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immunity
Fichas del conjunto (110)
- 1what are pathogens?microorganisms which cause infectious diseases, such as; bacteria, fungi, viruses
- 2what is a disease?physical/mental symptoms caused by a pathogen
- 3what requirements do microorganism need to have to be classed as a pathogen?-gain entry to the host
-colonise the tissue of the host
-resist the defense of the host
-cause damage to hosts tissues - 4what happens if a pathogen gets into the host and colonises its tissue?causes an infection
- 5how can an infection lead to a disease?when an infection leads to recognise symptoms in the host
- 6what is transmission?when a pathogen is transferred from one individual to another
- 7humans three lines of defence?-non specific barriers
-non specific immune system
-specific immune system - 8what is a non specific barrier?the skin and associated chemicals to stop microbes entering the body
- 9what is a non specific immune system?the phagocytes that quickly destroy microbes that pass the first line of defence
- 10what is a specific immune system?the lymphocytes that kill any microbes that pass the second defence and remain on guard for future attacks
- 11how does the skin prevent microbes entering the body?-has a tough, impenetrable barrier (epidermis)
-thick
-epidermis cells toughened with keratin - 12how does saliva/tears/sweat prevent microbes entering the body?-contain lysozyme enzymes
-these enzymes destroy bacteria growing on skin surface by digesting their peptidoglycan cell walls - 13how does the respiratory tract prevent microbes entering the body?-protected by sticky mucus secreted by goblet cells
-goblet cells trap pathogens and other particles in inhaled air before they can reach the delicate alveoli
-mucus contains lysozymes
-cilia constantly sweep the mucus upwards to the throat where it is swallowed so the pathogens are killed by stomach acid - 14how does the digestive tract prevent microbes entering the body?-protected by a concentrated acid in stomach
-acid denatures pathogenic enzymes - 152 ways microbes enter the body?-gas exchange system
-digestive system (food/water via mouth) - 16how does mucus prevent microbes entering the body?covers exchange surfaces and forms a thick sticky barrier that is difficult to penetrate
- 17how do pathogens cause diseases?-by damaging hosts tissue
-producing toxins - 18how do the pathogens damaging the hosts tissue causes diseases?-prevents tissues functioning properly
-inhibit synthesis of DNA, RNA and proteins by the hosts cells
-break down membrane of hosts cells - 19what is friendly bacteria?-bacteria that colonise the skin, mouth, lower digestive tract, respiratory tract and vagina
-prevent infections by out competing pathogens for food and space - 20where are leukocytes derived from?stem cells, produced in the bone marrow
- 21what happens to the stem cells in bone marrow?-they differentiate into different kinds of leukocytes
- 22different types of leukocytes?-phagocytes
-granulocytes
-T lymphocytes
-B lymphocytes - 23what are phagocytes for?for phagocytosis
- 24what is granulocytes for?inflammation
- 25what are T lymphocytes for?cell-mediated immunity
- 26what are B lymphocytes for?antibody mediated immunity
- 27what happens after WBC (white blood cells) are produced?-transported to different parts of the body via the blood
-final destination is the lymphatic system - 28what is the lymphatic system made up of?a series of 2 blind-ending tubes called 'lymph ducts' or 'lymph vessels', which drain tissue fluid back into blood stream
- 29where are pathogens found in the body specifically?-tissue fluid
- 30where do WBC carry out pathogen destruction?-lymphatic system
-WBC collect and destroy pathogens at lymph nodes and spleen
-tissue fluid (containing pathogens) is drained - 31What is the second line of defence?(non-specific immune system)
-phagocytes
-granulocytes - 32structure of phagocytes?-large
-irregularly shaped - 33what do phagocytes do?-remove cell debris/dust particles
-remove pathogens - 34how do phagocytes remove debris/pathogens from the body?-surround and ingest pathogen by phagocytosis to form a vesicle
-vesicle fuses with lysosomes (contain hydrolytic enzymes)
-these enzymes are released into the phagosome
-then digests the microbe - 35where are granlocytes found?connective tissue throughout the body
- 36what is inflammation?when granulocytes cause a localised response to an injury or infection
- 37what chemical do granulocytes release?a chemical e.g. histamine
