Cells and tissues of the immune system Flashcards
From which system do the cells of the immune system differentiate from?
Haematopoietic system
TRUE or FALSE
White blood cells are mostly found in the blood
FALSE
WBCs use the bloodstream to go from point A to point B
The bloodstream is not where they are normally found
What is the haematopoietic system?
All the cells come from the same stem cells
In the bone marrow
Very few hundred stem cells produce all the different immune cells
What are the criteria of the immune system?
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
What are the main compartments of the immune system?
Blood
Immunological organs
Lymphatics
Non-immunological organs
Bone marrow
What is the immune cell distribution like throughout the body?
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
What allows the diversion of immune cells from immonological to non-immunological organs?
A parallel system connects the two
Carries immunological information and cells to the non-immunological organs to carry out an appropriate response
Which non-immunological organs have greater immunological components?
Skin
GI
What are the two key immunological organs?
Lymph nodes
Spleen
What is the function of lymph nodes?
Serve as focal points of immunological responses around the body
What is the function of the spleen?
Serves the blood
White blood cells coordinate immunological responses in the blood
What are the lymph nodes and spleen examples of?
Secondary lymphoid tissues
What are the primary lymphoid tissues?
Thymus and bone marrow
What are the functions of the primary lymphoid organs?
Development of immune cells
Do not perform important immunological responses
What are the functions of the secondary lymphoid tissues?
Where the immune response is orchestrated
TRUE or FALSE
The two branches of the immune system are linked and cannot work without the other
TRUE
TRUE or FALSE
Defects in either system of the immune response is not compatible with life
TRUE
What are the three main types of innate cells?
Granulocytes
Macrophages
Dendritic cells
What are the three cells of the borderland group between innate and adaptive immune cells?
Innate lymphoid cells
NK cells
NK T cells
What are the three main types of Granulocytes?
Neutrophils
Eosinophils
Basophils
Describe the function of granulocytes
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
Are granulocytes short or long-lived cells?
Short lived
If no entry of bacteria = die
What is the major circulating white blood cell in the body?
Neutrophils
70-80%
Describe the function of macrophages
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
TRUE or FALSE
The main role of macrophages are immunological
FALSE
Major role is not immunological, but rather a scavenger of dying cellular debris
Are macrophages a first or second line of defense?
Second line of defense
What is an example of a tissue resident macrophage?
Kuppffer cells
Liver
Are macrophages short or long lived?
Long lived
Months
Describe the function of lymphocytes
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
TRUE or FALSE
T and B cell populations are histologically indistringuishable
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
Are lymphocytes short or long lived?
Long lived
Divide very slowly until needed
What are lymph nodes?
Sacs of lymphatics containing a system of tubing connecting them to other lymph nodes and the blood
What do the efferent lymphatics represent?
Exit
From lymph nodes to the blood
What do the afferent lymphatics represent?
From blood to lymph node
Why does the lymph node need a blood supply?
Many cells entering the lymph node come from the blood
Why does the lymph node have to been structured?
Helps efficient drainage and cellular communication
Provides time for the immune system to decide how to react
What are the parts of the lymph node?
Separate T and B cell areas
Reticular meshwork
Dendritic cell networks
What are the three main roles of a lymph node?
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
What are dendritic cells?
Found in all tissues of the body
Act as a interface between innate and adaptive immunity
Describe how dendritic cells present antigen
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
Describe how lymphocytes constantly check for pathogens
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
Describe how granulocytes and macrophages are different in the way they look for pathogens
Granulocytes only check non-immunological organs
Macrophages check both immunological and non-immunological organs
