11.17: Hist of Lymph Flashcards
What are the primary lymphoid organs?
- Bone marrow
- Thymus
* *Both contain immature lymphoid cells
What are the secondary lymphoid organs?
- Lymphnodes
- Spleen
- MALT: “Mucosal associated lymphoid tissue”
* **All contain mature lymphoid cells
What happens to T cells in the thymus?
- T cells formed in marrow then move to thymus to mature
- Learn self tolerance: respond to foreign antigens and not the body
What type of cells predominate in cortex and medulla of Thymus?
Medulla: Epithelial cells
Cortex: T cells, move to medulla as they mature
Where are hassall’s corpuscles found?
- Medulla of thymus
- Thought to be degenerated epithelial cells
What happens to thymus as we age?
- Majority of tissue is replaced with fat
Main function of lymph node?
- Capture, process, and destroy antigens that are found in lymph
What is lymph?
- Fluid that is an ultrafiltrate of blood
- Predominately made of water
- Travels to nodes in lymphatic vessels
What layer of node are follicles contained in?
Cortex
What is found just under the capsule of the node?
- Subcapsular sinus
- This is where lymph enters the node then moves to cortical sinus
Function of primary and secondary follicles?
Primary: contain mature B cells, can respond to antigens but are naive as haven’t had chance to
Secondary: What we call primary follicle once B cell has been activated to create germinal center
What happens when B cell is exposed to antigen?
Becomes activated and moves to center of follicle to proliferate forming a Germinal center
What is a germinal center?
Site of B cell proliferation
What is the mantel zone?
Darker area on outside of follicle
Primary function of spleen?
- Site of destruction of old RBCs
- Capturing and processing antigens
