Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
5 Cards in this Set
- Front
- Back
|
Tissue fluid |
Liquid that surrounds the cells and allows for transport, by diffusion, between the blood and cells. Capillary walls are partially permeable so hydrostatic pressure and osmosis form tissue fluid from blood plasma. |
|
|
Arterial end of capillaries with respect to tissue fluid |
Net out (higher hydrostatic pressure and water potential inside capillary)
Hydrostatic pressure (of blood from heart contractions) forces fluid out of the capillaries through tiny gaps in walls. This is called ultrafiltration and forces water and other small molecules out of the blood plasma (dissolved gases and nutrients) but larger plasma proteins and cells are too big to move. Some hydrostatic pressure from the tissue fluid resists the movement of liquid so forces it back into the capillaries. |
|
|
Veinous end of capillaries with respect to tissue fluid |
Net in (osmosis) A net loss of water from capillaries to the tissue fluid due to hydrostatic pressure whilst plasma proteins cannot move results in a more negative water potential inside the capillaries so water enters. |
|
|
Net fluid movement with respect to tissue fluid |
Net figure found by subtracting water potential effects from hydrostatic pressure. Changes along capillary as hydrostatic pressure is greater in the capillary at the arterial end but as tissue fluid is lost it decreases and water potential is lower inside the capillary. |
|
|
Lymph |
Some tissue fluid is eventually reabsorbed but overall there is slightly more out than in. The excess must be collected to avoid tissue swelling so is drained into the lymphatic system where it becomes known as lymph. Lymph is moved by the hydrostatic pressure of tissue fluid leaving the capillaries and the contraction of body muscles towards the heart, where it drains back into the circulatory system via two ducts that join veins close to the heart. Lymphatic vessels are a network throughout the body that are like capillaries but with dead ends. |
