Cells and organs of the immune system Flashcards
Name the two types of leukocyte
lymphocytes, which are responsible for recognising foreign material
phagocytes whose main function is to internalise it and destroy it.
Name the two types of lymphoid tissues and describe their location?
The primary lymphoid tissues are the bone marrow and thymus, where the cells of the immune system are first produced and trained.
The secondary lymphoid tissues include the spleen, lymph nodes and mucosa-associated lymphoid tissues (MALT) including Peyers patches
Describe how leukocytes are transported around the body?
lymphocytes leave the primary lymphoid
they enter the blood and colonise the secondary lymphoid tissues by crossing specialised endothelial cells that line the blood vessels in these
tissues
from there they can return to the blood via the lymphatics
the lymphatic system is a network of blind-ended vessels that permeate all tissues except the brain
lymphocytes which have been activated following an encounter with antigen migrate more frequently through other tissues of the body but can return from there to the secondary lymphoid tissues via
lymphatics
lymphocytes can also migrate into and out of the spleen
mononuclear phagocytes migrate from the primary lymphoid tissues to blood and then to other tissues, but can also recirculate via the lymphatics
the other principal type of phagocyte, the neutrophil, makes a one-way journey from the bone marrow to the tissues
Name the two phases of the immune response?
The recognition of the infectious agent
The effector phase of the response, when the immune system aims to eliminate the infection, or at least contain it and minimise the damage it
causes.
Name the main routes of infection?
Skin
Mucous membranes
Gut cavity
Specific (affecting the point of entry such as gonorrhoea) and systemic infection pathways (spread throughout the body
Give two examples of mucosal associated lymphoid tissue (MALT)?
Tonsils in the throat
Adenoids in the nose
List the types of lymphoid associated tissues in the body and their function?
MALT - mucosal associated lymphoid tissue
BALT - bronchus associated lymphoid tissue
Payers patches in the gut
Lymphoid tissues are also present in the genitourinary tract and eyes
They contain lymphocytes and are the first contact that pathogens have with the immune system
During the effector stage of the immune response, what is released by the sub mucosal lymphocytes?
Immunoglobin A (IgA) which is secreted into the mucous
What is lymph?
Lymph is a fluid which is derived from tissues and carries cells and foreign materials to the lymph nodes via the lymphatic system
It enters the bloodstream via one of two lymphatic ducts
What do lymph nodes contain?
Leukocytes - troops of the immune system
What is the function of the spleen?
The spleen is a lymphoid organ and it’s role is to remove infectious agents circulating in the blood
The spleen is just behind the stomach
It contains two types of tissue…
White pulp - lymphatic tissue
Red pulp - destroys aging red blood cells
Where do the cells of the immune system originate from?
All immune cells originate from stem cells in the bone marrow
Lymphoid stem cells give rise to all lymphocytes
Myeloid stem cells give rise to all the other leukocytes. (
A third stem cell type in bone marrow gives rise to red blood cells and platelets, which are not part of the immune system.
Even cells of the thymus, the other primary
lymphoid organ, migrate there initially from bone marrow.
What is the CD system?
The cluster of differentiation - CD
This is an identification system used with immune system cells and acts by the binding of antibodies to surface receptors which are specific to certain types of cell, therefore allowing their identification
What is clonal selection?
When a lymphocyte binds to an antigen it is stimulated to divide and produce clones of itself which are able to deal with the pathogen/antigen present.
