Regulation of Extracellular Sodium and Water Flashcards
What is the normal concentration of Na+ in the ECF?
140mM
T/F: Increases in ECF sodium amount cause a corresponding increase in ECF volume.
F. Since sodium is the major osmotic determinant, ECF sodium changes result in a volume change, rather than a [NA] change
How is sodium concentration monitored in the body?
Through blood pressure, since sodium concentration drives the equilibrium of water between ICF and ECF.
An increase in aldosterone leads to what?
An increase in sodium reabsorption in the distal convoluted tubule and collecting duct
In addition to its vasoconstrictive role, AgII functions to increase synthesis of ______
Aldosterone
Where is ADH synthesized?
Hypothalamus
Where is ADH released from?
Posterior pituitary
For regulation of ECF water, is volume or osmolarity measured?
BOTH!!
Which baroreceptors are most important in monitoring ECF volume?
The ones in the left atrium.
Describe the tonicity of sweat.
Hypotonic
Describe the tonicity of diarrhea.
Isotonic
ECF water regulation is primarily a ______ system with an emergency _____ override.
Osmoregularity; low-volume
What hormone is responsible for diuresis in the case of volume overload?
ANP (Atrial natriuretic peptide)
Where does ANP come from?
Atrial cardiocytes
How does ANP act on the afferent and efferent arterioles?
It causes vasodilation in both. Increases GFR.
How does ANP act on the brain?
It decreases the synthesis and release of ADH
How does ANP effect renin secretion?
ANP decreases renin secretion.
What is the ultimate effect of ANP?
Massive diuresis with accompanied natriuresis.
