Non-specific animal defences against pathogens - destroying it Flashcards Preview

AS Biology (Dr Sams) > Non-specific animal defences against pathogens - destroying it > Flashcards

Flashcards in Non-specific animal defences against pathogens - destroying it Deck (9)
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1
Q

How is a fever triggered?

A

cytokines stimulate the hypothalamus to reset and causes the temperature to go up

the hypothalamus is responsible for maintaining body temperature

2
Q

Why is a fever useful?

A

high temperatures inhibit pathogen reproduction

the immune systems works faster at higher temperatures

3
Q

What are phagocytes? What are the two types?

A

phagocytes are specialised WBC that engulf and destroy pathogens

the two main types are neutrophils and macrophages

they build up at the site of an infection

pus consists of dead neutrophils and pathogens

4
Q

How do phagocytes recognise a pathogen?

A

pathogens produce chemicals that attract phagocytes

they recognise non-self proteins on the pathogen - not specifically a pathogen, but a cell or organisms that is non-self

5
Q

How does the phagocyte destroy the pathogen?

A

it engulfs the pathogen and encloses it in a vacuole called a phagosome

the phagosome combines with a lysosome to form a phagolysosome

enzymes from the lysosome digest and destroy the pathogen

6
Q

What is the difference between phagocytosis in macrophages and neutrophils?

A

macrophages undergo a more complex process

when it has digested the pathogen, it combines antigens from the pathogen surface membrane with special glycoproteins in the cytoplasm called the major histrocompatibility complex (MHC)

the MHC moves these pathogen antigens to the macrophage’s own surface membrane, becoming an antigen-presenting cell (APC)

these antigens now stimulate other cells involved in the specific immune sysstem response

7
Q

What does the number of different types of lymphocytes in a blood smear?

A

indicates whether it is a specific response or not

8
Q

What are cytokines? How are they produced?

A

phagocytes that have engulfed a pathogen produce them

they act as cell-signalling molecules, informing other pathogens to move to the site of infection

also they increase the body temperature and stimulate the specific immune system

9
Q

What are opsonins?

A

chemicals that bind to pathogens and tag them so they can be more easily recognised by pathogens

phagocytes have receptors on their cell membreanes that bind to common opsonins and the phagocyte then engulfs the pathogen

e.g. immunoglobuling G and M have the strongest effect