What are lymph nodes?
Lymph nodes are small capsulated lymphoid tissue pieces which are present along the passage of lymphatics.
What are the structures that form lymph nodes?
- A surrounding capsule made up of collagen dense connective tissue.
- Trabeculae(Partitions within the lymph node)
- Cortex(Outer part)
- The inner part of the lymph node is called Inner Cortex(Para-cortex).
- The innermost area of the lymph node is called Medulla.
What is the route of lymph flow through a lymph node?
1) Afferent Lymphatic vessel
2) Sub-capsular sinuse
3) Trabecular sinuse
4) Medullary sinuse
5) Efferent Lymphatic vessel
What are lymphatic sinuses?
They are inter-connecting and inter-communicating lymphatic channels within the substance of the lymph node.
What are medullary sinuses?
These sinuses make some random network of intra-communicating channels as they make their way-down.
Medullary sinuses drain into which lymph vessel?
The efferent lymph vessel(Lymphatics).
What are the cells found in the outer cortex?
Follicular Dendritic Cells
What are the cells found in the inner cortex?
What are the cells found in the medulla?
What are the function of macrophages in a lymph node?
- They engulf and breakdown bacteria into phagolysosome.
- In the acidic endosome it fuse the bacteria with the antigen class II molecule for immune response.
What is the function of Dendritic cells in a lymph node?
They are antigen presenting cells that process antigen material and present it on their cell surface to the T cells.
What is the function of Follicular Dendritic Cells in lymph nodes?
They act as antibody reception cells that hold antibody together with antigen.
Where are Follicular Dendritic Cells specifically located?
In lymph follicles of the B cells.
What is the function of Reticular cells in lymph nodes?
They provide structural support.
Note: They produce and maintain a thin network of fibres that are a framework for most lymphoid organs.
What is the consequence of having 3L of interstitial fluid in the interstitial spaces?
Edema would occur, causing tissue damage and eventually death.
Lymphatic vessels are lined with what type of cells?
Lymphatic Endothelial Cells(LEC)
What is the importance of Lymphatic Endothelial Cells concerning transport?
It helps transport antigens and cells from tissues to lymph node.
Lymphatic vessels become more leaky with _____.
The blood vessels connected with High Endothelial Venules(HEV) are lined with ________ _______________ _______ .
Blood Endothelial Cells
What does the Follicular Dendritic Cells (FDC) in lymph nodes support?
- They support high affinity antibody production.
- Capture of immune complexes.
What are the functions of Fibroblastic Reticular Cells (FRC) in lymph node?
- FRCs wrap collagen fibers to form conduits that direct antigen and chemokine trafficking in the lymph node.
- It also produces Interleukin-7 (IL-7) and help maintain naive T cells.
What is the purpose of Fibroblastic Reticular Cells forming reticular networks?
So as to direct T cells and Dendritic cells trafficking in the lymph node.
Where are B cells located in lymph nodes?
They are mostly located in follicles.
Antigens in afferent lymph vessels that enters the subcapsular sinus must gain access from whom?
From follicular B lymphocytes.
What happens when B cells are stimulated?
It proliferates and convert into plasma cells responsible for producing antibodies.
Where does T cell mature?
In the Thymus.
The inner cortex is __________ dependent.
What is the importance of T cells?
They are important for cell mediated immunity and the activation of immune cells to fight infection(viral infection).
Which cell eliminate intra-cellular organism?
T cells with the help of T-cytotoxic cells.
The inner cortex swells up because of what?
T-cell which are proliferating.
What is the function of plasma cells in lymph nodes?
They act as the first line of defense against invading microorganisms.(For e.g viruses and parasites.)
How do small arteries enter the lymph nodes?
Through the hilum.
What is the function of post capillary venules in the inner cortex?
They catch lymphocytes by hooking them with their receptors and then forcing them to pass in between the endothelial cells to exit out.
Lymph nodes acts as biological _________.