2.5d Defence Against Parasitic Attack

Question 1

Explain immune response in mammals

Answer 1

there is both non-specific and specific aspects

Question 2

What are examples of non-specific defences?

Answer 2

• physical barriers
• chemical secretions
• inflammatory response
• phagocytes
• natural killer cells

Question 3

What is the basic role of natural killer cells?

Answer 3

destroy cells infected with viruses

Question 4

What is the role of epithelial tissue in the nun-specific response?

Answer 4

block the entry of parasites

Question 5

What destroys bacterial cells walls?

Answer 5

• hydrolytic enzymes in mucus, saliva and tears

Question 6

What is the role of hydrolytic enzymes in mucus, saliva and tears in the non-specific response?

Answer 6

destroy bacterial cell wall

Question 7

What is the role of the low pH environments of the secretions of stomach, vagina and sweat glands in the non-specific response?

Answer 7

denatures cellular proteins of pathogens

Question 8

What causes the denaturing of cellular proteins in the non-specific response?

Answer 8

the low pH environments of the secretions of stomach, vagina and sweat glands

Question 9

What happens with injured cells in the non-specific response?

Answer 9

• they release signalling molecules
• This results in enhanced blood flow to the site, bringing antimicrobial proteins and phagocytes.

Question 10

Explain the process of phagocytosis?

Answer 10

• Killing of parasites using powerful enzymes contained in lysosomes
• engulfing them and storing them inside a vacuole

Question 11

What is the role of natural killer cells?

Answer 11

• identify and attach to cells infected with viruses
• releasing chemicals that lead to death by inducing apoptosis

Question 12

What is the simplified role of the specific cellular defences?

Answer 12

a range of white blood cells constantly circulate, monitoring the tissues

Question 13

What happens if tissues become damaged or invaded?

Answer 13

• cells release cytokines that increase blood floe
• resulting in non-specific and specific white blood cells accumulating at the site of infection or tissue damange

Question 14

what is the role of a specific receptor on the surface of a lymphocyte?

Answer 14

it can potentially recognise a parasite antigen

Question 15

What happens when an antigen binds to a lymphocytes receptor?

Answer 15

• selects that lymphocyte to then divide and produce a clonal population of this lymphocyte

Question 16

What are different things that lymphocytes can do?

Answer 16

• some will produce antibodies
• others can induce apoptosis in parasite infected cells

Question 17

Explain the structure of antibodies

Answer 17

• possess regions where the amino acid sequence varies greatly between different antibodies
• the variable region gives the antibody its specificity for binding antigen

Question 18

What happens when an antigen binds to the variable region of an antibody?

Answer 18

• the antigen-antibody complex formed can result in inactivation of the parasite, rendering it susceptible to a phagocyte, or can stimulate a response that results in cell lysis

Question 19

Explain memory cell lymphocytes

Answer 19

• Initial antigen exposure produces memory lymphocyte cells specific for that antigen that can produce a secondary response when the same antigen enters the body in the future.
• When this occurs antibody production is enhanced in terms of speed of production, concentration in blood and duration.