Disease and Immunity

Question 1

what are pathogens

Answer 1

microorganisms that cause disease

Question 2

How does the skin act as a defence against pathogens

Answer 2

acts as physical + chemical barrier. Skin cells release oleic acid that kills bacteria and lowers pH so difficult for pathogens to colonise.

Question 3

skin cells sometimes secrete lysozyme, what is the purpose of this?

Answer 3

is an enzyme that can breakdown carbohydrates in cell wall of some bacteria

Question 4

How do mucous membranes defend against pathogens

Answer 4

protect body openings exposed to environment by secreting muscus which traps pathogens + contain antimicrobial enzymes, cilia then wafts mucus to digestive system where it is digested.

Question 5

outline process of inflammation

Answer 5

mast cells release histamine and cytokines, this attracts platelets to wound, dilation of capillaries and increased permeability of capillaries. Increases blood flow and white blood cells.

Question 6

what is purpose of opsonins

Answer 6

bind to pathogen and ‘tag’ it, phagocytes have receptors on surface for opsnonins so increases chance of pathogen being phagocytosed.

Question 7

How are wounds repaired to prevent pathogens entering

Answer 7

skin cells divide and migrate to edges of wound. tissue below contracts to bring edges of wound close, then repaired using collagen fibres.

Question 8

name three plant defences

Answer 8

waxy cuticle - waterproof, prevents water collecting on leaf reduces risk waterborne infections.
callose deposition- between cell walls + plasma membranes, makes hard for pathogens to enter cells.
release of antimiocrobial chemicals eg. saponins destroy cell membrane of fungi

Question 9

what do T helper cells release to activate B lymphocytes

Answer 9

interleukins (cytokines) - bind to receptor on B lymphocyte

Question 10

what is the purpose of the hinge region

Answer 10

allows flexbility when antibody attaches to antigen

Question 11

What is the name for when antibodies bind to 2 pathogens at same time clumping them together

Answer 11

agglutinating

Question 12

does the primary response use memory cells

Answer 12

no

Question 13

what is active immunity

Answer 13

when body makes its own antibodies and memory cells

Question 14

what is passive immunity

Answer 14

when body is given antibodies made by different organism

Question 15

do vaccinations provide immunisation

Answer 15

no they cause immunisation

Question 16

what is the name for a weakened or dead pathogen

Answer 16

attenuated pathogen

Question 17

what is herd immunity

Answer 17

when a large enough population of people are vaccinated, those who are not are unlikely to catch the disease

Question 18

outline the non specific immune response

Answer 18

phagocytes recognise antigens presented on pathogen, cytoplasm of phagocyte move around pathogen (with help of opsonins). Inside pathogen held in vesicle called phagosome. lysosome fuses with phagosome breaking it down. phagocyte may present pathogens antigens on surface to alert immune system .

Question 19

outline a cell mediated response

Answer 19

T lymphocyte’s receptors bind to complimentary antigen presented by APC,
this activates T lymphocyte (clonal selection) and then undergoes clonal expansion into T helper, T killer or T regulatory cells. Some T cells become memory cells.

Question 20

outline a Humoral response

Answer 20

antibodies bind to complimentary antigens, forming antigen-antibody complexes. T helper cells secrete interleukins to help activate B lymphocytes which then undergo clonal expansion into memory cells or plasma cells.

Question 21

what is antibiotic resistance?

Answer 21

occurs when there is a genetic mutation in a population of bacteria allowing it to resist antibiotics

Question 22

what can antibiotic resistance lead to

Answer 22

an allele for antibiotic resistance to be passed on to its offspring Eg. MRSA

Question 23

where did penicillin origionate from

Answer 23

penecillium mold (fungus)

Question 24

where did digitalis origionate from

Answer 24

foxglove

Question 25

where did aspirin origionate from

Answer 25

willow

Question 26

where did morphine origionate from

Answer 26

opium poppy