Phagocytes

Question 1

What is phagocytosis?

Answer 1

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

Question 2

What is a phagocyte?

Answer 2

Cels which can ingest particles from the surrounding

Question 3

What is an antigen?

Answer 3

A molecule that stimulates an immune response

Question 4

What is the immune response?

Answer 4

A specific response to a pathogen which involves lymphocytes and antibodies

Question 5

What are types of non-specific defences?

Answer 5

Blood clotting, inflammation, wound repair and phagocytes

Question 6

What is the purpose of blood clotting?

Answer 6

To seal off wound

Question 7

What is the purpose of inflammation?

Answer 7

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

Question 8

What is the purpose of wound repair?

Answer 8

To regenerate tissues using collagen

Question 9

What are types of phagocytes?

Answer 9

Neutrophils and macrophages

Question 10

What are the goals of secondary defences?

Answer 10

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

Question 11

What are the 3 types of phagocytes?

Answer 11

Monocytes, macrophages and granulocytes

Question 12

What are monocytes?

Answer 12

Not mature phagocytes

Question 13

What are macrophages?

Answer 13

They are free or fixed

Question 14

What are granulocytes?

Answer 14

Basophils, neutrophils and eosinophils

Question 15

Where are neutrophils made?

Answer 15

In bone marrow

Question 16

How do neutrophils move?

Answer 16

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

Question 17

What is the lifespan of neutrophils?

Answer 17

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

Question 18

What is the structure of neutrophils?

Answer 18

They have lysosomes and a very effective cytoskeleton

Question 19

What can neutrophils respond to?

Answer 19

Histamine and cytokines

Question 20

How are neutrophils attracted?

Answer 20

Damaged and infected cells release histamine and capillaries are leakier

Question 21

What is the result of histamines?

Answer 21

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

Question 22

Where are macrophages made?

Answer 22

In bone marrow

Question 23

How do macrophages move?

Answer 23

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

Question 24

What is the lifespan of macrophages?

Answer 24

They are long lived

Question 25

What is the function of macrophages?

Answer 25

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

Question 26

Where are dendritic cells found?

Answer 26

Tissues close to edge of body such as skin and gut

Question 27

What is the function of dendritic cells?

Answer 27

They ingest pathogens and migrate to lymph nodes to display antigen

Question 28

What are the stages of phagocytosis?

Answer 28

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

Question 29

What is the process of antigen presentation?

Answer 29

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

Question 30

What is MHC?

Answer 30

A cell surface protein used by vertebrates to recognise foreign molecules

Question 31

How does MHC work?

Answer 31

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

Question 32

How many classes of MHC are there?

Answer 32

2

Question 33

How do cytokines work?

Answer 33

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

Question 34

What is the effect of antigens?

Answer 34

They stimulate an immune response

Question 35

What happens in response to antigens?

Answer 35

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

Question 36

How are glycoproteins produced?

Answer 36

By lymphocytes

Question 37

What is the purpose of glycoproteins?

Answer 37

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

Question 38

What is the shape antibodies?

Answer 38

Y shape

Question 39

What is the structure of antibodies or immunoglobulins ?

Answer 39

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

Question 40

What is the same across all antibodies of a class?

Answer 40

The constant region

Question 41

What are actions of antibodies?

Answer 41

Opsonins, agglutination and anti-toxin preparation

Question 42

What do opsonins do?

Answer 42

They coat pathogen binding sites and tag them

Question 43

What is the effect of opsonins?

Answer 43

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

Question 44

What is agglutination?

Answer 44

Large antibodies bind to many pathogens

Question 45

What is the effect of agglutination?

Answer 45

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

Question 46

What is anti-toxin preparation?

Answer 46

Soluble toxins released by bacteria are precipitated out of solution

Question 47

What is the effect of anti-toxin preparation?

Answer 47

Can be phagocytosed more easily