2.4.4 defence against parasitic attack

Question 1

what aspects do the immune response in mammals have

Answer 1

non specific and specific

Question 2

what are examples of non specific defences

Answer 2

• physical barriers
• chemical secretions
• inflammatory response
• phagocytes
• natural killer cells destroying cells infected with viruses

Question 3

how do epithelial cells defend against parasites

Answer 3

they block the entry of parasites

Question 4

how do the hydrolytic enzymes defend against parasites

Answer 4

the enzymes in mucas, saliva and tears destroy bacterial cell walls

Question 5

how do low ph environments defend against parasites

Answer 5

the low ph environments of the secretions of stomach, vagina and sweat glands denatures cellular proteins of pathogens

Question 6

what happens if a cell becomes injured

Answer 6

releases signalling molecules that results in enhanced blood flow to the site, which brings antimicrobial proteins and phagocytes

Question 7

how do the powerful enzymes contained in lyosomes kill parasites

Answer 7

by engulfing them and storing them inside a vacuole in the process of phagocytosis

Question 8

what happens if natural killer cells identify and attach to cells infected with viruses

Answer 8

they release chemicals that lead to cell death by inducing apoptosis

Question 9

what are examples of specific cellular defences

Answer 9

a range of white blood cells that constantly circulate and monitor tissues

Question 10

what happens in a tissue becomes damaged or invaded

Answer 10

the cells release cytokines that increase blood flow resulting in non specific and specific white blood cells accumulating at the site of the infection or tissue damage

Question 11

why do mammals contain many different lymphocytes

Answer 11

because each lymphocytes possesses a receptor on its surface, which can potentially recognise a parasite antigen

Question 12

what happens once an antigen binds to a lymphocytes receptor

Answer 12

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

Question 13

how can lymphocytes defend

Answer 13

some produce antibodies. others can induce apoptosis in parasite infected cells

Question 14

antibodies possess regions where….

Answer 14

… the amino acid sequence varies greatly between different antibodies

Question 15

what does the region on antibodies where the amino acid sequence varies greatly between different antibodies give the antibody

Answer 15

its specifity for binding antigen

Question 16

what gives the antibody its specifity for binding antigen

Answer 16

the variable reion where the amino acid sequence varies greatly between different antibodies

Question 17

what happens once the antigen binds to the binding site

Answer 17

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 18

how are memory lymphocytes formed

Answer 18

the 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

Question 19

what is the benefit when a memory lymphocyte produces a secondary response when the same antigen enters the body in the future

Answer 19

this means antibody production is enhanced in terms of speed of production, concentration in blood and duration.