The Lymphoid System Flashcards
What is the lymphatic system made up of?
lymphatic vessels and lymph nodes located along their course
What are lymphatic channels?
blind ended vessels that permit passive unidirectional flow (valves) of lymphatic fluid
What are the main functions of the lymphatic system?
FLUID HOMEOSTASIS:
returns fluid from extracellular connective tissue to the circulation which prevents accumulation of fluid in tissues (oedema)
IMMUNE FUNCTION:
movement of fluid means cells and molecules in fluid pass through the lymph nodes and interact with cells of the immune system
Describe what lymph nodes are?
small (up to 2.5 cm) oval bodies located along the course of lymphatic vessels and often in groups
Precursor lymphocytes are formed from ______
haemopoietic stem cells
Where do precursor lymphocytes mature?
primary lymphoid organs:
B cells in the bone marrow
T cells in the thymus
What are the secondary lymphoid organs?
lymph nodes, Peyer’s patches, spleen, mucosal tissue in certain places
Explain where B cells are found in the lymph node and what this means?
B cells are found in the follicles of the lymph nodes so a predominant B cell response results in follicular hyperplasia
Explain where T cells are found in the lymph node and what this means?
T cells are found in the inter follicular area so a predominant T cell response results in expansion of the inter follicular area
What is the role of the spleen?
Responsible for filtering the blood, phagocytosis debris and generating an immune response
The spleen consists of?
red pulp and white pulp
What does red pulp consist of?
consists of sinuses lined by endothelial macrophages and cords (spaces)
What does white pulp consist of?
similar structure to that of lymphoid follicles
Explain what happens in the spleen?
Blood enters via the splenic artery and is delivered to the red and white pulp
During the flow the blood is ‘skimmed’ with leucocytes and plasma preferentially passing to the white pulp
Some red cells pass rapidly through into the venous system while others are help up in the red pulp (older damaged RBCs)
