Phagocytes Flashcards

1
Q

What is phagocytosis?

A

A form of endocytosis where large particles (e.g. cell debris) are taken up into vesicles and are fused with a lysosome so degraded products are recycled if useful

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2
Q

What is a phagocyte?

A

Cels which can ingest particles from the surrounding

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3
Q

What is an antigen?

A

A molecule that stimulates an immune response

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4
Q

What is the immune response?

A

A specific response to a pathogen which involves lymphocytes and antibodies

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5
Q

What are types of non-specific defences?

A

Blood clotting, inflammation, wound repair and phagocytes

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6
Q

What is the purpose of blood clotting?

A

To seal off wound

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7
Q

What is the purpose of inflammation?

A

Histamine causes cells to release cytokines messenger molecules that increase inflammation and fever

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8
Q

What is the purpose of wound repair?

A

To regenerate tissues using collagen

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9
Q

What are types of phagocytes?

A

Neutrophils and macrophages

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10
Q

What are the goals of secondary defences?

A

Neutralise any toxins produced by pathogens, prevent pathogen multiplying, kill pathogen and remove any remains of pathogen

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11
Q

What are the 3 types of phagocytes?

A

Monocytes, macrophages and granulocytes

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12
Q

What are monocytes?

A

Not mature phagocytes

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13
Q

What are macrophages?

A

They are free or fixed

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14
Q

What are granulocytes?

A

Basophils, neutrophils and eosinophils

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15
Q

Where are neutrophils made?

A

In bone marrow

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16
Q

How do neutrophils move?

A

They travel in the blood and squeeze through tissues through capillaries so can rapidly exit into tissues

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17
Q

What is the lifespan of neutrophils?

A

They are short lived and are released in large names when an infection occurs and form pus when they die

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18
Q

What is the structure of neutrophils?

A

They have lysosomes and a very effective cytoskeleton

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19
Q

What can neutrophils respond to?

A

Histamine and cytokines

20
Q

How are neutrophils attracted?

A

Damaged and infected cells release histamine and capillaries are leakier

21
Q

What is the result of histamines?

A

More fluid causes swelling and more tissue fluid which washes pathogens into lymph nodes where macrophages wait

22
Q

Where are macrophages made?

A

In bone marrow

23
Q

How do macrophages move?

A

They are stationary or mobile so can travel in monocytes or settle in tissues (especially lymph nodes) and develop into macrophages

24
Q

What is the lifespan of macrophages?

A

They are long lived

25
Q

What is the function of macrophages?

A

They engulfed foreign pathogens and present antigens to lymphocytes (T-cells)

26
Q

Where are dendritic cells found?

A

Tissues close to edge of body such as skin and gut

27
Q

What is the function of dendritic cells?

A

They ingest pathogens and migrate to lymph nodes to display antigen

28
Q

What are the stages of phagocytosis?

A
  1. Pathogens release chemicals that attract phagocyte.
  2. Phagocytes recognise non-self glycoproteins on surface of pathogens
  3. Binds to pathogen
    4.
29
Q

What is the process of antigen presentation?

A
  1. Digested pathogen fragments combine with MHC surface glycoproteins
  2. MHC-antigen complex displayed on surface of macrophages
  3. Now antigen presenting cell to T cells
30
Q

What is MHC?

A

A cell surface protein used by vertebrates to recognise foreign molecules

31
Q

How does MHC work?

A

It binds to peptide fragments from pathogens and displays for recognition by T cell

32
Q

How many classes of MHC are there?

A

2

33
Q

How do cytokines work?

A

The attraction more phagocytes to attract more WBC to increase body heat

34
Q

What is the effect of antigens?

A

They stimulate an immune response

35
Q

What happens in response to antigens?

A

The formation of antibodies and is recognised by the immune system as foreign to the body, a toxin is released by the pathogen and chemical markers on the outer membrane of pathogen

36
Q

How are glycoproteins produced?

A

By lymphocytes

37
Q

What is the purpose of glycoproteins?

A

They are released in response to an infection and identity and neutralise antigens

38
Q

What is the shape antibodies?

A

Y shape

39
Q

What is the structure of antibodies or immunoglobulins ?

A

Variable region which has different amino acids which form different shapes and has a specific shape which is complementary to 1 antigen

40
Q

What is the same across all antibodies of a class?

A

The constant region

41
Q

What are actions of antibodies?

A

Opsonins, agglutination and anti-toxin preparation

42
Q

What do opsonins do?

A

They coat pathogen binding sites and tag them

43
Q

What is the effect of opsonins?

A

The pathogen is unable to infect cell and phagocytes recognise antibodies and engulf pathogens

44
Q

What is agglutination?

A

Large antibodies bind to many pathogens

45
Q

What is the effect of agglutination?

A

Clump is too large to enter cells and is more likely to be phagocytosed

46
Q

What is anti-toxin preparation?

A

Soluble toxins released by bacteria are precipitated out of solution

47
Q

What is the effect of anti-toxin preparation?

A

Can be phagocytosed more easily