bio ch 32
Terms
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- microbes
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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 - pathogens
- disease-causing organisms
- What are the 3 major forms of protection against disease in the human body?
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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
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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
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-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
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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
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(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
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-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 - histamine
- chemical that relaxes smooth muscles of blood vessels for increased blood flow (more macrophages and neutrophils)
- cytokines
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chemicals released by macrophages to help with inflammatory response
-communicate w/ WBC-come out of capillaries, blood clottin - pus
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mixture of dead bacteria, tissue debris, WBCs (dead/alive)
-pus may form if injury was caused by dirty object - Nonspecific Internal Defenses: fever
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-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
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1. recognize the invader
2. attack it
3. remember it, to prevent future infection - Immune System
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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 - antigen
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-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 - anitbody
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-proteins produced by B cells
-combine w/ a specific antigen & mark it for destruction
-Y-shaped - T cell receptors
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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)
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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)
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- 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
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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 - antibiotics
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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
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anti viral drugs
-block the ability of newly formed virus particles from bursting out of host cell - vaccination
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-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
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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
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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
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-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
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-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
anemia
rheumatoid arthritis
lupus -
-islet cells of pancreas attacked
-myelin shealth is attacked
-RBCs attacked
-joint cartilage is attacked - Severe combined immune deficiency (SCID)
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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)
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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) - cancer
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-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 - tumor
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-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
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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
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-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