Lymphatics Flashcards
Describe the structure of capillaries:
Thinner walls Numerous and highly branched Narrow diameters Narrow lumen Spaces between endothelium
What is the reason for capillaries having thin walls?
Decreases diffusion distance for gases
What is the reason for capillaries being numerous and highly branched?
Large surface area for exchange of gases
What is the reason for capillaries having spaces between endothelium?
So white blood cells can pass through
What is the reason for capillaries having a narrow lumen?
So red blood cells are squashed against the side of the capillary, decreasing the diffusion distance for gases
How much interstitial fluid is generated daily from capillary filtration?
3 litres
What are the constituent parts of the lymphatic system?
Conducting system
Lymphoid tissue
What is the role of lymphatic capillaries?
To collect interstitial fluid created from capillary flitration
What is the structure of a lymphatic capillary?
Blind-ended, bulbous tubes lined with endothelial cells
What is the function of uni-directional valves in the lymph conducting systems?
They prevent the backflow of lymph
What causes lymph to move through the conducting system?
Contraction of smooth muscle
What happens to lymph at the lymph nodes?
Bacteria and foreign material is removed by phagocytosis
What do lymph capillaries merge into?
Collecting lymph tubes
Describe the structure of lymph collecting tubes:
Smooth muscle and Uni-directional valves
Where is lymph collected from and by what is it collected?
Collected by lymph capillaries from the interstitial space
Describe the passage of lymph through the lymphatic system:
Collected in lymphatic capillary Merge into collecting vessel Afferent lymphatics take to lymph node Through thoracic duct Into subclavian vein
What is meant by the term afferent lymphatic?
Uni-directional
Where does lymph re-enter the circulatory system?
Subclavian vein
What is the role of the lymphatic conducting system?
Carries lymph to the nodes and back into the bloodstream
Lymph nodes are considered as what type of lymphoid tissue?
Secondary
The thymus and bone marrow are considered as what type of lymphoid tissue?
Primary
What is oedema?
Swelling in the tissues due to excess fluid in the interstitial space
What is kwashiorkor?
A malnourished person does not receive enough protein, therefore, osmotic potential is decreased and less water is pulled into blood capillary. This excess tissue fluid causes a ‘puffed’ belly effect
What can cause oedema?
When the rate of capillary filtration is greater than the rate of lymphatic drainage
(Therefore, very fast filtration or dysfunctional drainage)
What are secondary lymphoid organs of the body?
Lymph nodes, Payers patches, Tonsils and Adenoids, maintain mature naïve lymphocytes and initiate acquired immune response, sites of lymphatic activation
Why might capillary filtration be increased?
An osmotic pressure difference and the capillary hydrostatic pressure
What is elephantiasis?
Where nematode worms are present in the lymphatic vessels causing lymph to build up
What are primary lymphoid organs of the body?
Thymus and Bone marrow, involved in production and early selection of lymphocytes, generate lymphocytes from immature cells
