Lymphatic system Flashcards
(9 cards)
what is an lymphatic system?
it is an extensive network of vessels.
what do the vessels in the lymphatic system do?
they carry a fluid called lymph.
what does the fluid lymph contain?
list 2
1) leucocytes (especially lymphocytes)
2) fluid from the intestines containing proteins and lipids.
what is the largest organ in the lymphatic system?
spleen
what are the properties of the spleen?
list 3
1) they contain an emergency supply of erythrocytes, leucocytes and thrombocytes.
2) there are also sac-like structures called lymph nodes.
3) they filter out and trap bacteria, viruses, cancer cells and other unwanted substances to ensure they are eliminated from the body.
what is tissue fluid?
it is a watery liquid that surrounds cells.
what is the function of a tissue liquid?
it is to bathe cells and help substance exchange between blood and cells occur.
how is tissue fluid made?
list 3
1) a capillary bed is a concentration of capillaries that supply blood to a particular organ or area.
2) as blood travels down a capillary two pressures act:
- hydrostatic pressure — the pressure fluids (such as blood) exert ——-> this pushes out of the capillary.
- osmotic pressure — the pressure of water ——-> this pushes into the capillary.
3) at the arterial end of the capillary hydrostatic pressure is higher than osmotic pressure:
- this forces water and small molecules through the capillary walls.
- this forms tissue fluid between the capillary cells and the cells of the body organs or areas.
how is lymph made?
list 3
1) as blood moves along the capillary the pressure falls: this is due to friction with the walls and lower blood volume.
2) at the venous end of the capillary the hydrostatic pressure has dropped so much that it is lower than the osmotic pressure: this means most of the water from the tissue fluid moves back into the capillaries.
3) the remainder of the fluid is transported back to the blood through the lymph vessels: so becomes lymph.
