ECF Volume Regulation Flashcards
What are the two major osmoles in the ECF?
Na⁺ and Cl⁻
What is the major osmole in the ICF?
K⁺
What does an increase in sympathetic discharge do in the kidneys?
Increases renal vasoconstriction nerve activity
Increased renal arteriolar constriction
Increase in renin
An increase in renin causes?
Increased angiotensin II
Decreased peritubular capillary hydrostatic pressure
Increased sodium reabsorption from the proximal tubule
Decreased sodium excretion
Increased [angiotensin II] also causes?
Increased aldosterone
Increased distal tubule sodium reabsorption and decreased sodium excretion
The afferent arteriole
Enters the glomerulus (A - beginning)
The efferent arteriole
Exits the glomerulus (E - End)
In the Renin Angiotensin Aldosterone System, what is the rate limiting step?
Renin, converts angiotensinogen to angiotensin I
Angiotensinogen is always being produced by the liver. Angiotensin I converted by ACE into Angiotensin II
Angiotensin II stimulates aldosterone secreting cells in the zona glomerulosa of the adrenal gland (Salt)
What effect does aldosterone have on distal tubules?
Sodium reabsorption and potassium excretion
What feeds back to inhibit renin release?
Angiotensin II and ADH
Decreased delivery of NaCl to the macula densa cells causes
Increased renin release
What opposes the action of angiotensin II?
Atrial natriuretic peptide (ANP) causes sodium excretion
What is Conn’s syndrome
Hyperaldosteronism
Why is a patient with Conn’s hypokalaemic but not hypernatremic?
The high levels of ALDR cause Na⁺ reabsorption and K⁺ excretion, but as the ECF expands atrial cells release ANP to excrete sodium and water. Hypokalaemia remains
What causes osmotic diuresis?
Uncontrolled diabetes mellitus
