Immune System

Question 1

Bacteria

Answer 1

prokaryote, unicellular organisms with DNA in the form of plasmids contained in cytoplasm, flagella, slime layer, cell membrane and wall

Question 2

Virus

Answer 2

agents containing either RNA or DNA, with a protein coat. some have lipid envelopes

Question 3

External Defences

Answer 3

Skin, mucus, hairs, cilia, acids

Question 4

Protective reflexes

Answer 4

coughing, sneezing, vomiting and diarrhoea

Question 5

Monocytes & Marcophages

Answer 5

monocytes differentiate into macrophages, which either look for pathogens or remain in a fixed place. particularly important in removing microbes and dying cells

Question 6

Neutrophils

Answer 6

a granulated leucocyte, the first cells to move into the tissue to destroy the pathogen by phagocytosis

Question 7

Dendritic cells

Answer 7

characterised by projections from cytoplasm, have the ability to detect, engulf and process foreign particles

Question 8

Complement system

Answer 8

system of plasma proteins capable of being activated by pathogens or antibodies

Question 9

Pyrogen

Answer 9

proteins that are capable of inducing a fever response, by being released during an inflammatory response, and stimulating the hypothalamus to reset the body’s internal thermostat

Question 10

Histamine

Answer 10

chemical that causes vasodilation during the inflammatory response, and thus increases the permeability of the capillaries of the affected area

Question 11

Heparin

Answer 11

chemical that prevents clotting. a clot of the fluid forms around the damaged area, which slows the spread of the pathogen into healthy tissues

Question 12

Mast cells

Answer 12

type of granulocyte, capable of releasing various chemicals such as pyrogens and histamine and heparin

Question 13

B-cells

Answer 13

lymphocytes that are produced and mature in the bone marrow, before becoming part of the lymphoid tissues

Question 14

T-cells

Answer 14

lymphocytes that are produced in the bone marrow, mature in the thymus, before becoming part of the lymphoid tissues

Question 15

Antigens

Answer 15

any substance capable of causing a specific immune response. they include virus particles, whole micro-organisms, parts of bacteria, toxins, molecules on cells

Question 16

Antibodies

Answer 16

specialised proteins produced by plasma cells in response to a non-self antigen. belong to group of proteins called immunoglobulins

Question 17

Antigen-presenting cells

Answer 17

specific cells that recognise non-self antigens and respond by: detecting the presence of a non-self antigen, engulfing the pathogen, digesting the pathogen, producing small fragments that move to the cell’s surface, and then presenting the antigen to lymphocytes

Question 18

How antibodies work

Answer 18

• inactivating foreign enzymes or toxins by combining with them or inhibiting their reaction with other substances
• binding to the surface of viruses and preventing them from entering cells
• coating bacteria so that they are more easily consumed by phagocytes
• causing particles to clump together, i.e. agglutination
• dissolving organisms
• making soluble substances insoluble