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micro exam 3, study guide
Terms in this set (67)
What major body sites are heavily colonized by microbes? Are your born with these microbes?
The major sites are : mouth, nasal cavities, throat, stomach, intestines, urogenital tracts, and skin and these microbes begin at birth
What re the common genera of bacteria found on the skin, in the throat, and in the intestines?
Skin: corynebacterium, propionibacterium, and staphylococcus
Throat: Staphylococci, streptococci, diptheriod bacilli, gram-cocci
Intestines:Bacteroidetes,fimicules,proteobacteria, NO PROTISTS
What parts of the body do not have normal flora bacteria?
The inside of the uterus, central nervous system, blood, lower bronchi and alveoli, liver, spleen, kidneys, and bladder
How does plaque form in the teeth? what type of bacteria cause dental cavities? Are they aerobic or anaerobic organisms?
Dental plaque is formed when microbial cells form a biofilm on the teeth. The main purpose bacteria that causes dental cavities are Streptococcus mutants which re anaerobic and gram positive. If you looked at a gram stain of dental plaque you would see G+ cocci, G- cocci and res, and G+ rods and filaments. Mouth contains diverse aerobic and anaerobic organisms.
Why does eating a high sugar diet contribute to dental cavities?
The bacteria that is attached to the biofilm on your teeth(S mutant) ferments glucose (sugar) into lactic acid which damages the enamel of the teeth
Why is the lower respiratory tract typically microbe-free?
Ciliated pseudo stratified columnar epithelium, produce mucus, which traps particles and pathogens. The cilia in the lower respiratory tract microbe-free. The particles must be smaller than 10 um to get in.
What is the importance of vaginal Lactobacillus in healthy adult women?
Vaginal lactobacillus acidophilus is important because it ferments glycogen which creates lactic acid. The lactic acid produced maintains the slight acidic ph(-5) which is needed for protection purposes.
What causes UTI? Are men or women more susceptible to UTI's and why?
Proteus mirabilis and E. coli cause UTI's. Women are more likely to got UTI's than men because women have shorter urethras than men and the urethra meatus of women is closer to the opening of the anus.
Describe the properties of microorganisms that grow well on the skin. What determines whether or not an organism will colonize a body site?
The microenvironment (dry skin, moist skin, sebaceous skin) determine whether or not an organism will colonize a body site?
What does Clostridium difficult cause? What are the basic characteristics of this organism that help it cause disease?
Clostridium difficult causes diarrhea, severe abdominal pain, and fever, inflammatory lesions, and bowel perforations. It is a spore-former and antibiotic resistant bacteria, infections most often occur following an antibiotic treatment, it is an opportunistic infection caused by low counts of E. coli.
What is a probiotic? How does it differ from a prebiotic? Give an example of a probiotic. What are the name of some of the genera found in a probiotic?
Probiotic is a living microorganism that when administered in adequate amounts confer a health benefit on the host, suppresses get to urogenital disturbances. Prebiotics are capsules containing the nutrients necessary for the bacteria usually carbohydrates that are not absorbed or broken down but the human digestive tract.
Probiotic example is yogurt. Prebiotic example is usually carbohydrates.
Genera found in probiotics are: Bifidobacterium and Lactobacillus
What does it mean on a label that says "contains active culture"?
it contains a live and active bacteria culture within it. It is a probiotic
What causes lactose intolerance and its symptoms? What other things do fecal bacteria do?
Lactose intolerance is caused when the cells lining the small intestines do not have the enzyme acts. The lactose then ferments causing gasses that cause symptoms.
Symptoms: abdominal craps, bloating, and diarrhea
They break down sugars and such to their simplest forms
How do products like beans work
They are enzyme based dietary supplements that reduce gas in the digestive tract. Beano contains the enzyme alpha-galactosidase that breaks down oligosaccharides. Oligosaccharides can only be partially digested and are a major contribute to the fermentation of gas in the digestive tract.
What event is required but not sufficient to cause an infectious disease?
Adherence is the enhanced ability of microbes to attach to host tissues. It is required to initiate disease but is not sufficient because the host has many innate defenses that can thwart infection.
Describe the molecules or structures that facilitate pathogen adherence to host tissues?
