11828382
Description
Flashcards by Charlotte Willis, updated more than 1 year ago
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Created by Charlotte Willis
almost 7 years ago
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| Question | Answer |
| What is a Pathogen? | A disease causing micro-organism -e.g Bacteria, Virus, Fungi |
| What is the Body's defence against pathogens? | - Barriers (prevents pathogens entering the body) -Phagocytes (perform phagocytosis and stimulate specific response) -Specific Response (uses lymphocytes to produce memory cells and antibodies |
| What are the Barriers? | Skin, Cilia and Mucus in Lungs, Hydrochloric Acid in Stomach |
| Process of Phagocytosis? | - pathogen releases chemicals - this attracts the phagocyte - the phagocyte binds to the pathogen - the phagocyte engulfs the pathogen forms a phagosome around the pathogen - lysosomes inside the phagocyte release digestive enzymes into the phagosome breaking down the pathogen by hydrolysis |
| Describe the Specific Immune Response | - phagocytes perform phagocytosis (engulf and destroy pathogen) without destroying the antigen, they place antigens on their surface, they present antigens - t lymphocytes (t cells) bind to the antigen and become stimulated - they divide by mitosis to form 3 types of cells: t helper, t killer, t memory - t helper cells stimulate b lymphocytes (b cells) - t killer cells destroy infected cells (infected by virus) -t memory cells provide long term immunity - b lymphocytes (b cells) engulf and present antigens on their surface, the t helper cells bind to this - the b cells become stimulated and divide by mitosis to make 2 types of cells: Plasma Cells & B Memory Cells -Plasma cells make antibodies -B memory cells provide long term immunity |
| What is an Antigen? | A protein on the surface of a pathogen that stimulates an immune response |
| How does the immune response leas to production of antibodies? | Phagocytes stimulate the t cells, the t cells form t helper cells, the t helper cells stimulates the b cells, the b cells form plasma cells, the plasma cells make antibodies |
| What is an Antibody? | - A Globular Protein -made by Plasma Cells -3 Regions, Variable, hinge, constant -2 heavy chains and 2 light chains |
| How do Memory cells (B/T) work? | -made during the specific immune response after a new infection by a pathogen (called a primary infection) -B and T memory cells remain in the blood -if person is reinfected by the same pathogen (called a secondary infection) the memory cells will recognise the pathogen and produce antibodies RAPIDLY and to a LARGE amount -therefore the pathogen is killed before it can cause harm = immunity |
| How does a vaccine produce immunity? | involves giving an injection that contains dead/weakened pathogens that carry antigens which stimulates the immune response leading to production of antibodies & memory cells |
| Active VS Passive Immunity | Active = individual has memory cells - can make their own antibodies + provide long term immunity Passive = person given antibodies, these work then die, no long term immunity, no memory cells |
| How does active immunity occur | Naturally - by primary infection Artificially - Vaccination |
| How does passive immunity occur? | Naturally = from mother to baby Artificially = injection |
| Successful vaccination Programme? | produce suitable vaccine (effective – make memory cells, does not cause disease, no major side effects, low cost, easily produced/transported/stored/administered) herd immunity |
| What is Herd immunity? | when a large proportion of the population is vaccinated, therefore most people will be immune, only a few will not be a immune, increases chance of non-immune person coming into contact with immune person, so the pathogen has no where to go, so it dies out |
| Problems with Vaccination Programmes | - vaccine does not work (dead form ineffective, pathogen hides from immune system) - vaccine not safe (no weak/inactive form, causes major side effects) - many strains of pathogen - cannot achieve herd immunity (logistic of vaccinating large proportion) - antigenic variability |
| What is Antigen variability? | the pathogen mutates, the antigen changes shape, so the memory cells no longer complementary – do not recognise the pathogen, therefore the pathogen can re-harm |
| What is a monoclonal antibody? | one type of antibody, complementary to one type of antigen, made by one type of plasma cell |
| What are monoclonal antibodies used for? | Identify specific antigens or antibodies in person's blood, or pregnancy |
| How do monoclonal antibes identify specific antigens in the blood? | e.g. identify PSA antigen made by prostate cancer place monoclonal antibodies complementary to PSA antigen on test plate add person's blood to test plate if PSA antigen is present in the blood, it will bind to the monoclonal antibodies then a 2nd set of monoclonal antibodies with an enzyme attached is added if the PSA antigen is present, this 2nd set will bind to it if the PSA antigen is not present, this 2nd set will not bind the test plate is then washed if PSA antigen is present, 2nd set of monoclonal antibodies will attach, this will not be washed away, so the enzyme will be present if PSA antigen not present, 2nd set of monoclonal antibodies will not attach, this will be washed away, so enzyme also washed away a colourless substrate is then added, if the enzyme is present it will breakdown the substrate causing a colour change, if the enzyme is not present there will be no colour change therefore: colour change occurs = enzyme present/PSA antigen is present, no colour change = no enzyme present/no PSA antigen is present |
| How do monoclonal antibodies identify specific antibodies in the blood? | e.g. identify TB antibodies in the blood place antigen complementary to TB antibodies on test plate add person's blood to test plate if TB antibodies are present in blood, they will bind to the antigen then a set of monoclonal antibodies (with an enzyme attached) complementary to the TB antibodies are added if the TB antibodies are present, the monoclonal antibodies will attach if the TB antibodies are not present, the monoclonal antibodies will not attach the test plate is then washed if the TB antibodies are present, the monoclonal antibodies will attach, this will not be washed away, so the enzyme will be present if the TB antibodies are not present, the monoclonal antibodies will not attach, this will be washed away, so the enzyme will be washed away a colourless substrate is then added, if the enzyme is present it will breakdown the substrate causing a colour change, if the enzyme is not present there will be no colour change therefore: colour change occurs = enzyme present/TB antibody is present, no colour change = no enzyme present/no TB antibody is present |
| How are monoclonal antibodies used in pregnancy testing? | Pregnant Women produce HCG Hormone in their Urine Test Strip has 3 parts to it (1st: start contains antibodies complementary to HCG, 2nd: middle contains antibodies complementary to HCG-Antibody complex, 3rd: end contains antibodies complementary to HCG Antibodies) if woman is pregnant, HCG in the urine binds to antibodies on 1st part forming a HCG-Antibody complex, the HCG-Antibody complex then binds to antibodies on the 2nd part forming a blue line (positive result), HCG Antibodies also bind to 3rd part as a control if woman is not pregnant, no HCG in urine so nothing binds to HCG Antibodies in 1st part, so nothing binds to antibodies in 2nd part leaving no blue line (negative result), the HCG Antibodies still bind to 3rd part for the control |
| What is HIV/AIDs? | HIV = Human Immunodeficiency Virus AIDs = Acquired Immunodeficiency Syndrome HIV is the Pathogen, AIDs is the Infectious Disease HIV is spread by fluid to fluid contact (unprotected sexual intercourse, sharing needles, mother to child via placenta or breast feeding) HIV damages and destroys T Helper Cells, therefore person no longer produces Immune Response and has no defence to against pathogens/infections = AIDs With AIDs, individual at risk from all sorts of pathogens/infections called Opportunistic |
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