4.1 Secondary animal defences/immune system

Question 1

define the term: immune response

Answer 1

the way in which white blood cells respond to infection by pathogens

Question 2

define the term: antigen

Answer 2

specific chemical maker/ proteins on the outer membrane of pathogens recognized as foreign by the immune system

Question 3

define the term: antibody

Answer 3

a small globular protein produced in plasma cells secreted by B lymphocytes in response to a particular antigen, antibody is specific to antigen and is stimulated by that antigen

Question 4

what are the two main groups of leucocytes (white blood cells)?

Answer 4

phagocytes (neutrophils and macrophages)
lymphocytes (B-cells and T-cells)

Question 5

where are neutrophils found?

Answer 5

• manufactured in bone marrow
• travel in blood and are sometimes in the tissue fluid

Question 6

longevity of neutrophils?

Answer 6

• short lived as die after digesting pathogens

Question 7

function of neutrophils

Answer 7

they engulf and digest pathogens and the die after doing so
- dead neutrophils may collect in an area of infection to form pus

Question 8

features of neutrophils

Answer 8

• multi-loped nucleus
• contain lots of lysosomes

Question 9

where are macrophages found?

Answer 9

• manufactured in the bone marrow
• travel in blood as monocytes
• many are found in lymph nodes
• may be found in more peripheral tissues

Question 10

longevity of macrophages?

Answer 10

long lived

Question 11

function of macrophages

Answer 11

• engulfs pathogen
• moves antigen to the surface of the cell to become an antigen presenting cell which exposes the antigen to the other cells of the immune system so they can recognise the antigen
• has a special protein complex so other phagocytes don’t attack it

Question 12

what is opsonin?

Answer 12

protein molecules that attach to antigens on pathogens to enhance the ability of phagocytes to bind and engulf the pathogen

Question 13

function of T helper cells

Answer 13

• release cytokines that stimulate B cells to develop and stimulates the B cells to develop
• stimulates phagocytosis by the phagocytes

Question 14

function of killer T cells

Answer 14

attack and kill host-body cells that display the foreign antigen

Question 15

function of T memory cells

Answer 15

provides long term immunity

Question 16

function of T regulator cells

Answer 16

shut down the immune response after the pathogen has been removed
- help prevent autoimmunity

Question 17

function of B plasma cells

Answer 17

circulate in the blood, manufacturing and releasing antibodies

Question 18

function of B memory cells

Answer 18

remain in the blood for a number of years and provide long term immunity

Question 19

immune response

Answer 19

1. pathogen enter the body
2. macrophage ingests the pathogen and display the antigen fragments on their cells surface = APC
3. T helper cells recognise antigen so interact, macrophage releases a chemical alarm signal called interleukin 1 which stimulates T helper cells to release interleukin 2
4. interleukin 2 causes clonal expansion by mitosis of certain killer T cells and B cells
5. separates two ways (other flashcards)

Question 20

immune response part 2: killer T cells

Answer 20

1. each type of killer T cells is able to recognise a particular antigen
2. so bind to infected cells with that antigen on their surface and produce chemicals that kill infected cells
3. resulting in destruction of the pathogen

Question 21

immune response part 2: B cells

Answer 21

1. B cells are able to recognise particular antigen
2. B cells become activated by T helper cells they differentiate into B plasma cells
3. B plasma cells become antibody producing factories flooding the bloodstream with antibodies that bind to antigen marking them for destruction by macrophages
4. some become B memory cells so the secondary immune response to a future infection by the same pathogen is swifter and stronger-what gives you immunity.

Question 22

define term autoimmune disease

Answer 22

when the immune system attacks a part of the body (tissues and cells)

Question 23

describe what happens in autoimmune diseases

Answer 23

antibodies start to attack our own antigens and our B and T cells which are specific to our antigens are destroyed on early development

Question 24

examples of autoimmune diseases

Answer 24

1. arthritis: painful inflammation of a joint, cause is unknown but starts with the antibodies attacking membranes around the joint
2. lupus: cause swelling and pain in parts of the body because antibodies that attack certain proteins in the nucleus in cells and affected tissues

Question 25

what is the structure of an antibody ?

Answer 25

• Y-shaped
• consist of four polypeptide chain
  -light polypeptide chain and heavy polypeptide chain
• disulfide bridge to hold polypeptide chains in place
• variable region on end of light polypeptide chain which is complementary to shape of antigen
• constant region which is the same for all antibodies
• hinge to allow flexibility so molecule can grip more than one antigen

Question 26

what are the main groups which summaries the way antibodies work?

Answer 26

opsonin, agglutinins and anti-toxins

Question 27

what is opsonization?

Answer 27

antibodies have 2 binding sites and an end that stimulates phagocytosis
pathogen with specific antigen binds to antibody and then phagocytosis happens so a phagocyte engulfs antibody and pathogen

Question 28

what is agglutination?

Answer 28

antibodies clump several pathogens together which crosslinks pathogens making it non-infective and easily phagocytosed

Question 29

anti- toxins

Answer 29

antibody binds wit toxin making it harmless