Immunity

Question 1

State 3 differences between artificial active and artificial passive immunity

Answer 1

AA : AP
Injection with dead/ weakened pathogens : injection with antibody for specific antigens

Stimulates immune system to produce own antibody : does not stimulate immune system

Provides long term protection : provides short term protection

Question 2

Explain inflammation

4 P

Answer 2

• 2nd line of defence
• Redness occurs as blood cappilaries dilate to allow more blood flow near the skin surface
• Swelling occurs due to histamine which makes blood cap, more permeable to phagocytes
• Hotness due to more blood flow to increase metabollic rate to aid in phagocytosis
• Pain so that individual is more cautious at the injured area

Question 3

What is the role of skin in the defence mechanism?

Answer 3

• Skin is thick and tough which makes it difficult for pathogens to penetrate across
• sweat glands on skin secretes sweat containing lysozyme
• Constant shedding of dead skin cells makes it difficult for bacterium growth
• sebum contains oil and acid which can prevent bacterium growth

Question 4

Define pathogens

Answer 4

microorganisms that causes diseases

Question 5

define antigen

Answer 5

Proteins attached to surface of pathogen which triggers immune response in body
- binded by antibodies so that phagocytes can engulf them easily

Question 6

State 2 types of phagocytes

Answer 6

monocyte

neutrophill

Question 7

explain phagocytosis process

Answer 7

the pseudopodium extends and envelops the bacterium –> phagosome is formed –> phagosome fuses with lysosome to form phagolysosome –> lysozyme is secreted to digest bacterium –> digested bacterium is secreted out of phagocyte

Question 8

What are memory cells

Answer 8

produced by B lymphocyte.

are stimulated to produce antibodies rapidly when a same pathogen infects.

Question 9

Explain opsonisation

Answer 9

Antibodies bind to antigens and act as marker to be easily recognised by phagocytes

Question 10

Explain precipitation

Answer 10

Antibodies react with dissolved antigens to form a precipitate so that it can be easily destroyed by phagocytes.

Question 11

Which antibody action involves toxins

Answer 11

Neutralisation

Question 12

State 1 advantage of artificial passive immunity

Answer 12

Immediate protection is provided

Question 13

Why does a person who suffered from chicken pox is not likely to suffer the disease anymore?

Answer 13

He has achieved natural active immunity. The first time he had chicken pox, B lymphocyte in his immune system is stimulated to produce memory cells. When he is infected with chicken pox the second time, the memory cells are stimulated to produce antibodies rapidly to overcome the pathogens.

Question 14

Why does vaccine require 2nd dose?

Answer 14

During the 1st dose, concentration of antibody is not above the level of immunity yet. Booster dose is given to increase concentration of antibodies above level of immunity.

Question 15

What does HIV stand for?

Answer 15

HUman Immunodefeciency virus

Question 16

What does AIDS stand for?

Answer 16

Acquired Immunodefficiency Syndrome

Question 17

How does HIV affect an individual

Answer 17

It weakens the immune system making the individual easily infected by other diseases.

Question 18

Why does someone who has HIV not necessarily have AIDS?

Answer 18

• An individual only develop AIDS if her/his immune system weakens
• An individual will stay healthy is his/her immune system stays strong and not affected by the virus

Question 19

How does HIV paralyse the immune system (BONUS)

Answer 19

• HIV attacks T lymphocyte –> T lymphocyte becomes a host for the HIV –> HIV builds its DNA genetic materials –> viral DNA enters nucleus of T lymphocyte, combines and become part of the T lymphocyte’s DNA –> In T-lymphocyte, HIV virus can replicate to produce new HIV populations which attacks other T lymphocytes