Immunity

Question 1

Innate defences (non-specific resistance) - first line

Answer 1

Mechanical barriers - skin, mucous membranes
Chemical barriers - stomach acid, lysozyme

Question 2

Innate defences (non-specific resistance) - second line

Answer 2

Antimicrobial proteins
Natural killers cells (NK cells)
Phagocytes
Inflammation
Fever

Question 3

Adaptive defences - immunity or specific resistance

Answer 3

Specific invading pathogens
Specificity - individual agents are different
Memory - second response is greater and faster
Antigens - non-self
Antigen receptors on lymphocytes

Question 4

Immunocompetence

Answer 4

Recognise specific antigens

Question 5

Formation of lymphocytes

Answer 5

T cells develop in thymus
B cells develop in red bone marrow
Antigen-activating Immunocompetence lymphocytes - effector and memory cells

Question 6

B cells (lymphocytes)

Answer 6

Develop in red bone marrow
Once stimulated they clone to become plasma cells which produce antibodies; immunoglobulins (Ig)
Antibody mediated or humoral response

Question 7

Antibody-antigen actions

Answer 7

Neutralisation - enhances phagocytosis
Agglutination - enhances phagocytosis
Precipitation - enhances phagocytosis
Complement - enhances phagocytosis and inflammation, leads to cell lysis

Question 8

Antibodies (immunoglobulins) classes

Answer 8

IgG - main antibody and able to cross placenta
IgA - secretory antibody
IgM - released into plasma, indicates current infection
IgE - associated with allergies and parasitic infections
IgD - attached to B cells, antigen receptor

Question 9

T cells (lymphocytes)

Answer 9

Migrate to thymus to continue development
Cell mediated immune response - intracellular pathogens
T killer cells - directly attack antigen
T helper cells - help both antibody-mediated and cell mediated responses

Question 10

Memory cells

Answer 10

‘Memory’ of invading antigen
Allows the second and subsequent response to be quicker and much greater
End result - signs and symptoms are not seen

Question 11

Primary response

Answer 11

Slow and ineffective
Signs and symptoms are seen
Occurs after a delay

Question 12

Secondary response

Answer 12

Mulch faster and greater
Signs and symptoms not seen
Memory cells

Question 13

Humeral immunity - active

Answer 13

Natural - infection; contact with the pathogen
Artificially - vaccine; dead or attenuated pathogen

Question 14

Humeral immunity - passive

Answer 14

Natural - antibodies passed from mother to fetus via placenta or infant in her milk
Artificially - injection of immune serum (gamma globulin)

Question 15

Autoimmune responses

Answer 15

Fails to recognise the body cells/tissues as self
The immune system attacks its own tissues

Question 16

Autoimmune diseases - multiple sclerosis (MS)

Answer 16

Destroys the myelin (white matter) of the nervous system

Question 17

Autoimmune diseases - rheumatoid arthritis

Answer 17

Destroys the cartilage of joints

Question 18

Autoimmune diseases - type 1 (insulin-dependent) diabetes mellitus

Answer 18

Destroys insulin producing cells of the pancreas

Question 19

Autoimmune diseases - glomerulonephritis

Answer 19

Destroys the functional units (nephrons) of the kidney

Question 20

Autoimmune diseases - myasthenia gravis

Answer 20

Impairs communication between nerves and skeletal muscle by destroying receptor sites

Question 21

Allergy

Answer 21

When a person reacts to a substance normally tolerated by most other people
Antigens = allergens
E.g. pollen, dust mites, diary products, sea food

Question 22

Allergy - sensitisation stage

Answer 22

Allergen invades
Plasma cells - IgE antibodies which attach to mast cells in body tissues and to circulating basophils

Question 23

Allergy - subsequent responses

Answer 23

Allergen combines with IgE
Triggers degranulation and release of histamine and other chemicals
Histamines - blood vessels dilate and leaky; promote edema, secretion of mucus, smooth muscle contract

Question 24

Hypersensitivity reactions - anaphylactic reactions

Answer 24

Breakdown of mast cells and basophils
Result in an anaphylactic shock

Question 25

Hypersensitivity reactions - cytotoxic reactions

Answer 25

Typical of incompatible blood transfusions
Results in destruction of cells

Question 26

Hypersensitivity reactions - immune complex reactions

Answer 26

Results in the destruction of tissue
E.g. rheumatoid arthritis, glomerulonephritis

Question 27

Hypersensitivity reactions - delayed hypersensitivity reactions

Answer 27

Appear 12-72 hours after exposure
E.g. the Mantoux skin test for TB