6 Volume Homeostasis Flashcards
What is the main cation in ECF?
Na+
T/F: Changes in K+ content of ECF result in changes in ECF volume.
F: Changes in Na+, not K+, results in corresponding changes in ECF volume
What is the main cation in ICF?
K+
What are the main anions in ICF?
PO4-2, organic ions, negatively charged proteins (not albumin)
What is the main anion in ECF?
Cl-
What does positive Na+ balance mean?
Retention of Na+ and expansion of ECF
What does negative Na+ balance mean?
Loss of Na+ and contraction of ECF
What is effective circulating volume (ECV)?
It is a sense of fullness of the circulating volume; it is conceptual and cannot be measured
Where are the baroreceptors of the juxtaglomerular apparatus located and to what stimulus do they respond?
It is located in the afferent arterial and responds to high pressure.
What are the three cellular components of the juxtaglomerular apparatus?
Juxta glomerular cells that secrete renin.
Macula densa cells in the distal tubule for Na+ sensor
Mesangial cells for contraction and phagocytosis
What is tubuloglomerular feedback?
The process whereby cells of the macula densa sense NaCl concentrations and alter afferent arteriolar resistance and GFR accordingly
Where is Renin synthesized?
Afferent arteriole
What conditions lead to the secretion of Renin?
Decreased perfusion pressure/wall tension, decreased NaCl concentrations sensed by macula densa, increased sympathetic nerve activity
What are the effects of angiotensin II?
Increased Na+ and water reabsorption in kidney, vasoconstriction, stimulation of thirst and ADH release
What structures are innervated by renal sympathetic nerves?
afferent and efferent arterioles, tubular epithelia, macula densa
