Immunity & Disease

Question 1

What are the 2 main pathways involved in immunity?

Answer 1

1) Innate

2) Adaptive

Question 2

Describe innate immunity?

Answer 2

Occurs initially even before infection or is activated in a non-specific way

Question 3

Describe adaptive immunity?

Answer 3

A cell-mediated response led by antigens and anti-bodies

Question 4

What 4 things are involved in innate immunity?

Answer 4

1) Physical barriers
2) Chemical barriers
3) Cellular defence mechanisms
4) Non-specific defence mechanisms (caused by Inter-leukins released from macrophages)

Question 5

Name the 2 physical barriers?

Answer 5

1) Skin

2) Mucous membranes

Question 6

How does the skin act as a physical barrier?

Answer 6

1) Keratin outer layer
2) Dead skin cells fall off
3) Sweat contains anti-microbial chemicals

Question 7

How do the mucous membranes act as a physical barrier?

Answer 7

1) The normal flow of mucous across the membranes washes the microbes away
2) Cilia (in respiratory tract)
3) Acid (in the stomach)
4) Enzymes (e.g. saliva)

Question 8

Describe the chemical barriers in the body?

Answer 8

Chemical mediators are released from proteins.
Complement proteins = work with the body’s defence mechanisms
Interferons proteins = inhibit the replication of viruses

Question 9

What are the 2 cellular defence mechanisms?

Answer 9

1) Granulocytes that carry out phagocytosis

2) Macrophages

Question 10

Which cells are classed as granulocytes and carry out phagocytosis?

Answer 10

Neutrophils, basophils, eosinophils

Question 11

How are the macrophages involved in cellular defence mechanisms?

Answer 11

In tissue = called monocytes
When activated = called macrophages
Macrophages will stimulate non-specific defence mechanisms (by releasing inter-leukin 1 and 6) and stimulates specific-defence mechanisms (by presenting antigens on their surface)

Question 12

What are the 3 non-specific defence mechanisms that are stimulated by macrophages releasing interleukins?

Answer 12

1) Fever
2) Pain, swelling and redness
3) Acute-phase proteins are released from the liver, will bind to proteins and stimulate complement proteins

Question 13

Which cells are involved in the adaptive immune response?

Answer 13

Lymphocytes

Question 14

Where are the lymphocytes located?

Answer 14

Make up 1% of the blood stream and the majority are located in the lymphatic system

Question 15

Name the 2 lymphocytes involved in adaptive immunity?

Answer 15

B-cells and T-cells

Question 16

Compare where the B-cells and the T-cells are produced and where they mature?

Answer 16

Both B-cells and T-cells are produced in the bone marrow.
But, the B-cells mature in the bone marrow whereas the T-cells mature in the thymus gland.
Once mature, they both circulate in the blood and lymphatic system

Question 17

Compare the roles of B-cells and T-cells?

Answer 17

B-cells: Humoral immunity, release antibodies and present antigens on their surfaces to activate T-cells
T-cells: Cell-mediated immunity

Question 18

Compare what B-cells and T-cells recognise?

Answer 18

B-cells: Recognise antigens outside of the cell

T-cells: Recognise antigens presented on the surface of other cells

Question 19

Compare the of B-cells and T-cells?

Answer 19

B-cells: Only 1 type

T-cell: 2 types

Question 20

Describe the 2 types of T-cells and their function:

Answer 20

CD8 (cytotoxic) T-cells: Attacks pathogens
CD4 (helper) T-cells: 1) Help the B-cells to release antibodies and 2) Activates CD8 T-cells and macrophages in order to attack the pathogens

Question 21

What is an antigen?

Answer 21

A protein marker on a cell’s surface

Question 22

What is an Epitope?

Answer 22

A fragment of an antigen

Question 23

How does HIV cause a diminished immune system?

Answer 23

HIV (human immunodeficiency virus) destroys T-helper cells (CD4) which causes a diminished immune system and results in AIDS (acquired immunodeficiency syndrome)

Question 24

Describe the immune response in steps (starting with the innate immune response and then the adaptive immune response):

Answer 24

Innate immune response:
Granuloytes will carry out phagocytosis and macrophages will present the pathogens antigens on its surface.
Adaptive Immune response:
1) B-cells will recognise the antigen product specific antibodies and present the antigen on its surface
2) CD4 T-helper cells recognise the antigen presented by the B-cell and help the B-cells to secrete antibodies
3) The B-cells will divide into plasma cells (that release antibodies) and memory cells.
4) CD4 T-helper cells will then activate macrophages and CD8 cytotoxic T-cells to directly destroy the pathogen

Question 25

What 3 problems can occur with the immune system?

Answer 25

1) Immunodeficiency
2) Over activity/hypersensitivity
3) Autoimmunity

Question 26

Name 5 examples that causes immunodeficiency?

Answer 26

1) HIV
2) Splenoctomy
3) Organ Transplant
4) Chemotherapy
5) Bone marrow dysfunction

Question 27

Name 2 examples caused by an over active immune system?

Answer 27

1) Allergy

2) Sepsis

Question 28

Define autoimmunity and what causes it?

Answer 28

Autoimmunity is whereby the body is unable to recognise self cells and so the immune system will fight against self cells.
It is caused because:
(Normally when the embryo is developing, lymphocytes that recognise self-cells are deactivated and destroyed) But in autoimmunity, these self-recognising lymphocytes are reactivated.

Question 29

Name 4 examples of autoimmunity diseases?

Answer 29

1) Multiple sclerosis
2) Rheumatoid Arthritis
3) Type 1 diabetes
4) Coeliac disease

Question 30

When is the immune system manipulated?

Answer 30

1) Organ transplantation - suppressing the immune system so the body is less likely to reject the organ
2) Immunotherapy - in cancer
3) Immunisation/vaccination - introducing an inactivated pathogen to the body, so B-cells can produce specific antibodies to it. Memory B-cells are formed so that if injected again with the same pathogen, these memory B-cells can produce the specific antibodies against it.

Question 31

What are the 4 types of vaccination/immunisation?

Answer 31

1) Live (but weakened)
2) Inactivated
3) Taxoid (bacterical toxin)
4) Conjugated (antigen linked to a protein carrier)