Flashcards
Immunity
Flashcards do conjunto (42)
- 1DiseaseAn interaction between pathogen and body's various defence mechanisms
- 2Pathogenmicro-organism that cause disease
- 3Vaccinecontains antigens of the pathogen which stimulate production of antibodies
- 4Non-specific mechanism- Respond to all the pathogens
* barrier to entry of pathogens
* phagocytosis - 5SpecificDistinguish between different pathogens but its less rapid and provide long lasting immunity
* cell mediated
* Humoral - 6What cause time lag between exposure to pathogen and body's defence?When an infection occurs, there is a lymphocyte that is already complementary to the antigen but needs to be stimulated to a number where it is effective at destroying it
- 7Describe how B-lymphocytes respond when they are stimulated by antigens.divide by mitosis / form clones;
produce plasma cells;
(plasma cells) make antibodies;
(plasma cells) produce memory cells; - 8What is an antigen?part of molecule that stimulates immune response
- 9What is an antibody?Protein specific to antigen
- 10Types of WBCPhagocytes: ingest and destroy pathogen by phagocytosis
Lymphocytes: involved in immunity - 11Barriers to entry i) skin ii) lungs iv) eyes - Stomachi) keratin as barrier
ii) mucus traps micro-organisms
iv) tears contain lysosomes/enzymes which destroy microbes
* Hydrochloric acid which provides a low pH so enzymes of most pathogen are denatured - 12When a pathogen enters the body it may be destroyed by phagocytosis. Describe how. (4)1. Phagocyte is attracted to the pathogen by chemoattractants and moves along a concentration gradient
2. Phagocyte binds to the pathogen and engulf to form a vesicle known as phagosome
3. lysosomes within the phagocyte move towards the phagosome by engulfing the bacterium
3. Lysosomes release their lytic enzymes where they break down the bacterium
4. The breakdown products of the bacterium are absorbed by the phagocyte - 13What is immunityIt is the ability of an organism to resist infection by protecting against disease-causing micro-organisms that invade their body
- 14Antigens are...proteins that are part of the cell surface membrane or cell walls of invading cell
- 15B-Lymphocytes : Humoral Immunity (involves antibodies)- Matures in bone marrow
- Produces antibodies
- responds to foreign material outside body cells
- responds to bacteria and viruses - 16T-Lymphocytes: Cell mediated immunity (body cells)- Matures in thymus gland
- responds to foreign material inside body cells
- Responds to own body cells altered by viruses, cancer to transplanted tissues - 17How does T-lymphocytes distinguish between invader cell and normal cell?- Phagocytes that have engulfed and broken down a pathogen will present pathogens antigens on their surface
- body cells invaded by a virus will present viral antigens
- cancer cells will present antigens too - 18ANTIGEN PRESENTING CELLS* PHAGOCYTES
* BODY CELL
* CANCER CELL - 19Stages in response of a T lymphocytes1. Pathogens invade body cells and are taken in by phagocyte
2. Phagocyte presents antigens from pathogen on its cell surface membrane
3. Receptors on T helper cells fits this antigen
4. This activate other T cells to divide by mitosis to form a clone - 20Cloned T cells will form- memory cells : provide rapid response to future infections
- stimulate phagocytes to engulf pathogens by phagocytosis
- stimulate B cells to divide
- kill infected cells - 21How T-cells kill infected cells?They make a protein which makes holes in the cell surface membrane to so this means the cell becomes freely permeable to all substances and dies
- 22B cells are involved in Humoral Immunity, Antibodies are soluble in blood and tissue fluid. What happens when an antigen enters blood?There will be one type of B cell that has an antibody which is complementary to the antigen. Which then divides by mitosis to form a clone of identical B cells
- 23The cloned B cells develop into Plasma cell or Memory cells Primary immune response ?Plasma cells produce immediate response but has short lifespan. These cells secrete antibodies which destroy pathogen and toxins it produces.