- 38what does the chemical released by granulocytes do?stimulates;
-vasodilation (increase blood flow to the area-turns area red)
-capillary leakage (so phagocytes can enter local tissue fluid-area swells)
-blood clotting (seal wound-scab forms) - 39what is in puss?dead pathogens and phagocytes in excess tissue fluid
- 40What is a fever?-histamine and bacterial toxins cause an increase in the body's temperature from 37 C up to 39 C
-helps immune system
-inhibits growth of some bacteria - 41what is the third line of defence?specific immune system
- 42what forms the specific immune system? And what is it's role?-lymphocytes form the specific immune system
-kills invading pathogens
-remembers pathogens features so that future infections can be prevented
-recognises specific foreign cells by antigens - 43what type of animals is the only type to have a specific immune system?vertebrates
- 44What are antigens?-large protein molecule on outer surface of a cell
-cells from different individuals have different antigens, all cells from one individual have same antigens
-genetically controlled (close relatives have more similar antigens) - 45what are 'self'antigens which the immune system recognises as its own
- 46what are 'non-self'?antigens the immune system recognises as foreign
- 47what are antibodies?-protein molecule that binds specifically to an antigen
- 48structure of antibodies?-4 polypeptide chains (2 heavy 2 light)
-joined by strong disulphide bonds
-Y shape structure
-stem=constant region
-ends of arms=variable regions - 49what is the stem of the antibody?-constant region
-same amino acid sequence/structure in all antibodies - 50ends of the arms of antibody?-variable regions
-different antibody molecules have different amino acid sequence/structures
-where antigens bind to form a highly specific antigen-antibody complex - 51What do B lymphocytes do? what are they triggered by?-make antibodies
-cause antibody-mediated response
-triggered by non-self antigens on surface of pathogens/toxins they produce - 52what do B Lymphocytes become?-become either plasma cells/
-secreting antibodies/
-memory cells for future invasions by same pathogens - 53where are B and T cells made and where do they mature?-both cells made in bone marrow
-B= matures in bone marrow
-T= matures in thymus gland - 54where are antibodies attached to the B cell?by the outside of their cell membrane-behave like receptors
- 55What happens when an antigen binds to their receptors?-an antigen-antibody complex forms
-B cell clones its self
-millions of specific antibodies secreted into body - 56role of T cells?-kill infected cells
-help other parts of immune response to work more efficiently
-triggered by infected/cancerous cells
-cause cell-mediated response
-form antigen-receptor complexes - 57what do T cells become after triggered by cancerous/infected body cells?T killer cells/T helper cells/T memory cells
- 58T cells receptors compared to B cell receptors?-similar
-do not secrete antibodies - 59how do T cells recognise infected cells?-infected cells place pathogens antigens on their surface (forms antigen-presenting cells)
-process is self destructing but also prevents virus inside it from 'lysing' the cell and releasing hundreds of viruses - 60what happens as soon as a match is found between a B or T cells and its matching receptor molecule?-the binding of the antigen to the receptor stimulates the lymphocyte to divide repeatedly by mitosis
-creates army of identical clones B or T cells - 61what is clonal selection?the army of identical clones B or T cells created by the lymphocyte dividing (selection of cloning)
- 62cell mediated immunity (cytotoxic/killer T cells)?-killer T cells bind to antigens on surface of infected cells
-they kill cells by releasing proteins which insert into the cell membrane of the other cell
-creates pore which causes the cell to burst - 63cell mediated immunity (helper T cells)?-bind to antigens presented on infected cells
-secrete chemicals called cytokines
-this stimulates all the other white blood cells and speeds up immune responses - 64what does AIDS/HIV do to helper T cells?-destroys t helper cells
-so immune system doesn't work nearly as well without them - 65cell mediated immunity (memory T cells)?-remain in blood for decades after infection
-so same antigen will be identified quickly in a subsequent infection
-and T cells will quickly divide to form killer T cells and helper T cells - 66antibody-mediated immunity (plasma cells)?-secrete soluble antibodies that are carried around the blood, lymph and tissue fluid