Adhesions are glycoproteins or lipoproteins found on the pathogens surface that enable it to bind to a host cell
Capsules( form a thick coating outside the plasma membrane and cell wall and serves two important functions in bacterial pathogenicity
Fimbriae and Pili(are cell surface protein structures that functions in attachment)
Flagella( bacterial cell surface protein structure that functions in attachment
Why do certain pathogens only infect specific hosts?
Some pathogens only infect specific hosts because that host has the necessary molecules needed for the interaction of the host tissues and pathogen
At what body sites do pathogens typically attach and colonize?
pathogens typically attach and colonize at sites in the mucous membranes. Mucous membranes are found throughout the body, lining the urogenital, respiratory and gastrointestinal tracts. They secrete mucus which retains moisture and naturally inhibits microbial attachment.
Distinguish beween infection and disease?
Infection- situation in which a microorganism is established and growing in a host whether or not the host is harmed
Disease- an injury to a host organism caused by a pathogen or other factor that affects host function.
Which is a more serious condition, bacteremia, or septicemia, and why?
Septicemia is more serious than bacteria because bacteremia is the presence of bacteria in the blood where they do not grow and the immune system can take care of them. septicemia is when bacteria are present in the blood and ,multiply while they are there and the initial focus produces toxins or other poisonous substances. septicemia usually begins as an infection in a specific organ such as the intestines, kidneys, or lung and then spreads rapidly throughout the body from there.
symptoms include massive inflammation, culminating in septic shock(sepsis), and death
What are the virulence factors? How can the LD50 test be used to define virulence of a pathogen?
virulence factors are substances or strategies of a pathogen that indirectly or directly enhance invasiveness and host damage by facilitating and promoting infection.
The LD50(lethal dose 50) is a test designed to test the cells of a pathogen that kills 50% of the animals in a test group.Highly virulent pathogens show little difference in the number of cells required to kill 100% of the population as compared to 50% of the population.
What circumstances can contribute to attenuation of a pathogen?
Keeping pathogens in a lab culture=decreases virulence and attenuation is the decrease of loss of virulence
What major virulence factors are produced by Salmonella?
Type 1 fimbriae to facilitate attachment of cells to gastrointestinal tissues. several different classes of exotoxins. antiphagocytic proteins that block engulfment of bacterial cells by host phagocytes. proteins that promote survival if the bacterium does not get phagocytosis. siderophores organic molecules that bind iron tightly and in pathogenic bacteria, allows bacteria to outcompete host sequestration systems for iron. endotoxins
What is an opportunistic pathogen?What steps can a person take to help avoid opportunistic infections
Opportunistic infection is an organism that causes disease only in the absence of normal host resistance.
The steps a person can take to avoid opportunistic infections are not using intravenous drugs, no tobacco, or excessive alcohol
What is nosocomial infection
Infections that have been caught in a hospital and are potentially caused by organisms that are resistant to antibiotics
Identify host factors that limit or accelerate infection of a microorganism at selected local sites
accelerate infection- high virlulence of pathogen, lifestyle choices ( choosing to use drugs, smoke, or drink) and immunodeficiency disease (HIV)
limit infection- low virulence of pathogen and choosing not to drink, smoke, or use drugs
How do streptokinase and coagulase promote bacterial infection and invasion?
streptokinase- produced by streptococcus pyroxenes an dissolves fibrin lets allowing bacteria to spread by making the host produce plasmin
coagulase- produced by staphylococcus aureus and induces fibrin clotting which allows bacterial cells to remain at the site of infection ( prevents access to pathogens by cells of the immune response)
What is an IgAse and why would a bacterial pathogen produce one?
An enzyme that bacteria produce to counter that secretory antibodies isA which helps prevent pathogen adherence to host tissues. Once ida is countered by IgAse to hose defense is useless
Explain how diphtheria toxin work
diphtheria toxin- AB, inhibits protein synthesis in eukaryotic cells by allowing the B subunit of the toxin to bind with a specific host cell receptor protein. after binding, proteolytic cleavage between subunit B and subunit A allows subunit A to move across the host cytoplasmic membrane into the cytoplasm. Here subunit A disrupts protein synthesis by blocking transfer of an amino acid from tRNA to growing polypeptide chains. specifically inactivates elongation factor 2 (EF-2) a protein that functions in growth of polypeptide chains. by catalyzing the attachment of adenine diphosphate (ADP) ribose from NAD+. the activity of the modified EF-2 decreases dramatically and protein synthesis stops.
