7.6: Tissue fluid formation Flashcards
What is Tissue Fluid
A watery liquid that contains glucose, amino acids, fatty acids, ions in solution and oxygen
What does tissue fluid supply
Tissues with the substances it contains, and in return received Carbon Dioxide and other waste materials
What is Tissue Fluid formed from
Blood plasma
What is Tissue Fluid the immediate environment of
All Cells in the body. It provides a mostly constant environment
How is tissue fluid formed
When the heart pumps, blood passes along arteries, then narrower arterioles, then narrower capillaries.
This produces hydrostratic pressure at the arterial end of the capillaries
The hydrostatic pressure causes tissue fluid to move out of the blood plasma
What factors counteract the outward pressure within capillaries
- Hydrostatic pressure of the tissue fluid outside the capillaries which resists outward liquid movement
- The lower water potential of the blood, due to plasma proteins, which causes water to move back into the blood within the capillaries
What do these factors combine to form
The combined effect of all these forces creates an overall pressure that pushes tissue fluid out of the capillaries at the arterial end
What is a result of this pressure formation
The pressure is only enough to force small molecules out of the capillaries, leaving all cells and proteins in the blood as these are too large.
What is this pressure called
Ultrafiltration
How is tissue fluid returned to the circulatory system
- The loss of the tissue fluid from the capillaries reduces the hydrostatic pressure within them
- As a result, when blood reaches the venous end, its hydrostatic pressure is lower than that of the tissue fluid outside it
- Therefore tissue fluid is forced back into the capillaries by the higher hydrostatic pressure outside them. Plasma also lost water and still contains proteins.
