diseases and immunity (topic 10)

Question 1

what is a pathogen

Answer 1

A disease-causing agent such as a virus or a bacterium.

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

what are the two ways a pathogen can be transmitted

Answer 3

directly and indirectly

Question 4

describe pathogen transmission through direct contact

Answer 4

through body fluids such as blood and other bodily fluids

Question 5

describe pathogen transmission through indirect contact

Answer 5

such as from the air, through water or food, contaminated surfaces or animals.

Question 6

what is meant by bodys first line of defence

Answer 6

The body’s initial defence against disease: non-specific physical or mechnical barriers that prevent pathogens from entering the body.

Question 7

what is meant by bodies second line of defence

Answer 7

The immune system is the second line of defence if a pathogen passes the first line of defence, enters the body and causes an infection.

Question 8

examples and explanations of first line of defence

Answer 8

mucus- present in the respiratory tract traps dust and pathogens. (chemical barrier)
nose hair- The hairs of the nose trap dust particles and pathogens. (mechanical barrier)
stomach acid- Acid secreted in the stomach kills microorganisms in food and water. (chemical barrier)
skin- acts as a barrier, prevents entry of pathogen (mechanical barrier)

Question 9

examples and explanations of second line of defence

Answer 9

Once a pathogen gains entry to the body, the immune system detects and destroys pathogens.
white blood cells:
phagocytes: surround and engulf pathogen in phagocytosis
lymphocytes: prodcue antibodies proteins that attach to pathogens and either kills or marks for destruction

Question 10

what are some methods to decrease spread of diseases

Answer 10

a clean water supply
good personal hygiene
hygienic food preparation
proper waste disposal
treatment of sewage.

Question 11

what is active immunity

Answer 11

Immunity that develops in response to a pathogen and involves the activation of memory cells.

Question 12

what is an antigen

Answer 12

the part of a pathogen which is unique to each type of pathogen, has a complementary shape to the antibody in the body

Question 13

what are antibodies

Answer 13

proteins produced by lymphocytes, have a complementary shape to antigens, bind
to antigens leading to direct destruction
of pathogens or marking of pathogens for
destruction by phagocytes

Question 14

how is active immunity gained

Answer 14

after infection of the pathogen, or after vaccination

Question 15

what are memory cells

Answer 15

A cell that forms from a lymphocyte as the immune system responds to an infection. It remains in the bloodstream and can recognise pathogens that infect after a first infection. It then differentiates to form antibody-producing lymphocytes that mount a secondary response, (bigger antibody concentration and faster response)

Question 16

outline the process of vacciantion

Answer 16

1. vaccine made of weakened or dead pathogen, injected into body
   2.the antigens stimulate an immune response by lymphocytes which produce antibodies
   3.memory cells also produced which means if host infected again with same pathogen, secondary immune response is mounted, destorys pathogen much faster

Question 17

what is the role of vaccination

Answer 17

controlling the spread of diseases

Question 18

explain passive immunity

Answer 18

a short-term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk

Question 19

what are advantages and disadvantages of active immunity

Answer 19

-lasts a very long time, memory cells can respond to pathogen for years or maybe for rest of host life (produces memory cells)
-slow response

Question 20

what are advantages and disadvantages of passive immunity

Answer 20

-fast response, immediate
-protection only lasts weeks/ month (no memory cells produced)

Question 21

why is breast feeding important

Answer 21

because of the development of passive immunity in infants
it contains antibodies that are passed to the child. These antibodies help very young babies to fight off infections until they are older and stronger, and able to receive their first childhood vaccines.

Question 22

what is cholera

Answer 22

Bacterial infection caused by water or food contaminated with the bacterium Vibrio cholerae. (bacterium which is transmitted in contaminated water)

Question 23

what does the cholera bacterium do?

Answer 23

once bacteria in body, fo towards small intestine, inside small intestine secrete cholera toxin, which causes the intestinal cells to secrete chloride ions into the lumen of the intestine, high concentration of chloride ions causes osmotic movement of large amounts of water into the intestinal lumen
causes diarrhoea and severe dehydration and loss of ions from the blood, can lead to death

Question 24

how is diarrhoa treatd

Answer 24

oral rehydration therapy, replace lost water, drink mixture of sugar/ salts/ ions