specific immune system

Question 1

define antigens

Answer 1

identifying chemical on the surface of a cell that triggers an immune response

Question 2

explain the difference between self and non-self antigens

Answer 2

• self: on surface of your own cells
• non-self: on surface of cells of pathogens

Question 3

define antibody

Answer 3

y-shaped glycoprotein made by B cells of the immune system in response to presence of an antigen

Question 4

define antigen-antibody complex

Answer 4

complex formed by binding of an antibody to an antigen

Question 5

define lymphocyte

Answer 5

WBC that make up the specific immune system

Question 6

define specific immune response

Answer 6

acquired immune response triggered by antigens which is able to distinguish between different pathogens

Question 7

describe the structure of antibodies

Answer 7

• glycoproteins of two identical long pp chains - heavy chains and 2 shorter identical chains - light chains
• chains held by disulfide bonds
• hinge region provides flexibility - allowing one antibody to bind to two separate antigens, one at each binding site

Question 8

describe 4 ways in which antibodies defend the body

Answer 8

• opsonins: antigen-antibody complex easily engulfed and digested by phagocytes
• pathogens can no longer effectively invade host cells when they are part of antigen-antibody complex
• agglutinins - cause pathogens carrying complexes to clump together - prevents them from spreading and easier to engulf multiple at same time
• anti-toxins - make toxins harmless

Question 9

define cell-mediated immunity

Answer 9

T lymphocytes respond to cells of an organism that have been changed in some way

Question 10

what is cell-mediated immunity effective against

Answer 10

virus infections and early cancers

Question 11

describe the process of cell-mediated immunity

Answer 11

• macrophages phagocytose pathogens, process antigens and form antigen-presenting cells
• T helper cell with complementary surface receptors to non-self antigens binds to APC
• T helper cell is stimulated to undergo mitosis to form many clones that differentiate into:
• T killer cells - destroy pathogen using perforins and toxins that trigger apoptosis
• T helper cells - secrete interleukins to stimulate phagocytosis and B cell division
• T memory cells - immunological memory of pathogen
• T regulatory cells - suppress immune response when pathogen removed

Question 12

define humoural immunity

Answer 12

B lymphocytes produce antibodies in response to antigens pathogens outside cells

Question 13

suggest what humoural immunity is particularly effective against

Answer 13

bacteria and fungi

Question 14

describe the process of humoural immunity

Answer 14

• B cell with complementary surface receptor to pathogen binds to it and engulfs
• antigens are processed, B cell becomes APC
• T helper cell with complementary receptor to presented antigen binds to the APC - clonal selection
• T helper cells induced to secrete interleukins
• interleukins stimulate B cell to divide by mitosis, produce many clones of that B cell variant - clonal expansion
• the B cell then differentiates into:
• plasma cells - secrete antibodies that fit the antigens on pathogens
• B memory cells - retain immunological memory of that pathogen, stored in lymphatic tissue
• secretion of many specific antibodies by plasma cells that circulate in blood and act as: opsonins, agglutinins, anti-toxins act against pathogens - defence

Question 15

define clonal selection

Answer 15

exposure to a specific antigen selectively stimulates the proliferation of the cell with the appropriate antibody to form numerous clones of these specific antibody-forming cells

Question 16

define proliferation

Answer 16

rapid growth or production of cells by multiplication of parts

Question 17

define clonal expasion

Answer 17

mass proliferation of antibody-producing cells by clonal expansion

Question 18

summarise the role of antigen presentation in specific immune response.

Answer 18

ensures that specific immune response can be initiated through recognition by T cells

Question 19

describe the role of cell signalling in the specific immune response.

Answer 19

cell signalling that occurs - interleukins

Question 20

define primary immune response

Answer 20

relatively slow production of small number of correct antibodies the first time a pathogen is encountered

Question 21

define secondary immune response

Answer 21

relatively fast production of very large quantities of the correct antibodies a second time a pathogen is encountered as a result of immunological memory