Chapter 29, Problem 1O

Summary Introduction

To review:

The function of fluid volume and compartments within the body and the role of major electrolytes in maintaining homeostasis.

Concept introduction:

Fluids in the body are divided into compartments. Fluids within the cell contain dissolved solutes, mostly in the form of electrolytes. The fluids outside the cell play a greater role in transportation of nutrients. Fluid and electrolyte balance are the major factors that help in maintaining homeostasis. This ensures an equal intake and release of fluids.

Explanation of Solution

Fluids in the body are distributed into two main compartments namely intracellular fluid (ICF) and extracellular fluid (ECF). ICF is within the cells, and it dissolves electrolytes and other solutes. ECF is present outside the cells. They help in the transport of nutrients and waste products. ECF can be an interstitial fluid that surrounds the cells or intravascular fluid that refers to the blood in the circulatory system.

The volume of fluids is very important to maintain an essential balance of the body. If more water is lost from the body than it is gained, it results in a condition called dehydration. There are 3 main types of dehydration namely hypertonic, hypotonic, and isotonic. Hypertonic dehydration results when the amount of water lost is greater than the amount of sodium lost. This increases the concentration of solutes outside the cell and causes the cell to shrink by loss of fluid to outside. Hypotonic dehydration occurs when the amount of sodium lost is greater than the amount of water lost. This increases the solute concentration inside the cells and as a result, the solvent is pulled into the cells. Isotonic dehydration occurs due to a decrease in ECF volume by loss of both sodium and water.

The important electrolytes include sodium, potassium, magnesium, calcium, phosphate, chloride, and bicarbonate. Potassium is the major electrolyte in the intracellular fluid, whereas sodium and chloride are the main electrolytes in extracellular fluid. Potassium plays major roles in nerve impulse transmission, contraction of muscles, and heartbeat regulation. Sodium is the most important electrolyte that helps in maintaining acid–base balance, osmotic pressure, and controlling water distribution. Clotting of blood, enzyme reactions, and other homeostatic mechanisms are also controlled by the balancing of electrolytes.

Conclusion

An increase or decrease in the amount of fluids can result in improper functioning of body mechanisms. Thus, fluid balance should be maintained in the body. This is carried out with the help of several electrolytes and solutes.