- 24Memory cells?have a longer life span. They circulate in the blood and tissue fluid and if they encounter they same antigen they rapidly divide and develop into plasma cells which produces antibodies that destroy the pathogen and they produce more memory cells ready for future infection
- 25Summary of role of B cells in Humoral Immunity* surface antigens of invading pathogens are taken up by B-cells
* b-cells process antigens and present on cell-surface
* T helper cells attach to these antigens and activate them
* Activated B-cells divide mitosis to give a clone of plasma cells
* Cloned plasma cells produce antibodies that fit antigens on the pathogens surface
* Antibodies attach to antigens and destroy the pathogen (1st Immune response)
* Some B cells develop into memory cells. (2nd immune response) - 26Antigenic variabilityIs where antigens on the pathogens surface is constantly changing
- 27AntibodiesThese are proteins made by B-cells which binds the antigen to form antibody-antigen complex.
* VERY SPECIFIC - 28Structure of ANTIBODY* Four polypetide chains
* Long chain = heavy chain
*Short chain = light chain
* Change shape by moving
* Binding site= fits very precisely onto the antigen
* binding site is different on different antibody = variable region - 29EACH SITE CONSISTS OF A SEQUENCE OF CONSTANT REGION IS..AMINO ACID THAT FORM A SPECIFIC 3D SHAPE
The rest of the antibody that is the same in all antibodies - 30—
- 31Monoclonal antibodyWHEN A SINGLE TYPE OF ANTIBODY IS ISOLATED AND CLONED
- 32FUNCTIONS OF ANTIBODIES *S *I *C *T* Separation of chemical from a mixture
* Immunoassay: calculating the amount of substance in a mixture. e.g. pregnancy testing kits
* Cancer treatment: monoclonal antibodies can be made that they only attach to cancer cells
* Transplant surgery - 33PRODUCING MONO CLONAL ANTIBODIES- Mouse is exposed to non-self material which requires antibodies
- B-cells in mouse produces antibodies and this is extracted from the spleen
- For the B-cells to divide, they are mixed with readily dividing cells e.g. cancer cells
- Detergent is added to break down the cell surface membrane so fuse together
- Fused cells are separated and each cell is cultured to form a group (clone).
- Each cell is tested to see if they produce an antibody
- Clones producing antibodies are grown on a large scale - 34Ethical issues of M-antibodyUse of mice: deliberately causing cancer
ethics of genetic engineering
Volunteers who suffered multiple organ failures - 35Passive immunity (antibodies received)Outside source
Natural= passing antibodies from mother to child
Artificial = injection of antibodies - 36Active immunity (antigens received)Long lasting
Natural- primary immune response following an infection
Artificial = vaccination - 37What do pathogens do>2. Pathogen(s) reproduce / cause disease (in host);
3. Damage cells / tissues / organs;
4. Release toxins; - 38Vaccines protect people against disease. Explain how1. Vaccines contain antigens are injected; weakened pathogens;
3. Memory cells made;
4. On second exposure memory cells produce antibodies
4. Idea of memory cells responding.
5. Rapidly produce antibodies / produces more antibodies;
5. Production of antibodies must be qualified for mark. Underlined ideas essential.
6. Antibodies destroy pathogens;
6. Accept bacteria/viruses etc but not disease
7. Herd effect / fewer people to pass on disease; - 39Features of successful vaccination- Economically available
- Few side effects
- Available means of storing, transporting, producing vaccines
- Means of administering vaccine
- Must be possible to vaccinate vast majority to produce a herd immunity - 40Why vaccine does not eliminate disease?- It may fail to induce immunity in certain individuals
- develop the disease immediately after vaccine
- pathogen may mutate
- so many varieties of pathogen
- pathogens that hide
- ethical objections to vaccine - 41Problems with cholera and vaccination- An intestinal disease so not easily reached by immune system
- Antigens of cholera may change
- mobile pop are difficult to vaccinate - 42TB and vaccination- Increase in HIV infection means more people with impaired immune system
- Poverty, war and political unrest
- Mobile pop
-elderly people so less effective immune systems
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- A-level Biology FlashCards sobre Immunity, criado por arunthathynair em 09-04-2015.
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- arunthathynair
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