Lympathic System Flashcards
What is the Lymphatic system made up of?
Fluid (Lymph), vessels (Lymphatics), cells (lymphocytes, dendritic cells and macrophages), tissues and organs
How is the lymph in the lymphatics forced back up the body?
Skeletal muscles contract putting pressure on the vessels, forcing the fluid back up. Larger Lymphatics also have smooth muscle in their walls which can contract. Value ensure flor of the lymph in one direction only. Also pressure changes in the Thorax.
Where does the Lymph fluid pass back into the blood?
At the Jugular and subclavian veins.
What is the lymph fluid made up of? (4)
Proteins, excess interstitial fluid, lymphocytes and fats which have been absorbed in the villi of the small intestine
What are the organs involved in the Lymphatic system? (3)
Lymph nodes, thymus and the spleen
What is Mucosal Associated Lymphatic Tissue? (MALT)
MALT are bundles of Lymphatic cells called Lymphatic nodules located within the mucous membranes lining the gastrointestinal, respiratory, reproductive and urinary tracts. They contain lymphocytes and macrophages. It a a diffuse system.
What are the sub divisions of MALT? (2)
GALT (gut associated lymphoid tissue) which lines the small intestines. BALT (bronchus associated lymphoid tissue).
Give 3 examples of Lymphatic nodules
Tonsils, Peyer’s Patches and vermiform Appendix.
Where are follicular dendritic cells located?
In the germinal centres of the lymph nodes
What are the functions of the Lymph nodes?
They filter the lymph fluid and remove pathogens and abnormalities.
Why is the lymph fluid returned to the blood system via veins?
As the veins have a lower pressure so minimises the impact of the blood pressure.
What are the 3 main roles of the Lymphatic system?
Forms part of the immune system, absorbs fats from the digestive system and absorbs excess interstitial fluid (3 litres a day).
Why are there Peyer’s patches located in the ileum of the small intestine?
In case the valve between the colon and the ileum stops working as the colon is full of bacteria which could then enter the ileum.
What are lymphatic nodules?
Oval shaped concentrations of Lymphatic tissue. Large aggregations of these nodules are found in the appendix and make up the tonsils and Peyer’s Patches.
What is a Lymphatic organ?
Lymphatic tissue enclosed by a connective tissue capsule.
Why is the Lymph fluid protein rich?
Because proteins cannot be directly reabsorbed by blood vessels.
What type of cells form the lymph capillaries?
Endothelial cells
Where on a lymph node is the draining vein, feeding artery and efferent Lymphatic vessel located?
Hilum
What do the outer cortex of lymph nodes contain?
Densely packed lymphocytes arranged in masses called Lymphatic nodules. The nodules contain germinal centres, where the lymphocytes are produced.
Through what vessels does the lymph fluid enter the lymph nodes?
Afferent Lymphatic vessels
What are the 3 types of tonsils?
Palatine, Lingual and Pharyngeal (Adenoid)
What is the function of the tonsils?
The tonsils are aggregations of Lymphatic nodules embedded in a mucous membrane which produce antibodies and lymphocytes.
What are the functions of the spleen?
Haemopoietic functions: Filters the blood, removes old red blood cells by phagocytosis, retrieves iron from haemoglobin,
Immune function: produces B cells which develop into plasma cells. Contains professional antigen presenting cells.
Where is the thymus located?
In the super mediastrium (above the heart)
What is the role of the thymus?
Where the bone marrow derived stem cells mature in T lymphocytes (thymol cell education).
What is the cause of enlarged lymph nodes and what is this called?
Lymphadenopathy is caused when the germinal centres fill with lymphocytes during an infection which causes the swelling.
What causes Lymph Oedema?
If your Lymphatics aren’t working properly or if your born without them.
What is cellulitis?
An infection beneath the skin caused by static fluid
What are professional antigen presenting cells and where are they found?
They are found in lymph nodes. They present antigens in their cell surface membrane to activate T lymphocytes. Examples include B cells and macrophages.
What type of responses can B and T cells produce?
An inflammatory response, which is mediated by neutrophils and macrophages. A specific immune response (via the humoral and cell mediated responses ).
How do lymphocytes enter and leave a Lymph node
They enter via the feeding artery and leave via the efferent Lymphatic vessel
What organs take over the functions of a spleen following a splenectomy?
The liver and bone marrow
What is the role of follicular dendritic cells?
Cause a rapid increase in the number of B cells (particularly B memory cells). Trap and present antigens opsonised by complement or antibodies, which the B cells must bind to, to become memory cells otherwise they go through apoptosis.
