Physiology 6 Flashcards
What is the osmolarity of the rubular fluid entering the DCT compared to plasma?
hypo-osmotic
What is the osmolarity of the interstital fluid of the cortexx?
300mosmol/l
What is the effect of ADH?
increase water reabsorption
What is the effect of aldosterone?
increase Na reabsorption and H/K secretion
Whta is the effect of atrial natriuretic hormone?
decrease Na reabsoprtion
What are the effets of PTH?
increase Ca reabsorption and decrease phosphate reabosrption
What is the basal permeability of the DCT to water and urea?
low
What happens in the early distal tubule?
sodium/potassium/2chloride tranport
What happens in the late distal tubule?
Ca; Na; K reabsorption and H secretion
What influences the late collecting ducts permeability to water and urea?
ADH
How is ADH released from the posterior pituitary?
calcium dependent exocytosis
How does ADH affect the collecting duct?
binds to ADH receptors on the baslateral membrane which increase intracellular levels of cyclic AMP which inserts new aquaporins
What happens in the presence of maximal plasma ADH?
tubular fluid equilibrates via aquaporins- water goes down conc. grad
What are the stimulators for ADH release?
hypothalamix smoreceptors
What receptors in the heart affect ADH receptors?
activationg of left atrial stretch receptors
When is aldosterone secreted?
in response to rising potassium or falling sodium in the blood; activation of the renin-angiotensin system
What happens to K when there is no aldosterone?
all K is reabsorbed and none is excreted
What affect does increased K have on the renin-angiotensin system?
directly stimulate the adrenal cortex
How does a decrease in plasma sodium promote aldosterone release?
by the juxtaglmoerular apparatus secreting renin
What are the 3 controls for renin release?
reduced presure in aferent arteriole; macula densa sense decreased sodium; increased sympathetic activity due to reduced BP
Where does aldosterone have its effects?
distal and collecting tubule
How does aldosterone increased sodium reabsorption?
increases sodium-potassium pump; increases expression of sodium channels on apical membrane
When is ANP released?
when atrial muscle cells are mechanicaly stretch due to an increase in the plasma volume
What does ANP promote?
exrcretion of sodium and diuresis