-soluble antibodies bind to any antigens they come into contact with=antibody-antigen complexes - 67why is it highly likely that every antigen will be targeted by an antigen?because a huge amount of antibodies are produced in the body
-high amount of rough ER for synthesising and transporting antibodies out the cells - 68Various ways antibodies help kill cells?-by binding to antigens on pathogens
-binding to free toxin proteins
-linking antigens together into large clumps - 69how do antibodies binding to antigens on pathogens help kill cells?prevents them from attaching to and infecting cells
- 70how do antibodies binding to free toxin proteins help kill cells?prevents them causing a disease
- 71how do antibodies help kill cells by linking antigens together into large clumps?-each antibody molecule has two antigen binding sites (one on each arm of the Y)-This allows antibodies to stick antigens together= "agglutination"
-allows pathogens or infected cells to be easily destroyed by phagocytes or killer T cells - 72cell mediated immunity (memory B-cells)?-continue to secrete antibodies in small quantities for decades
-can multiply rapidly to produce an instant supply of plasma cells if the same pathogen invades again - 73primary immune response ?-the slow and weak response to a new infection
-during this period the symptoms are shown due to; toxins and cell death due to the pathogen + immune response itself - 74what is phagocytosis?when large particles are too big to cross membrane so need to be engulfed by phagocytes in the form of vesicles formed from the cell surface membrane
- 75why does it take several days for clonal selection to take place when a new antigen is encountered?-there's only a few lymphocyte cells of each kind for the antigen to encounter
-clone army tends to be small - 76What is the secondary immune response?-memory cells (T&B) remain in blood
-so after an infection by the same antigen, the clonal selection stage occurs much faster and greater number of antibodies are produced
-pathogen is destroyed before it reproduces enough to cause a disease - 77why does the secondary immune response not work with the common cold and flu?-the pathogens have constantly changing antigens (antigenic variability)
-causes a new primary response, with all the symptoms of the accompanying disease - 78what is antigenic variability ?when the pathogens antigens are constantly changing
- 79what is active immunity?becoming immune through acquiring a disease
- 80what is artificial immunity?-injecting people with an antigen that will promote the primary immune response
-but modified so that it's non-virulent (won't cause the disease)
-immune system makes memory cells so if a person is infected with the real virulent pathogen, the more effective secondary immune response is triggered and the pathogen is killed before it causes the disease - 81what do vaccinations provide to a number of potentially fatal diseases?artificial immunity
- 82what do people normally get vaccinated against?diphtheria, tetanus, whooping cough, polio, measles ,mumps, rubella, and TB
- 83what ad why is a booster given?causes the body to make more memory cells
- 84what is passive immunity?-produced by introduction of antibodies into individuals from an outside source
-antibodies not produced by individual and are not replaced when they're broken down by the body, so the immunity is short-lived - 85what is passive immunity used for?-rabies
-tetanus
-measles
-hepatitis B - 86example of passive immunity occurring naturally?-when mother passes antibodies to her child
-across placenta to fetus
-passed through milk
-babies digestive system doesn't function at this stage the antibody proteins can be absorbed intact
-helps baby survive in world full of pathogens - 87why isn't passive immunity long lasting?person doesn't have memory cells so the antibodies eventually will be digested and the person can't make more
- 88what are monoclonal antibodies?isolating a single type of antibody and cloning it
- 89how monoclonal antibodies are made?1)inject mouse with the antigen that you need antibodies for
2)after few days mouse is killed and B cells extracted from spleen
3)B cells grown in culture flask, where they multiply by mitosis, making millions of identical cloned cells each secreting identical antibodies (monoclonal antibodies) - 90two problems with extracting B cells from mouse's spleen?-B cells won't grow in test tubes
