibody-Mediated Response)
- works best on toxins, bacteria, fungi, parasites
- carried out by B cells
1. infection occurs
2. a few B cells (w/ correct antibodies) bind to antigens on the surface of foreign particle/invader)
3. Antibody-antigen binding causes B cells to divide into clones of original B cells-clonal selection
4. Cloned cells differentiate into memory B cells & plasma cells
5. humoral immunity occurs because-circulating antibodies find foreign molecules-to inactivate them-antibodies may cover surface of invader that marks the invader for destruction (eaten by macrophages) - antibodies may bind microbes together in a clump so its easier for macrophages to eat them
6. complement system
memory B cells
WBCs that remain in blood to provide future immunity to same antigen by producing more plasma cells if needed
plasma cells
WBCs that produce and secrete antibodies cells make lots of ER, where specific antibody proteins are formed, then released. (Usually only last a few days)
complement system
(proteins) bind to stems of antibodies, starting a series of reactions that cause phagocytes to eat or it might form holes in plasma membrane to kill cells
Cell-mediated immunity
carried out by T cells
-effective against viral infections
helper T cells- help other immune cells (T cells , B cells) recognize and act against antigens
cytotoxic T cells- release proteins that break down plasma membrane of infected, transplanted, or cancerous cells only last a few days
memory T cells- provide future immunity to the same antigen by producing more cytotoxic T cells when/if same antigen appears
slow the growth and reproduction of bacteria, fungi, protists
-allow cells of the human immune system to out number & attack invading cells/bacteria
neuramindidase inhibitors
anti viral drugs
-block the ability of newly formed virus particles from bursting out of host cell
-administration of weakened (attenuated -> sometimes altered part of dead particle) or dead microbes to confer immunity
-may be given orally (in form of liquid (polio)/edible (banana), injected (needle), or administered using a gene gun (spraying fold drops coated w/ DNA)
Vaccination Timeline
1000 A.D.- people exposed themselves to smallpox deliberately India, China, Africa
1796-Edward Jenner inoculated child with pus from cowpox lesions, then smallpox lesions, then smallpox lesions
-smallpox has been eradicated globally, but smallpox virus still exist: CDC (Atlanta), Russia
-Vaccinations cause a mild immune response to an antigen, fever...producing some memory cells that are going to protect you in the future
Influenza vaccine
new vaccine must made each year because flu viruses are retroviruses (contain RNA), so they can mutate rapidly
-flu virus outbreaks are tracked globally, then 3 strains are identified, combined, and grown in chicken eggs
-sometimes human flu viruses mutate greatly, & combine (genetically) w/ bird flu inside pigs so flu virus transfews to human
-potential epidemics or pandemics may occur if flu mutates greatly, or combine w/ animal flu viruses
-people may die from seconday infections due to weakened immune system
allerigies & allergens
immune response to harmless antigens & harmless antigens that trigger immune response
Allergic response
-antigen enters body & gets recognized by B cell
-B cell carries antibody to molecules on antigen's surface, B cells form plasma cells
-plasma cells produce "allergy antibodies"-which bind to mast cell
-mast cells release histamine causing inflamation, "leaky" capilarries, mucus secretion, sneezing, coughing, watery eyes
Anaphylactic shock
itching, swelling of airways, hives...
Autoimmune disease
-disorder that occurs when immune system produces antibodies against the body's own cells
-causes unknown, but possibly due to some foreign invader that hast surfaceantigens similarto those of body itself
juvenile-onset diabetes
multiple sclerosis
rheumatoid arthritis
-islet cells of pancreas attacked
-myelin shealth is attacked
-RBCs attacked
-joint cartilage is attacked
Severe combined immune deficiency (SCID)
few or no immune cells are formed(due to genetic defect), so immune system does not respond to invading particles-common infection can be fatal
(antibodies from mother protect baby for a few months)
-gene therapy using bone marrow and viral vectors that are injected back into patient may be helpful
Acquired Immune Deficiency Syndrome (AIDS)
caused by infection w/ HIV 1 or HIV 2 (retroviruses) so they mutate rapidly - difficult to make a vaccine
-the viruses kill helper T cells, therefore they can't differentiate into cytotoxic T cells & memory T cells
AIDS=T cell count of 200/ml of blood
AIDS patients usually die from opportunistic infections-take advantage when immune system is weak ex. pneumonia, kaposi's sarcoma(skin cancer)
-uncontrolled cell growth by undifferentiated cells
-natural killer cells & cytotoxic cells usually kill cancer cells because they have slighty different proteins on outside
-some cancerous cells do not have surface proteins so they are not attacked by immune cells
-some types of cancer can suppress the immune system
-some cancer cells reproduce so quickly that immune system cant keep up
-group of cells w/ uncontrolled growth
benign tumor(polyp)-located in one area
malignant tumor-spread to other areas of body-metastasis
Treatments for cancer
surgery-removal of cells(risk of spreading cancerous cells)
radiation-destroys cancerous cells and nearby healthy cells
chemotherapy-drugs kill rapidly dividing cells-including healthy cells: hair follicles (hairloss);intestinal lining cells (nausea)
experimental treatments, recently developed treatments for cancer
-cancer vaccines
-stimulation of immune system to attack cancer cells
-use of antibodies specifically designed to recognize tumor cells (target)-so the drug or radioactive molecules go only to cancerous cells

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