Immune System Flashcards
What are the 3 cells of the immune system
lymphocytes, antigen presenting cells (APCs) and reticular cells
What is the function of reticular cells?
to create a connective tissue scaffolding to house lymphocytes.
synthesize collagen to produce reticular fibers.
where are APCs found?
in lymphoid organs and other tissues/areas that are regularly exposed to antigens
What are APCs derived from?
Bone marrow
What are some types of antigen presenting cells?
Dendritic cells, langerhans cells, macrophages, B-cells
What is the purpose of a primary lymphoid tissue?
a site of maturation for lymphocytes
What are the primary lymphoid tissues?
thymus, bursa of fabricus, ilocecal peyer’s patches, bone marrow
What is the purpose of a secondary lymphoid tissue?
site of function for lymphocytes
What are the secondary lymphoid tissues?
tonsils, spleen, lymph nodes, peyer’s patches
What will you find in the cortex of the thymus?
T-cells at various stages of maturation
What will you find in the medulla of the thymus?
fully mature T-cells
How do you differentiate the thymus cortex from the medulla on a slide?
the medulla is lighter staining and has fewer lymphocytes
Explain the blood flow to the cortex of the thymus
continuous capillaries penetrate the cortex - prevents immature lymphocytes from entering circulation
Explain the blood flow to the thymus medulla
the epithelial reticular cells coving blood vessels is incomplete to the venules at the cortico-medullary juntion are permeable to macromolecules and cells. (sinusoidal capillaries) Allows mature lymphocytes to enter circulation.
common features of secondary lymphoid tissues:
presence of nodules/follicles
sites for immunologic surveillance
localizes the immune responses
what do nodules/follicles primarily consist of?
B-cells
Function of a lymph nodule
collect antigen moving through lymph in the body and filters it before returning it to the bloodstream. Trap antigens and present thm to B or T-cells
function of the spleen
traps antigen circulating in the blood
What is MALT
mucosa associated lymphatic tissue (i.e. tonsils)
function of MALTs
traps antigens attempting to enter the body through the mucosa and skin
How can you tell if a lymph nodule is active?
Presence of germinal center (within the mantle or corona)
If within a lymph node, it will enlarge
In what species will you find a hemal node?
ruminants
functions of lymph nodes
mechanical and phagocytic filtration of lymph
proliferation of lymphocytes
immune response: cellular or humoral response
Explain the flow of lymph through a lymph node
enters through afferent vessels which empty into the subscapular sinus. Lymph flows into the cortical sinuses, then flows into the medullary sinuses. Lymph leaves via efferent vessels at the hilus
Lymph nodes are comprised of ?
lymph nodules
What cells will you find in the mantle (or corona) of the lymph nodule?
primarily B-cells
What cells will you find in the paracortical zone of the lymph nodule
primarily T-cells
What is the function of the arrangement of the reticular cells in the medullary sinuses?
slows lymph flow, facilitating antigen-cell interactions and phagocytosis
How does lymph flow differ in a tonsil or MALT from flow through a lymph node?
MALT have no afferent vessels. only efferent
What is the largest lymphatic organ in the body?
the spleen
What are the two pulp types found in the spleen
red pulp and white pulp
What does the red pulp of the spleen consist of
primarily RBCs
(vascular system)
what does the white pulp of the spleen consist of?
immune system, WBCs
in the PALs - T-cells
in the lymphoid follicles - B-cells
in the marginal zone - plasma cells and macrophages
What color stain does the red pulp pick up? why?
pink! acidophilic due to the presence of RBCs
How do you identify white pulp?
White pulp (parenchyma) has a central artery surrounded by T-cells (very basophilic) and splenic nodules (active B-cells)
Function of the white pulp in the spleen?
defense - humoral and cellular immunity
function of red pulp of the spleen
filtration and storage of blood
What are hemal lymph nodes?
like small spleens (kinda between a lymph node and a spleen) in ruminants only
Explain the general flow of lymph
- APC with antigen migrate to lymph node (enter node via affernt lymph)
- lymphocytes interact with APC and proliferate
- Lymphocytes exit node with efferent lymph
- Lymph enters blood at anterior vena cava/subclavian vein
- Lymphocytes exit blood and enter inflammed tissue
Antigen vs antibody
Antigens allow your body to create a defense against future invaders. Antibodies circulate in your body once created to identify, attack, and destroy the same type of antigens if they enter the body again
another name for antibody?
immunoglobin
what type of cells produce Abs?
plasma cells