explain how botulism toxin work
neurological exotoxins (AB), the most potent biological substance known, the major one is protein that forms complexes with nontoxic botulism proteins to yield a bioactive protein complexes. the complex then binds tightly to presynaptic membranes on the termini of the stimulatory motor neurons at the neuromuscular junction, blocking the realize of acetylcholine. this prevents muscle contraction and is recognized as classic paralysis, which can leas to death by suffocation if the diaphragm muscles are severely affected. caused C. botulism growing and producing toxin in improperly preserves food. grows directly in the intestine sometimes.
explain how tetanus toxin works
on context with the nervous system, tetanus toxin is transported through the motor neurons to the spinal cord where it binds specifically to ganglioside lipids at the termini of the inhibitory intemeurons. this causes glycine(inhibitory neurotransmitter) release to stop and the motor neurons can't be inhibited resulting in the continual release of acetylcholine and uncontrolled contraction of the muscle fibers called spastic paralysis. if the mouth is involved it causes lockjaw and if the diaphragm is involved the prolonged contraction causes asphyxiation. grows deep in wounds that become anoxic such as punctres
explain how cholera toxin works
vibrio cholera, produces cholera enterotoxin(AB exotoxin) which when i tested, the organism tracts to the small intestine where the B subunit consisting of five identical monomers, binds specifically to GMI ganglioside, a complex glyolipid found in the cytoplasmic membrane of intestinal epithelial cells. the B subunit targets cholera toxin specifically to receptors in the intestinal epithelium but has no toxicity itself; toxicity is a function of the A subunit, which crosses the cytoplasmic membrane and activates adenylate cyclase, the enzyme that converts ATP to cAMP. the increase cAMP blocks NA+ uptake by small intestines epithelial call induces secretion of chloride and bicarbonate into the intestinal lumen. this change in ion concentration leads to the secretion of large amounts of water, the rate of water loss into the small intestine is greater than possible reabsorption of water by the large intestine, resulting in a large net fluid loss and watery diarrhea. if untreated, cholera victims can die within hours. however, if the lost fluids are replaced with an oral rehydration solution the cholera toxin can be neutralized and a cholera victim can return to normal in just a few days. acquired by ingestion of food or water contaminated with human feces.
Name some pathogens that produce exotoxins and what is their mode of action?
bacillis antracits(anthraz)- produces protective antigen (AB) which combines with other toxins to cause cell death
bordetella pertussis(whooping cough)- produces pertussis toxin(AB) which blocks G-proteins function and kills cells
clostridium perfringens(gas gangrene and food poisoning)- produces x, B, y , b toxins (AB) and enterotoxin (CT) which cases hemolysis, lecithin destruction, and alters intestinal permeability.
E. coli( gastroenteritis)- produces shiga-like (E. coli)(AB) which inhibits protein synthesis and induces bloody diarrhea.
pseudomonad aeruginosa(cystic fibrosis)-produces exotoxin A (AB) which inhibits eukaryote protein synthesis.
salmonella sp. (gastroenteritis)--produces enterotoxin (AB) and cytotoxin (CT) which lysis cells, inhibits protein synthesis and induces fluid loss from intestines
shigella dysenteriae(gastroenteritis)- produces shiga toxins (AB) which causes bloody diarrhea and hemolytic uremic syndrome
staphylococcus aureus (food poisoning)- produces x,B,y,b toxin(CT) toxic shock toxin (SA) and enterotoxins A-E (SA) which causes hemolysis, leukolysis, cell death, systems shock, vomiting, diarrhea
streptococcus pyogenes( strep throat and scarlet fever)- produces streptococcus O&S(CT) and erythrogere toxin (SA) which causes hemolysis and scarlet fever
Why do botulisms and tetanus show such apposing symptoms?
botulism toxin blocks the release of acetylcholine causing the muscles to stay relaxed. tetanus toxin blocks the release of glycine, which is an inhibitory neurotransmitter, causing acetylcholine to constantly be released enabling muscles to relax
How can activity of a hemolytic exotoxin be deteected
by streaking a pathogen on a blood agar plate(a rich medium containing 5% sterile blood)
What part of E. coli cell contains endotoxin? Why do gram positive bacteria not produce endotoxin?
