ECF Volume Regulation Flashcards
What are the two major ECF osmoles?
Na+ and Cl-
What is the major ICF osmole?
K+
What is the result of ECF volume regulation?
Regulation of body Na+
What occurs if there is a change in Na+ concentration in ECF?
ECF volume changes, the volume of blood perfusing tissues changes and thus,circulating volume and BP are affected
What is the renal response to a decrease in ECF volume?
Hypovolaemia
When is there an increase in salt and a loss of water?
Vomiting, diarrhoea or excess sweating
What is the effect of an increased salt concentration and a net loss of water?
Decrease in Plasma Volume, decrease in venous pressure, decrease in Venous Return, a decrease in atrial pressure, a decrease in End Diastolic Volume and stroke volume= Decreased Cardiac output and stroke volume which DECREASES CAROTID SINUS BARORECEPTOR INHIBITION OF SYMPATHETIC DISCHARGE
What affects do decreased atrial pressure and decreased carotid sinus discharge have on ADH?
Increases ADH concentration
What affect does an increase in sympathetic discharge have on renin concentration?
There is an increase in renal VC nerve activity which increases renal arteriolar constriction and thus there is an increased in renin
What affect does an increase in renin concentration have on peritubular capillary hydrostatic pressure?
Inc. Renin, inc. angiotensin II which decreases PC hydrostatic P = increase in Na reabsorption and a decrease in Na excretion
What affect does an increase in renin concentration have on aldosterone?
Increased renin, increased Angiotensin II = increased aldosterone = increase in Na reabsorption and decrease in Na excretion
What is Na+ reabsorbtion controlled by?
Aldosterone
What do Juxtoglomerular Cells produce?
Renin
What does renin act on?
The alpha 2 globulin fraction of angiotensinogen
What controls renin release ?
- Afferent arteriole pressure at level of JG cells decreases
2 Increases sympathetic nerve activity
- Decreased NaCl delivery at macula densa
- Angiotensin II feeds back to inhibit renin
- ADH inhibits renin release