Cells and tissues of the immune system

Question 1

From which system do the cells of the immune system differentiate from?

Answer 1

Haematopoietic system

Question 2

TRUE or FALSE

White blood cells are mostly found in the blood

Answer 2

FALSE

WBCs use the bloodstream to go from point A to point B

The bloodstream is not where they are normally found

Question 3

What is the haematopoietic system?

Answer 3

All the cells come from the same stem cells

In the bone marrow

Very few hundred stem cells produce all the different immune cells

Question 4

What are the criteria of the immune system?

Answer 4

Dynamic and responsive - 10^10 granulocytes are formed per day and 10^9 lymphocytes are produced per day

Movable - constantly moving

Renewable - dynamic and short lived nature means it needs to be renewable

Large - lots of energy expended on maintaining the immune system

Question 5

What are the main compartments of the immune system?

Answer 5

Blood

Immunological organs

Lymphatics

Non-immunological organs

Bone marrow

Question 6

What is the immune cell distribution like throughout the body?

Answer 6

Entirely immunological and composed entirely of immunologically relevant cells

But all organs have some immunological aspect to them, which in organs where there is a greater chance of infection

The body can divert immune cells to organs when needed

Question 7

What allows the diversion of immune cells from immonological to non-immunological organs?

Answer 7

A parallel system connects the two

Carries immunological information and cells to the non-immunological organs to carry out an appropriate response

Question 8

Which non-immunological organs have greater immunological components?

Answer 8

Skin

GI

Question 9

What are the two key immunological organs?

Answer 9

Lymph nodes

Spleen

Question 10

What is the function of lymph nodes?

Answer 10

Serve as focal points of immunological responses around the body

Question 11

What is the function of the spleen?

Answer 11

Serves the blood

White blood cells coordinate immunological responses in the blood

Question 12

What are the lymph nodes and spleen examples of?

Answer 12

Secondary lymphoid tissues

Question 13

What are the primary lymphoid tissues?

Answer 13

Thymus and bone marrow

Question 14

What are the functions of the primary lymphoid organs?

Answer 14

Development of immune cells

Do not perform important immunological responses

Question 15

What are the functions of the secondary lymphoid tissues?

Answer 15

Where the immune response is orchestrated

Question 16

TRUE or FALSE

The two branches of the immune system are linked and cannot work without the other

Answer 16

TRUE

Question 17

TRUE or FALSE

Defects in either system of the immune response is not compatible with life

Answer 17

TRUE

Question 18

What are the three main types of innate cells?

Answer 18

Granulocytes

Macrophages

Dendritic cells

Question 19

What are the three cells of the borderland group between innate and adaptive immune cells?

Answer 19

Innate lymphoid cells

NK cells

NK T cells

Question 20

What are the three main types of Granulocytes?

Answer 20

Neutrophils

Eosinophils

Basophils

Question 21

Describe the function of granulocytes

Answer 21

First line of defence

Prevent infection through phagocytosis and killing

Important in allergic reactions

Contain a large number of granules

Granules contain toxic molecules and enzymes that kill bacteria

Recruited from blood to tissue during inflammation

Question 22

Are granulocytes short or long-lived cells?

Answer 22

Short lived

If no entry of bacteria = die

Question 23

What is the major circulating white blood cell in the body?

Answer 23

Neutrophils

70-80%

Question 24

Describe the function of macrophages

Answer 24

Phagocytosis

Tissue resident cells, with each tissue containing their own resident macrophages

Important sensors of infection

Principle immunological role is to kill bacteria that withstand neutrophil bactericidial properties

Question 25

TRUE or FALSE The main role of macrophages are immunological

Answer 25

FALSE Major role is not immunological, but rather a scavenger of dying cellular debris

Question 26

Are macrophages a first or second line of defense?

Answer 26

Second line of defense

Question 27

What is an example of a tissue resident macrophage?

Answer 27

Kuppffer cells Liver

Question 28

Are macrophages short or long lived?

Answer 28

Long lived Months

Question 29

Describe the function of lymphocytes

Answer 29

Small Represent 25% of WBC, but only 2% of total blood Major cells of the adaptive immune system Constantly recirculating between tissues and the blood

Question 30

TRUE or FALSE T and B cell populations are histologically indistringuishable

Answer 30

TRUE whilst in the blood and no infection. When an infection develops however, their volume increase and produce granules, become motile When they respond to antigen they no longer look the same Various stages of differentiation - resting lymphocyte, activated lymphocyte, plasma cell

Question 31

Are lymphocytes short or long lived?

Answer 31

Long lived Divide very slowly until needed

Question 32

What are lymph nodes?

Answer 32

Sacs of lymphatics containing a system of tubing connecting them to other lymph nodes and the blood

Question 33

What do the efferent lymphatics represent?

Answer 33

Exit From lymph nodes to the blood

Question 34

What do the afferent lymphatics represent?

Answer 34

From blood to lymph node

Question 35

Why does the lymph node need a blood supply?

Answer 35

Many cells entering the lymph node come from the blood

Question 36

Why does the lymph node have to been structured?

Answer 36

Helps efficient drainage and cellular communication Provides time for the immune system to decide how to react

Question 37

What are the parts of the lymph node?

Answer 37

Separate T and B cell areas Reticular meshwork Dendritic cell networks

Question 38

What are the three main roles of a lymph node?

Answer 38

Maintain local microenvironment for different cells to develop Reticular meshwork traps antigen to allow time for deciding how to react Allows cells to interact since blood is a poor space for communication due to clotting consequences

Question 39

What are dendritic cells?

Answer 39

Found in all tissues of the body Act as a interface between innate and adaptive immunity

Question 40

Describe how dendritic cells present antigen

Answer 40

Long processes catch antigens Sample antigens from the environment Carry them to lymph nodes if they think its foreign Wait for T cells to come and sample the surface, where antigens are presented

Question 41

Describe how lymphocytes constantly check for pathogens

Answer 41

Lymphocytes re-circulate through the blood and lymphatics Every now and then they go to lymph node and check if there is something in the lymph node they can react to Once responded, they can live in the blood for years and wait for more of the same antigen Next time you meet antigen, they can leave the blood directly into the tissue without having to enter the lymph node Here they can kill the antigen and go into the blood or signal for more lymphocytes to be produced

Question 42

Describe how granulocytes and macrophages are different in the way they look for pathogens

Answer 42

Granulocytes only check non-immunological organs Macrophages check both immunological and non-immunological organs