the structural component LPS found in G-cells outer membrane. gram positive bacteria do not produce endotoxins because their cell wall doesn't have LPS, it is a thicker layer of peptidoglycan
Why is it necessary to test for endotoxin in water used for injectable drug preparations
so the person receiving the drug doesn't get injected with an endotoxin as well which can induce fear and trigger other, more serious symptoms
What major class of immune cells mediates an innate immune response. what additional type of immune cells is required for an adaptive immune response
phagocytes mediate innate immune response. cells of several types that can ingest, kill, and digest microbial pathogens. lymphocytes are additional tyra of immune cells needed for adaptive immunity
What terms is used to describe the unique molecules found on the surface of different pathogens
describe host tissues specificity for pathogens
most pathogens must adhere and infect at the site of exposure to imitate infection. however, the microorganism cannot colonize unless the host site isn't compatible with the pathogens nutritional and matabolic needs. different pathogens invade different tissues. some pathogens also interact exclusively with members of a few closely related host spaces because the host share tissues receptors. tetanus will to thrive in the intestines, just salmonella, sg=higella will not live in a puncture wound, HIV only infects humans and closest primate relatives because of HIV- binding cells surface proteins CXCRH (present on T-lymphocytes) and CCR5 (present on macrophages)
Identify physical and chemical barrier to pathogens. how might these berries be compromised
physical: tight junctions between epithelial cells in all body tissues that inhibit invasion and infection. mucosal surfaces have mucus that traps microorganisms, pollen, and other foreign agents. epithelial cells underlying mucous layers have cilia on their surfaces that expel pathogens
chemical: sebaceous glans on the skin secrete fatty acids and lactic lowering acidity of the skin to PH 5 which inhibits colonization of man pathogens. pathogens that are ingested are usually destroyed by stomach acids, but if they make it through they have to deal with the microbiota in the small and large intestines. defense's are produced in the skin, lungs, and gut which enhances resistance to infection and invasion. the lumen of the kidney, eye, respiratory system, and the cervical mucosa are constantly bathed with tears mucus or other secretions that contain lysozyme(enzyme that can kill bacteria y ingesting the cell wall). physical barriers can be compromised by thinning of the skin, atrophy of the vaginal wall, and loss of cilia in the respiratory tract. chemical barrier can be compromised by the atrophy of the glands that secrete mucus, tears, and other things
what other factors may control the outcomes of an infectious disease
antibiotic drug treatments nonspecifically killing harmless and even beneficial microbes in the body, smoking, poor diet, intravenous drug use, excessive alcohol consumption, and chronic lack of sleep can all play a role in the outcome of an infectious disease
describe the circulation of leukocyte from the blood to the lymph and back to the blood
leukocytes are formed by stem cells in bone marrow which then is released into blood circulation. once a leukocyte has traveled in the blood long enough to reach a capillary it passes to and from the blood into the lymphocyte system via lymphatic capillaries and then into the lymph nodes. the leukocyte travels in the lymphatic system until it is needed and is then released into the blood vie extravasation(diapedesis)
where do all blood cells originate? what determine what they differentiate into
all blood cells come from stem cells in bone marrow.
cytokines and chemokine are soluble proteins that influence many aspects of immune cell differentiation
what are examples of lymphoid tissue
mucosa- associated lymphoid tissue (MALT) is part of the lymphatic system that interacts with antigens and microorganisms that interact with the body through mucous membranes, including those of the gut, genitourinary tract, and brachial tissues.
although technically not part of the immune system, nonpathogenic normal microbiota plays a major role in preventing disease. describe this role
pathogens do not easily infect tissues that have a well established normal microbiota because the harmless microbes limit available nutrients and sites for infection by the pathogens
describe the process of phagocytosis. what types of cells are phagocytic
phagocytosis: phagocytes will engulf pathogens upon recognition of their pathogen- associated molecular patterns(PAMPSs) which are structurally repeating subunits common to broadly related groups of infectious agents, by their toll-like receptors(TLRs) which are one of a family of oattern recognition receptors(PRP) on phagocytes. once engulfed the pathogen will be pinched while enclosed a membrane bound vesicles called a phagosome. the phagosome will move into the cytoplasm and fuses with lysozyme to form a phagolyysozyme. the toxic chemicals and enzymes within the phagolysozyme combine to kill and digest and engulfed microbial cell.
