diseases and immunity

Question 1

what is a pathogen

Answer 1

a disease causing organism

Question 2

what is a transmissible disease

Answer 2

a disease in which the pathogen can be passed from one host to another

Question 3

how is pathogen transmitted

Answer 3

• transmission can occur through direct contact: by blood and body fluids
• can also occur through indirect contact: contaminated surfaces, from food, from air, from animals

Question 4

what are the body defences against disease

Answer 4

the skin, hair in nose, mucus, stomach acid, white blood cells

Question 5

how does skin defend against disease

Answer 5

the outer layer of skin, epidermis, is waxy and impermeable to water and to pathogens

Question 6

how do nose hairs defend against disease

Answer 6

they act as a filter that prevents dust, pollen and allergens from entering your lungs. Barrier to infection.

Question 7

how does hydrochloric acid in stomach defend against disease

Answer 7

it protects the body against pathogens ingested with food or water, it kills the bacteria

Question 8

how does mucus defend against disease

Answer 8

it traps pathogens before they can enter the lungs. when mucus is removed by blowing nose, any pathogens trapped are removed too.

Question 9

how do wbc defend against disease

Answer 9

they must attack only invading organisms. Antibody production by wbc destroy antigens on surfaces of pathogens

Question 10

how does clean water supply control the spread of disease

Answer 10

contaminated water and poor sanitation are linked to transmission if diseases such as cholera, diarrhoea, lyphoid and polio

Question 11

how does hygenic food preparations control the spread of disease

Answer 11

microorganisms might be decomposers and spoil the food. they might be pathogenic and cause disease

Question 12

how does good personal hygiene control the spread of disease

Answer 12

it protect yourself from getting gastro or infectious diseases. washing hands removes germs that can make you ill

Question 13

how does waste disposal control the spread of disease

Answer 13

waste accumulates and could not acts as a breeding ground for organisms which transmit disease

Question 14

how does sewage treatment control the spread of disease

Answer 14

prevents groundwater and water pollution that could lead to tainted drinking water

Question 15

what is active immunity

Answer 15

defence against a pathogen by antibody production in the body. It is gained after an infection by a pathogen or vaccination – long term

Question 16

what are antibodies

Answer 16

proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes

Question 17

what is the process of vaccination

Answer 17

1) weakened pathogens or their antigens are put into the body
2) the antigens stimulate an immune response by lymphocytes which produce antibodies
3) memory cells are produced that give long-term immunity

Question 18

how does vaccination help control the spread of disease

Answer 18

• ensures herd immunity, few places where pathogen can breed.
• ensuring the entire vaccinated population remains at a high level, very few new host organisms where that pathogens can multiply

Question 19

what is passive immunity

Answer 19

short- term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk
- memory cells re not produced in passive immunity

Question 20

why is breast milk important

Answer 20

it helps the very young to fight off infections until there are older and stronger

Question 21

what is cholera

Answer 21

cholera is a disease caused by bacterium which is transmitted in contaminated water
- cholera bacterium produces a toxin that causes secretion of chloride ions into the small intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration and loss of ion from the blood