cell recognition and the immune system

Question 1

what is immunity?

Answer 1

is when the body is better prepared to deal with a pathogen usually after it has already been infected once.

Question 2

what are the two types of lymphocytes?

Answer 2

T lymphocytes are involved in cell-mediated responses

B lymphocytes are involved in humeral response.

Question 3

what is an antigen?

Answer 3

a molecule usually a protein that induces an immune response, it is a molecule that is recognised as non-self.

Question 4

what are the key things that the proteins can detect?

Answer 4

pathogens, non self cells, toxins, abnormal body cells.

Question 5

how do lymphocytes recognise cells that belong to the body?

Answer 5

in the foetus lymphocytes are constantly colliding with other cells- where infection is rare as t is protected by the mother (placenta) therefore they will collide with almost exclusively body cells. the cells that react to the body cells die or are suppressed. the only ones remaining are those that might fit foreign material and therefore only respond to foreign material.

in adults lymphocytes are found in the bone marrow. if any of these lymphocytes produce an immune response they undergo programmed cell death (apoptosis)

Question 6

what are the two types of white blood cell?

Answer 6

phagocytes and lymphocytes.

Question 7

what is a phagocyte and what does it do?

Answer 7

a phagocyte is a type of white blood cell (e.g. a macrophage) engulf and destroy a pathogen via phagocytosis.

Question 8

how does a phagocyte work?

Answer 8

firstly the phagoyste recognises the foreign antigens on a pathogen. the phagocyte then engulfs the pathogen to form a vesicle called a phagosome. lysosomes then love towards the vesicle and fuse with it. enzymes called lysozmes are present within the lysosome, these break down the pathogen via by the hydrolysis of their cell walls. the phagocyte then presents the pathogens antigens.

Question 9

what is a B lymphocyte?

Answer 9

otherwise known as a B cell are so called because they mature in the bone marrow. they are associated with humeral immunity

Question 10

what is a T lymphocyte?

Answer 10

T cells are formed in the thymus gland are associated with a cell meditated response.

Question 11

what is cell meditated immunity?

Answer 11

lymphocytes respond to an organisms own cells that have been infected by non-self material from a different material and also cells that are genetically different.

Question 12

how can a T lymphocyte tel the difference between invader cells?

Answer 12

phagocyte that have presented a pathogens antigens on their own cell membranes
body cells present some of the viral antibodies on their membrane if they have been infected
transplanted cells have different antigens
cancer cells are different body cells and present antigens on their membrane.

Question 13

what are the stages of T lymphocytes in rospose to a pathogen?

Answer 13

when a pathogen is taken in by phagocytes or invade a cell, the T helper cell attaches its self to the antigen which it id specific to and then begins to rapidly clone genetically identical T cells
the clone cells develop into memory cells, stimulate phagocytes to engulf the pathogens, stimulate B cells to divide and recreate their antibody, activate cytotoxic T cells which release perforin.

Question 14

how do cytotoxic T cells kill infected cells?

Answer 14

the produce a protein called perforin that makes holes in the cell surface membrane this means that the cell be ones freely permeable to all substances and the cell dies as a result.

Question 15

what is humeral immunity?

Answer 15

humoral immunity involves antibodies which are soluble in the blood and tissue fluid. there are many different B cells each producing a specific antibody that is specific for a individual antigen.

Question 16

what happens when a B cell detects a antigen?

Answer 16

when a b cell detects a specific antigen, the antigen enters the B cell via endocytosis and gets presented on its surface. the Thcell attaches to this b cell and orders it to divide this forms an identical B cell of which produce the antibody that is specific to that antigen- called clonal selection

Question 17

what are monoclonal antibodies?

Answer 17

as each clone produces one specific antibody

Question 18

what are plasma cells?

Answer 18

b cells that secrete antibodies into the blood - these cells can only survive for a few days but each make around 2000 antibodies every second

Question 19

what are memory cells?

Answer 19

b cells responsible for secondary immune response. when they encounter an antigen at a later date they dede rapidly into plasma cells or more memory cells

Question 20

what are antibodies?

Answer 20

antibodies are proteins with specific binding sites synthesised by T cells. each antibody has two identical binding sites which are complementary to a specific antigen, mass variation can occur as they are made of proteins.

Question 21

what is the structure of an antibody?

