lymphatic system Flashcards
what is the role of the lymphatic system?
- act as transport system for APCs to secondary lymphoid tissue (lymph nodes) for antigen recognition
- location for clonal selection and initiates adaptive immune response
- production of leukocytes including lymphocytes
- removal of fluid from tissues around the body
- provides a location for lymphocytes to mature
- provides a site for clonal selection and expansion, and subsequent storage of specific memory cells
- returns interstitial fluid that has been lost from cells or blood vessels to the circulatory system
- absorbs and transports fatty acids and fats that have been digested
what is the lymphatic system?
a large network of vessels throughout the body through which lymph flow. Forms an important component of both the circulatory and immune systems
what does the lymphatic system consist of?
capillaries, lymph, lymphatic vessels and primary and secondary lymphoid organs
what are primary lymphoid organs?
components of the lymphatic system that are responsible for the production and maturation of lymphocytes
This includes:
- bone marrow
- thymus
What is the significance of bone marrow in the lymphatic system?
Bone marrow is where B and T lymphocytes (important in the adaptive immune response) originate. B lymphocyte mature in the bone marrow
What is the significance of the Thymus in the lymphatic system?
immature T lymphocytes travel to the thymus where they mature before ending up in lymph nodes
what are secondary lymphoid organs?
components of the lymphatic system responsible for the maintenance of mature lymphocytes and the activation of the adaptive immune response.
This includes lymph nodes and spleen. This is where B and T cells are activated
how do lymphocytes become activated?
lymphocytes become activated when they encounter antigens specific to their receptors. They are able to proliferate, creating clones of the initial lymphocyte with the specific receptor for the antigen. This is a process called clonal selection and expansion
how do the lymphatic system and the cardiovascular system work together?
- small lymph capillaries interact with blood capillaries in the interstitial spaces in tissues
- lymph vessels collect fluid that leaks from blood capillaries and returns it to the cardiovascular system
- as lymph is being transported, it passes through lymph nodes which contain specialised white blood cells
what are lymphocytes?
A type of white blood cell that is present in large numbers in lymphoid tissue and circulating in blood and lymph
This includes: B lymphocytes, T lymphocytes and NK cells
what are lymphatic capillaries?
collection of interstitial fluid from from spaces between cells begin here
- close-ended tubes where interstitial fluid that is bathing the tissue enters through mini valves of the capillary
- interstitial fluid could contain: immune cells, pathogens, fragments of pathogens
- once in the lymphatic capillary the fluid is known as lymph
function of lymphatic vessels
They follow a similar pattern to the venous part of the vascular system. Collect interstitial fluid to filter and return to the blood stream.
- lymphatic vessels bring lymph to the lymph nodes and return lymph to the blood through a lymphatic duct into the vein located near the clavicle/collarbone
- the movement of the lymph is largely due to the extended pressure applied to the lymph vessels through muscle contractions
- one way valves ensure that flow of lymph occurs in single direction
what is the function of lymph nodes?
lymph nodes are a major site of filtration for the identification of non-self antigens to trigger the adaptive immune response
- site where lymph is filtered
- any pathogen or pathogens would encounter phagocytes and lymphocytes
- the phagocytes can present pathogen’s antigens to a T-helper lymphocyte
- APCs can also be present in lymph that has come from a site of infection to present the non-self antigens to a helper T-lymphocyte
what is the lymphatic system’s role in the inflammatory response?
The lymphatic vessels present in the tissues affected by injury drain the fluid from tissues and join it with the lymphatic system. This fluid contains pathogens from site of injury as well as APCs that have consumes pathogens
what is the function of lymphatic surveillance?
lymph is delivered to lymph nodes and drains through clusters of B and T cells. Here, APC and pathogens with lymph are most likely to meet with a lymphocyte that has a matching antigen binding site and stimulate a process called clonal expansion. Lymph drains away from lymph nodes and efferent lymphatic vessel. This lymph contains antibodies and cytotoxic T-cells which may have been created if an adaptive immune response was initiated
