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Question about tissue fluid and blood plasma?

How do substances from the blood plasma enter tissue fluid from the capillaries?
Original post by hannah.dykes
How do substances from the blood plasma enter tissue fluid from the capillaries?


In the circulatory system, blood flows from the heart, through the arteries, and into capillaries that surround all cells. When blood reaches the capillaries, a portion of blood plasma (the liquid portion of the blood) seeps out of the capillaries and into the space surrounding cells. That plasma is then known as tissue fluid. Tissue fluid consists of water plus dissolved molecules that are small enough to fit through the small openings in capillaries.

Hope that helps :smile:
The key thing to remember is that this happens by diffusion.

Blood plasma is forced out of capillaries due to high pressures at the arterial end (the end where the arteries connect) - it diffuses out.

Then, when it becomes tissue fluid, it bathes the body cells. Oxygen and glucose diffuse into the body cells by the tissue fluid and waste and urea diffuse out.

The tissue fluid seeps back into the capillary at lower pressures (the vein end of the capillary).
Reply 3
Thank You!! :smile:

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