Ch 15 extra

Question 1

Describe the functions of the lymphatic system.

Answer 1

• to collect and return tissue fluid to circulation.
• this prevents oedema
• Lymph nodes are a major site of lymphocyte productions.
• The system transports fats, fatty acids and glycerol.

Question 2

Describe the immune system in terms of phagocytosis.

Answer 2

• Neutrophils carry out phagocytosis.
• there is receptor protein on the cell wall of a neutrophil.
• the neutrophil moves towards the pathogen.
• Bacteria sticks to the CSM.
• The neutrophil membrane infolds and them flows around and engulfs the pathogen.
• The cell membrane then pinches of and forms a vacuole in neutrophil.
• The enzymes digest the pathogen.

Question 3

Describe the immune system in terms of vaccination.

Answer 3

• A vaccine contains weakened or dead pathogens.
• or poisonous toxins produced by them.
• The antigens are still present on the weakened pathogens
• Causes lymphocytes to produce antibodies
• Memory cells release the correct antibodies when the real pathogen enters the body
• The person is then immune to the disease

Question 4

Describe the immune system in terms of tissue rejection (dis ‘n lang een hierdie)

Answer 4

• Transplanted organs may be a different tissue type, which creates a chance of rejection
• The donor and recipient must be carefully matched, so that the organ has the same tissue type and blood type. Usually from a close relative
• Rejection means that lymphocytes recognise the new organ as “foreign” and release antibodies to attack the organ
• The patient is given immunosuppressant drugs to kill lymphocytes
• This causes loss of protection from other infectious diseases, and the patient is placed into isolation
• Genetic engineering can be used to clone or produce organs
• Shortage of organs for transplantation creates a black market
• Transplanting an organ is very expensive

Question 5

Describe active immunity

Answer 5

• Long term protection
• Produce own antibodies
• Body has memory cells which can produce these antibodies
• This explains getting chicken pox only once

Question 6

Describe passive immunity

Answer 6

• Temporary protection against a disease
• Given ready-made antibodies
• Given antibodies eventually disappear
• No memory cells to produce antibodies

Question 7

Describe natural active immunity

Answer 7

• Catching and recovering from a disease such as chicken pox causes the body to produce long lasting antibodies
• Memory cells “remember” the antigen and can release the correct antibody when the pathogen enters the body again

Question 8

Describe artificial active immunity.

Answer 8

• You are immunised against diseases such as polio, meningitis or TB
• Receiving an injection of a weakened strain of a disease.
• The vaccine is injected into you, and youproduce your own antibodies in response.

Question 8

Describe natural passive immunity.

Answer 8

• immunity acquired by babies from their mothers.
• Antibodies are present in mother’s blood from previous infections and immunisations.
• babies getting antibodies when feeding on breast milk.
• antibodies cross the placenta during pregnancy to the foetus.
• Memory cells do not cross the placenta, so immunity is temporary.

Question 9

Describe artificial passive immunity.

Answer 9

• Receiving an injection of a serum containing antibodies.
• Horses are injected with small doses of snake venom.
• The antibodies produced by the horses are extracted.
• Snake bite victim can be injected with these antibodies to give them temporary immunity and time for its own immune system to respond to the venom.

Question 10

Describe the transmission and symptoms of malaria, explain the reasons why the immune system may fail to eliminate malaria from the body and its importance as a major disease in many countries.

Answer 10

study page 293 the Fact about malaria.

Question 11

Describe the role of the female Anopheles mosquito in transmission of Plasmodium.

Answer 11

• Mosquitoes stab and sucks human blood.
• If the victim has malaria, parasites enter the mosquito with the blood.
• When biting a uninfected person, the female anopheles mosquito injects saliva into the person ( contains anticoagulant) into the person to prevent blood from clotting.
• the saliva contains parasites which enter the uninfected person.

Question 12

study cycle on page 294

Answer 12

Hi……This is Dog.

Question 13

Name the Symptoms of malaria.

Answer 13

• Fever ( hot spells )
• Shivering ( cold spells )
• Sweating and shaking
• Headaches
• Muscle pains
• Nausea ( NOT vomiting )
• Extreme tiredness.

Question 14

Why does malaria cause extreme tiredness?

Answer 14

• One has fewer red blood cells.
• This results in less haemoglobin to transport oxygen.
• Burst red blood cells block capillaries.
• Less oxygen is available to respiration.
• Less energy will be release.

Question 15

Describe the transmission of malaria in step form

Answer 15

1. Female Anopheles mosquito sucks infected blood
2. Plasmodium sp enters the mosquito’s stomach
3. Cell division produces thousands of plasmodium sp parasites
4. Plasmodium sp parasites invade the mosquito’s salivary glands
5. Infected mosquito sucks blood from another person
6. Plasmodium sp parasites enters the human bloodstream and then the liver
7. Plasmodium sp parasites leave the liver and enter red blood cells
8. Red blood cells burst, causing symptoms of malaria

Question 16

Why does the immune system fail to eliminate malaria from the body?

Answer 16

• The parasite constantly outmanoeuvres the immune system
• Starts by hiding in the red blood cells
• Immune system ignore red blood cells as the spleen filters out defective red blood cells
• To avoid the filter, the parasites eject about 60 protein hooks, which attaches to the inner wall of a blood vessel.
• Plasmodium sp can become resistant to prophylactic drugs
• Plasmodium sp has many surface antigens which causes hufe antigenic variation

Question 17

Name ways in which malaria can be prevented

Answer 17

• Mosquito nets
• Take anti-malarial drugs, which prevents reproduction of the parasite in humans
• Mosquito repellent cream and spray
• Cover exposed areas of the body in the evening

Question 18

Describe how mosquito numbers can be reduced in order to prevent malaria

Answer 18

• Drainage of stagnant water
• Oil or petrol can be sprayed on the surface of water to suffocate larvae and pupae and to prevent the laying of eggs
• Insecticide spray like DDT
• Close open standing water
• Introduce fish and thereby biological control to water sources
• Release sterile male mosquitos into the environment

Question 19

Look at the distribution map on page 297. Now state the temperature under which the plasmodium parasite can not complete its life cycle

Answer 19

Below 20 degrees