Answer 21

antibodies consist of 4 polypeptide chains. the chains of one pair are long and are called heavy chains and the others are called light. each antibody has a specific binding site that forms an antigen-antibody complex. binding site is different and so os therefore called the variable region, the rest of the antigen is known as the constant region.

Question 22

how do antibodies lead to the destruction of pathogens?

Answer 22

agglutination of bacterial cells. clumps of bacterial cells are formed
thy serve as markers to that stimulate phagocytes to engulf the bacterial cell.

Question 23

what are the functions of antibodies in medicine and science.

Answer 23

targeting medication to specific cell types by attaching a therapeutic drug to an antibody

• e.g. monoclonal antibodies that are specific to a cancer cell are produced and then given to a patient and then attach themselves to the receptors on the cell, they attach to the surface of the cancer cells and block the chemical signals that stimulate uncontrolled growth.
• lead to fewer side affects

medical diagnosis

pregnancy testing

Question 24

what is indirect monoclonal antibody therapy?

Answer 24

where a cytotoxic drug or a radioactive substance is attached to the monoclonal antibody so that when it attaches to the cancer cells it kills them.

Question 25

what are the ethics of using monoclonal antibodies?

Answer 25

producing monoclonal antibodies involves the use of mice in which they are used to produce both the antibodies and the tumour cells, the mice are then euthanised at the end

there have been some tests that relate to monoclonal antibodies

testing the drugs on people may have serious side affects.

Question 26

what is active immunity?

Answer 26

active immunity is produced by stimulating the production of antibodies by the individuals own immune system. direct contact with the antigen or pathogen is necessary. immunity takes time to develop. it is generally long lasting and of two types:
natural active immunity results in an individual becoming infected with a disease under normal conditions and then the body produces its own antigens.
artificial active immunity forms the basis of a vaccination it involves activating an immune response from a n individual without them suffering the symptoms of disease.

Question 27

what is passive immunity?

Answer 27

it is produced by the introduction of antibodies into individuals from an outside source. no direct contact with pathogen or antigen is necessary to induce immunity.
immunity is acquired instantly. no memory cells are formed.

Question 28

how can vaccines be administered?

Answer 28

by mouth or by injection.

Question 29

what are the features of a successful vaccination program?

Answer 29

a suitable vaccine must be economically available
there must be few side effects if any from vaccination.
means of producing, storing and transporting must be available.
there must be the means of administering the vaccine property at the appropriate time - training staff
it must be possible to vaccinate large majorities of the vulnerable population in order to create herd immunity.

Question 30

why is herd immunity important?

Answer 30

it is never possible to vaccinate everyone in a large population. for example babies and young children are not vaccinated as their immune systems are not yet fully functional

Question 31

why may vaccinations not eliminate a disease?

Answer 31

the vaccination may fail to induce immunity in certain individuals
somebody might develop the disease straight after the vaccination an therefore has not built up a sufficient immunity levels
the pathogen may mutate frequently and there for the antigens on the outside of it will change, this means that vaccinations suddenly become ineffective against the new pathogen and so the antibodies are not produced, immunity is as a result short lived
there may be too many variations of a pathogen to develop a vaccine that is effective against all of them.
certain pathogens hide from the immune system
individuals may object to the vaccination.

Question 32

what are the ethics of using vaccines.

Answer 32

the preduction of vaccines and the development often used animals
vaccines can cause side-effects that sometimes can cause long term harm
on whom should they be tested?
who deserves to get the vaccine first

Question 33

what does HIV stand for?

Answer 33

human immunodeficiency virus

Question 34

what does AIDS stand for?

Answer 34

acquired immune deficiency syndrome

Question 35

what group of viruses does HIV belong to?

Answer 35

retro viruses

Question 36

how does HIV cause the symptoms of aids?

Answer 36

the HIv specifically attacks T Helper cells , killing or interfering with the normal function of them. in a healthy human there is about 800-1200 helper t cells in every mm3 where as with somebody with aids there is only run 200. without an adequate number of T helper cells, the immune system cannot stimulate B cells to produce antibodies or the cytotoxic T cells that kill pathogens.

Question 37

what does ELISA stand for?

Answer 37

enzyme linked immunosorbent assay.

Question 38

what is apoptosis?

Answer 38

programmed cell death