Discuss how homeostasis of the body depends on the continual movement of the blood, interstitial fluid, and lymph. Include an explanation of fluid balance and what can happen if fluids are out of balance

What will be an ideal response?

Most of the body's cells are embedded in tissues and thus are stationary. They cannot move around to get oxygen and nutrients, nor can they move away from wastes they produce (carbon dioxide, heat, and other metabolic wastes) or from changes in pH. Instead, three fluids interact to ensure the health of these stationary cells: blood, interstitial fluid, and lymph.
Blood carries oxygen from the lungs and nutrients from the digestive tract to the tissue cells. Interstitial fluid (surrounding the cells) acts as a medium for exchange between the blood and the cells: Oxygen and nutrients travel from the blood through interstitial fluid into the cells; carbon dioxide, heat, other metabolic wastes, and products made by the cells such as enzymes and hormones move from the cells into the interstitial fluid. Some of the interstitial fluid, and the substances it contains, enters the blood that is carried away from the cells while some interstitial fluid continually drains into lymphatic vessels and becomes lymph. After being filtered through lymph nodes, lymph returns to the blood and becomes part of it again.
Fluid balance means that various parts of the body have the amount of water and solutes (dissolved particles) they need to function properly. If not enough interstitial fluid drains into lymphatic vessels, an excessive amount of interstitial fluid can accumulate, resulting in edema. If there is not enough fluid in the blood, hypotension can result.