the toxic compounds include: hydrogen peroxide, superoxide anions, hydroxyl radicals, singlet oxygen, hypochlorus acid, nitric oxide
describe several reasons why phagocytes are not always effective at removing pathogens from the body
phagocyte inhibition- some pathogens have mechanisms for neutralizing toxic phagocyte products, for killing the phagocyte or for avoiding phagocytosis. mycobacteria tuberculosis produces cerotenerds to neutralize singlet oxygen and has a waxy cell wall that absorbs free radicals. this pathogens lives and divides within the phagocytes. some pathogens such as streptococcus progenies produce leukocidins which kill white blood cells dead WBCs are found in pus. Lastly some pathogens contains a capsule which makes it difficult for the phagocyte to engulf them. host antibodies can contract this which is why pneumonias caused by streptococcus pneumonia. also produces M protein which alters surface pathogen and inhibits phagocytosis.
describe the inflammation reaction. what are some causes of inflammation.
the innate PRPs on macrophages and other tissue cells at the site of infection engage the pathogens PAMPs. this activates local cells at the site of infection mediators including cytokines and chemokine that interact with receptors on other cells such as neutrophils. the chemokines and cytokines mediators released by injured cells and phagocytes contribute to inflammation. these cytokines increase vascular permeability causing swelling(edema), reddening(erythema) and local heating associated with inflammation. the pressure associated with swelling also serves to force fluids away from blood vessels and into the lymphatic system, simultaneously helping to strengthen the immune response and prevent the spread of pathogen tot the bloodstream. the two main causes of inflammation are injury and infection. local tissues macrophages secrete a chemokine called CXCL8 which activates neutrophils to migrate along the chemokine gradient toward the source of CXCL8 where they begin to ingest and kill the pathogen. macrophages and other cells at the sight of infection produce pro inflammatory of cytokines including interleukin-1(L-1) IL-6 and tumor necrosis factor X( TNF-x)
identify the major symptoms of localized inflammation and of septic shock.
septic shock symptoms- body wide inflammatory event, massive flux of fluids central vascular tissue causing a loss of systemic blood pressure and the influx of fluid from vascular tissue into extravascular space.localized inflammation
what is opsonization and how does opsonization help fight bacterial infections
the coating of pathogens with antimicrobial host proteins, such as antibodies or C3b, resulting in enhanced phagocytosis of the target cells. neutralizes pathogens and makes them much more likely to be identified, engulfed, and destroyed by phagocytes. this is because moth pathogens including neutrophils and macrophages have anybody receptors (fcR) and C3b receptors (C3R) on their surface which bind antibody and C3b complement protein, respectively
what are complement and the complement pathway
complement system is a set of circulating, inactive proteins that are sequentially activated in response to a pathogen. the classical pathway of complement activation is initiated when the complement binds to antibodies that are attached to a pathogen.C1 cleaves C2 and C4 to form C2a-C4b otherwise known as C3 converts. this converts breaks C3 to C3b which binds to the target cell and C3a which diffuses into the surrounding area and serves as a chemoattractant. with C3b added, the C3 converts also binds C5 leading to C5a being released with C5b binding to the cell. This is called membrane attack complex (MAC)
identify and compare the targets and the recognition mechanisms used by T-cytotoxic cells and NK cells
targets of natural killer cells; intracellular pathogens(viruses), cancer cells, recognition mechanisms. recognize and destroy pathogen-infected or tumor cells by using a two receptor system. the molecular targets of NK cells are MHCI receptors on their surfaces t recognize MHIC proteins on normal, healthy cells. binding of the MHIC recognition receptors on NK cells to MHIC on other cells deactivates the NK cell, turning off the perforin and granzyme killing mechanisms. in addition to a deficiency of MHIC proteins, pathogens-infected or tumor cells frequently express stress proteins on their surfaces NK cells have complementary receptors for many of these stress proteins. especially in the absence of the MHIc interactions, the stress receptors on NK cells engage stress proteins on the target cells.
