Natural Barriers, Innate Defences & Parasite-Host Relationship

Question 1

What is complement?

Answer 1

a group of serum proteins that float around in the blood - inactive state.

Question 2

how many mechanisms are there for complement?

Answer 2

1. classic (adaptive immune system)
2. alternative (innate immune system)
3. lectin (innate immune system)

Question 3

What happens in classic?

Answer 3

c1q bind to pathogen or antibodies on pathogen surface.

Question 4

what happens in alternative?

Answer 4

spontaneous hydrolysis of c3, deposits c3 convertase on pathogen surface.

Question 5

What happens in lectin?

Answer 5

mbl binds to carbohydrates on pathogen surface.

Question 6

What are the results of the complement?

Answer 6

• phagocytes follow the c3a chemokine gradient leading to inflammation and recruitment of immune cells to the site of infection.
• phagocytes recognise the c3b on the pathogen and phagocytose the infection
• completion of the complement cascade leads to formation of the mac, causing the membrane to disintegrate and the cell to lyse.

Question 7

What are phagocytic cells?

Answer 7

• macrophages - engulf pathogens and dead cell remains.

- neutrophils - ingests microorganisms and destroys them (most abundant WBC)

Question 8

Natural killer cells?

Answer 8

• attack body’s cells that have been infected (not foreign cells)
• also attack potential cancer cells.
• kills by binding and releasing perforin - makes holes in the membranes

Question 9

Features of fever?

Answer 9

• accompanies inflammation.
• temperature above 37, sweating hyperventilation
• allows for more rapid recovery

Question 10

how does fever allow for rapid recovery?

Answer 10

• higher temperature speeds up important immune reactions.

- pathogens like a strict temp range - higher temps make unfavourable growth conditions

Question 11

What is the major role of normal flora?

Answer 11

• prevents colonisation of pathogens.
• takes up space and nutrients of pathogens.
• produces fatty acids that make the environment unfavourable for other bacteria.

Question 12

what does active refer to?

Answer 12

actually have the disease.

Question 13

what does incubatory refer to?

Answer 13

have the disease but not yet showing symptoms.

Question 14

what does convalescent refer to?

Answer 14

recovered from disease but can still spread.

Question 15

what does chronic refer to?

Answer 15

harbours pathogens for long periods of time. generally NO symptoms but can still spread the disease.