PHGY 210 Lecture Notes - Lecture 34: Aldosterone, Natriuresis, Baroreceptor

• School: McGill University
• Department: Physiology
• Course: PHGY 210
• Professor: Erik Cook

Document Summary

Sodium (na) and water are important components of body fluids. Total-body balance of na and water has to be maintained to sustain normal blood pressure and life. Both sodium and water are freely filtered but ~99% is reabsorbed (no secretion) Majority of sodium and water reabsorption (~2/3) occurs in proximal tubule. But major hormonal control of reabsorption occurs on dct and cd. Basic renal processes for sodium and water: sodium reabsorption is active process occurring in all tubular segments (except descending thin limb of henle s loop) Requires atp: water reabsorption is by diffusion and is dependent upon sodium reabsorption. Sodium is major extracellular solute, thus changes in total body sodium result in similar changes in extracellular fluid volume. Total body sodium is sensed as intravascular filling by baroreceptors in cardiovascular system. Plasma concentration of sodium is not marker for total body sodium. Pna only reflects relative relationship of total body na and water.