targets of cytotoxic T-cell;infected cells. i the cells that have been infected by viruses or other intracellular pathogens, MHIC proteins display peptides derives from the infectious agent, signaling a T-cytotoxic cell. granzyme( an enzyme that induces programs cell death (apoptosis), perforin(chemically and functionally similar to C9, it pokes holes in (perforates)the target membrane, and T-cells(originate in bone marrow, but nature in the thymus
under what conditions are interferons produced and how do they limit the transmission of viruses from one host cell to another
interferons are small cytokine proteins that are produced by virally infected cells. serve as a warning system and prevent viral replication by stimulation the production of antiviral proteins in uninfected cells once they receive the interferon signal from infected cells
Distinguish between immune specificity, memory, and tolerance.
specificity: antibody reaction is dependent on lymphocyte cell receptors interacting with individual pathogen. immune cells have surface receptors that interact with individual antigens
memory:subsequent exposures to the same antigen result in rapid production of large quantities of antigen-reactive T cells or antibodies. the first antigen exposure induces multiplications of antigen-reactive cells, resulting in multiple copies or colonies. after a subsequent exposure to the same antigen, the immune response is faster and stringer due to the large number of responding cells. immune responses as a results of immune memory, antigen preexposure triggers a much stronger secondary response.
tolerance: the acquired inability to make an adaptive immune response to ones own antigens. discrimination between foreign and host antigens. failure to develop tolerance may result in reactions against self called autoimmunity.
Distinguish between clonal deletion and clonal selection
T cell selection and tolerance: procures T cells travel from the bone marrow to the thymus where they mature and are out under both positive and negative selective pressure.
positive selection-t cells that recognize MHC peptides are retained
negative selection- t cells that pass the positive selection and strongly bind to self-antigens are selected against
clonal deletions-more than 99% of t cells that enter the thymus do not survive the selection process. remaining t cells react strongly with foreign antigens
B cell selection and tolerance:the body produces thousands of different B cells, each able to react to different antigens. positive b cell selection occurs when the b cell receptor encounter an antigen that they recognize. upon recognition the b cells; 1. proliferate(make more copies) 2. differentiate(into memory cells and plasma cells) 3. produce proteins(antibodies). negative b cell selection occurs in the bone marrow where self-reactive b cells are deleted(clonal deletion) or silenced(clonal anergy) because they lack a T cell help signal.
Where does the antibody bind to an antigen? What part of the antibody binds?
antibodies so not interact with an entire antigen but only with a distinct portion of the molecule called an antigenic determinant or episode. may include sugars, amino acids, and other organic molecules. because antigens need to be associated with MHC to be recognized by T cell receptors only short peptide sequences by T cell receptors, only short peptide sequences are recognized by TCRs. antibodies are specific for the antigen it was made against. variable region of antibody binds to the epitope or the antigenic determinate of the antigen. then complement binds. then cell lysis
Give an example for each: natural and artificial active immunity and natural and artificial passive immunity.
The immune response may be active, which is generated from exposure to an antigen or passive, which is the transfer of antibodies or immune cells. active immunity develops memory cells therefore producing a long-lasting immunity. passive immunity consists of pre-forming antibodies or cells and has a rapid effect but doesn't confer lasting immunity. antibody is given to you, antibodies in breastmilk, anti-venoms.
The natural immunity occurs without direct medical intervention while artificial immunity requires injections or infusions.
natural active immunity- getting a disease and recovering
natural passive immunity- passing antibodies to nursing infants through breast milk
artificial active immunity- receiving a vaccination shot and developing immunity
artificial passive immunity-receiving pre-formed antibodies(antiserum)
What are the different classes of antibody and where are they found? what is unique about each?
Five major classes: igG, igA,ig M, igD, igE
igG- the most common antibody circulation the body. four polypeptide chains (two navy and two light). antigen-binding site results from interaction between heavy and light chains. billions of different antigen binding sites
igM-usually an aggregate of five immunoglobulin molecules attracted by at ease one j(joining) chain
dimers of igA- presented in body fluids such as saliva, tears, breast milk, colostrum, and mucosal secretions
igE- found in serum and functions as an antibody that binds to eosinophils
igD-present in serum and has no known function
Describe primary and secondary antibody responses in serum
primary exposure time 0- initial antigen contact at day 0 initiates a primary immune response. after several days igM antibody produced at detectable but low titers. in the absence of antigen the titer decreases with time
secondary exposure time 11- another contact with the same antigen at day 100 initiates the secondary immune response. antibody class switches rapidly to gig, now produced in high titers. in the absence, the titer again decreases with time
Describe the basic structure of an antibody
antibodies or immunoglobins are either soluble proteins or cell surface antigen receptors on B cells. can bind to toxins or viruses to neutralize them. can bind to foreign cells and make them easier to engulf by phagocytes. the heavy chains of a given antibody define its class based on amino acids sequence. all five classes have different structural characteristics, expression patterns, and functional roles.