-the spleen extract contains a mixture of thousands of different B cells each with specific antibodies - 91How to solve the problem of B cells not being able to be grown in test tubes?-using immortal cancerous mouse cells (divide indefinitely in vitro)
-mixed within myeloma cells that divide readily outside the body (tumour) in a petri dish and fused with a detergent
-fused cells= hybridoma cells (have properties of both cell types being able to grow in vitro and produce antibodies) - 92How to solve the problem of the spleen extract containing a mixture of many B cells each making their own specific antibodies?-diluting cells into hundreds of wells in an immunoassay plate (one cell per well)
-cells multiply in wells and secrete a different clone of antibodies in each well
-each well is screened for production of the required antibody - 93How are the fused cells (in production of monoclonal antibodies) separated?-under microscope
-each cell is cultured to form a group
-each group is tested to see whether it id producing the required antibody - 94uses of monoclonal antibodies?-can be made to an antibodies can be made to an antigen found on a specific cancer cell
-detects presence of hCG in urine in a pregnancy test strip
-in passive immunity to help the body's normal immune response to a serious infectioj - 95How can monoclonal antibodies be used to target cancer cells?-antibodies can be made to an antigen found on specific cancer cell
-a toxic agent is bound to the antibody
-antibody toxin complex is injected into a cancer patient + the antibody will ensure the agent is carried only to cancer cells and nowhere else - 96how are monoclonal antibodies used in pregnancy tests?antibodies of the hormone hCG, produced in pregnancy are bound to a test strip to detect the presence of hCG in urine
- 97stage 1 of HIV?-Acute
-3-12 weeks
-flu like symptoms
-HIV antibodies found in blood
-loss of T helper cells
-infected T helpers are killed by T killers (reduces rate of virus replication but doesn't stop it) - 98Stage 2 of HIV?-Chronic stage
-symptoms disappear
-T killer cells kill off infected CD4 T helper cells
-lasts many years in healthy people
-susceptibility to diseases increase gradually
-reactivation of dormant diseases like shingles and TB - 99stage 3 of HIV?-disease stage
-viral load becomes so great
-T helper level falls to below half a normal level - 100Stage 4 of HIV?-advanced
-low, badly damaged immune system
-opportunistic infections-TB, meningitis, pneumonia
-When the number of your CD4 cells falls below 200 cells/mm3= AIDS
-if you develop one or more opportunistic infections=AIDS - 101What is HIV?-human immuno deficiency virus
-weekends immune system
-retro virus
-caused by humans eating orangutans
-leads to AIDS (acquired immuno deficiency virus)
-attacks T cells/cD4 cells and uses them to make copies of itself - 102how is HIV transmitted?-sexual contact
-enters blood stream via mucous membranes lining the vagina, rectum and mouth
-Macrophages and dendritic cells on the surface of mucous membranes bind virus and shuttle it into the lymph nodes
-which contain high concentrations of helper T cells (CD4+ T cells) - 103What happens after HIV binds to cell membrane/T helper cell receptors?-virus' genetic material inserted into cell
-reverse transcription inserts DNA into human genome
-cell produces HIV
-immune system initiates anti-HIV antibody and cytotoxic T cell production (can take 1-6 months) - 104What does the loss of T helper cells mean?-macrophages won't be activated
-B cells won't be activated
-T killer cells won't be activated - 105How does HIV make copies of itself?-HIV attaches to CD4/T helper cell by the glycoproteins on surface of HIV
-releases contents into CD4/T helper
-Once inside the cell, HIV changes its genetic material (HIV RNA) into HIV DNA via the enzyme reverse transcriptase - 106reverse transcription of HIV?-HIV DNA then makes long strands of mRNA proteins, and transports them towards the edge of the cell
-This is then used for producing more HIV - 107what gases do we exchange?-oxygen
-carbon dioxide
-water
-glucose - 108what is agglutination?-sticks pathogens together
-prevents pathogens working
-makes it easier for it to engulf - 109what is antigen presentation-warns body a pathogen is present
-white blood cell infects itself with pathogen to warn body - 110—
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- - biology Fichas sobre immunity, creado por hanna akhrass el 22/01/2016.
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- hanna akhrass
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