Body Fluid Regulation
Start with the big picture
Total body water is distributed mainly between intracellular fluid and extracellular fluid; the latter includes plasma and interstitial fluid. Osmolarity describes solute concentration, while the kidneys help regulate fluid volume by adjusting urine output. Hormonal signals coordinate this response: ADH promotes water reabsorption when osmolarity rises or volume falls, aldosterone supports sodium reabsorption and water conservation, and ANP promotes sodium and water loss in response to atrial stretch. Hypothalamic osmoreceptors detect osmolarity, while baroreceptors monitor volume and pressure. Together, these sensors and hormonal pathways help explain the body’s responses to water deficit, blood loss, and water overload.
What you'll learn
- Describe the main body fluid compartments and their relative proportions.
- Explain osmolarity and its role in fluid homeostasis.
- Summarize how ADH, aldosterone, and ANP affect fluid regulation.
- Distinguish the roles of osmoreceptors and baroreceptors.
- Relate dehydration, hemorrhage, and water overload to homeostatic responses.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
