Tissue Fluid + Formation Flashcards
What is tissue fluid?
Tissue fluid is a watery liquid that contains glucose, amino acids, fatty acids, ions in solution and oxygen
What is the function of tissue fluid?
Tissue fluid supplies substances (oxygen, glucose) to tissues and removes waste minerals (carbon dioxide) from them
How does tissue fluid facilitate exchange between blood and cells?
It baths all the body’s cells, acting as the immediate environment where materials are exchanged
How is tissue fluid formed?
Tissue fluid is formed from blood plasma, which is regulated by homeostatic systems
How does tissue fluid help maintain a stable environment for cells?
Since blood plasma composition is controlled by homeostasis, tissue fluid provides a mostly constant environment for the cell it surrounds
How is tissue fluid formed?
Tissue fluid is formed when hydrostatic pressure at the arterial end of the capillaries forces fluid out of the blood plasma
What creates the hydrostatic pressure in capillaries?
Pumping of the heart generates hydrostatic pressure, which pushes blood along arteries, arterioles and then capillaries
What forces oppose the outward movement of tissue fluid?
1/ Hydrostatic pressure of the tissue fluid outside the capillaries resists further fluid loss
2/ Lower water potential of the blood (due to plasma proteins) draws water back into capillaries by osmosis
Why do only small molecules leave the capillaries during tissue fluid formation?
The pressure is only strong enough to force out small molecules; cells and plasma proteins remain in the blood because they are too large to pass through capillary membranes
What is ultrafiltration?
Ultrafiltration is the process where small molecules are forced out of capillaries under pressure, while larger molecules remain in the blood
How is tissue fluid returned to the circulatory system?
Most tissue fluid returns directly to the blood plasma via capillaries after exchanging metabolic materials with cells
How does hydrostatic pressure help tissue fluid return to capillaries?
The loss of tissue fluid from capillaries lowers their hydrostatic pressure, making it lower than the pressure in the surrounding tissue fluid. This forces tissue fluid back into the capillaries
How does osmosis contribute to the return of tissue fluid?
Plasma proteins lower the water potential of the blood, so water moves back into capillaries from tissue fluid down a water potential gradient
How does the composition of tissue fluid change before returning to the blood?
It loses oxygen and nutrients to cells but gains carbon dioxide and waste materials
How does the structure of lymphatic vessels compare to capillaries?
Lymphatic vessels resemble capillaries but have dead ends and gradually merge into larger vessels that drain into veins near the heart
How does lymph return to the bloodstream?
Lymph drains into the bloodstream through two ducts that join veins close to the heart
What happens to the tissue fluid that does not return to capillaries?
It is carried back via the lymphatic system, a network of vessels that drain excess fluid back into the bloodstream
How is lymph moved through the lymphatic system?
Lymph is moved by the hydrostatic pressure of the tissue fluid leaving the capillaries and the contraction of the body’s muscles, which squeeze the lymph vessels
What prevents backflow in the lymphatic system?
Valves in the lymph vessels ensure that lymph moves in one direction - towards the heart