Identify the cells that display MHC class 1 and MHC class 11 proteins on their surfaces.
majorhistocompatibility complex molecules are also called human leukocyte antigens in humans.
MHC1 are found on all nucleated cells. present internal antigen to CD*+T cells. cytoplasmic antigen can originate from viral proteins or cancer proteins. the cell is then targeted for destruction but T cells. MHC 1 class proteins are the major antigen barriers for tissue transplantation. found on all tissues and have many different forms in a population, they are the basis for tissue rejection
MHC class 11 are found on professional antigen-presenting cells, such as dendritic cells, macrophages, and B cells. present the internalized antigen to CD4+ T cells. activate helper T cells. receive T cells help.
How are T cell similar and different
T-cytotoxic cells are cells that directly kill cells that display surface foreign antigens. contact between Tc cells and target cell is required for cell death. on contact, granules in T cell migrate to contact site. degranulation occurs and causes pores(perforin) in target cell membrane. also contain granzymes that cause apoptosis.
different classes of T helper cells. Th1 subset activates macrophages. secrete cytokines(including gamma interferon and others). activated macrophages kill intracellular bacteria. also play a role in inflammation and rejection of transplanted organs. Th2 subset plays a crucial role in B cell activation and antibody production.
antigen presentation by dendritic cells play a role in the development of Th17 cells. dendritic cells encounter pathogen. dendritic cells present antigen and secrete cytokines. the cells become Th17. Th17 cells recruit neutrophils
dendritic cell that do not interact with a pathogen . the cells become Treg cells. Treg cells suppress immunity and inflammation
Compare and contrast the four types of hypersensitive. which ones are mediated by antibody?
hypersensitivity- inappropriate immune response that result in host damage. hypersensitivity diseases are categorized according to antigens and effector mechanisms that produce disease.types 1,2,3 are mediated by antibodies
type 1- immediate, mediated by igE sensitization of mast cells, happens in minutes. ex bee sting or hay fever
type 2- cytotoxin, igG interactions with cell surfaces antigen , happen in hours. ex drug reaction(penicillin)
type 3- immune complex, antigen binds to antibody, igG interactions with soluble or circulating antigen, happen in hours. ex systemic lupus erythermatosus
type 4- delayed type, mediated by Th1 imflammatory cell activation od macrophages, can take hour-days. ex poison ivy Tb test
What is autoimmunity and give examples of autoimmune diseases. explain the mechanism associated with each disease.
autoimmune disease-occurs when T and B cells are activated to produce immune reactions against self proteins. result in host tissue damage. some diseases are caused by autoantibodies(antibodies that interact with self antigens). type 1 diabetes affects the pancreas-mechanism: cell-mediated and autoantibodies against surface and cytoplasmic antigens of be a cells pf pancreatic islets(11 and 1V). male infertility, affects sperm cells-mechanism: autoantibodies prevent absorption of vitamin b12(111)
How do super antigens cause disease?
proteins capable to elicit a strong response because they activate more T cells than a normal immune response. Produced by many viruses and bacteria that interact with T cells receptors. super antigen-activated T cells may produce systemic disease characterized by systemic inflammatory reactions. ex stapococcus orris.
What causes immunodeficiency and what is the result of this condition?
activate immunity is critical for infectious disease resistance. animals (humans included) with decencies in B cells are prone to bacterial infections while those with T cell deficiencies are prone to viral infections and cancers.
severe combined immune deficiency syndrome is a serious, congenital deficiency of both B and T cells. patients live a restricted life, limiting their exposure to pathogens
acquired immunodeficiency syndrome is caused by HIV infection that progresses and kills CD4+T cells. patients are prone to opportunistic infections and cancer since they are deficient in T cell help
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