Tissue fluid Flashcards
What is tissue fluid?
The fluid that surrounds cells in tissues, and contains substances filtered out of blood to bring oxygen and nutrients to cells
What makes up tissue fluid?
Made from small molecules that leave the blood plasma such as water and oxygen and nutrients and small proteins
To be given to cells
But also waste products of cells that are drained out
What is the function of tissue fluid?
Cells take in nutrients, oxygen and water from tissue fluid
then releases metabolic waste back into it (eg CO2) for capillaries to take in to drain out waste
Arteriole end of a capillary: tissue fluid formation
Hydrostatic pressure in blood in capillaries is high due to contraction of arterioles
So water and dissolved substances is forced out of capillary through fenestrations
What is the hydrostatic pressure in arteriole end caused by?
Ventricle contracting and sending blood from arteries to arterioles
Smaller osmosis of water into capillary
Due to higher water potential in the tissue fluid than capillary thus osmosis from high water potential to low water potential
Arteriole end net movement
Overall, water and nutrients and oxygen out of capillary into tissues
What proteins remain in the Arteriole end of capillary?
Plasma and large proteins remain in capillaries
Venule end of capillary
Net movement of water containing dissolved waste substances into capillary via osmosis
Down a water potential gradient into blood from tissue fluid
What is the osmotic movement of water into capillary at the Venule end caused by?
Lower water potential in capillary than in fluid due to a high conc of plasma proteins remaining in capillary
So osmosis of water into the capillary
Smaller hydrostatic pressure at Venule end of capillary
Caused by lower hydrostatic pressure as the pressure begins to decrease thus small movement into capillary
+ friction
What happens to excess tissue fluid that does not get absorbed back into blood by osmosis?
Is drained into lymphatic system as lymph (liquid)
Eventually drains back into blood
Does tissue fluid return to blood at venule end of capillary?
No, water in the tissue fluid does
Why is the water potential at venule end of capillary lower than in tissue fluid?
Water left capillary at arteriole end
Plasma proteins remain in capillary = more concentrated = lower water potential
Why is the net flow of water out of capillary at arteriole end?
Hydrostatic pressure build up that forces water out of capillary surpasses water potential gradient of water inti blood from tissue fluid
