Physiology - Endocrine Control Flashcards
what does the distal tubule empty into?
the collecting duct
what are the major sites in the kidney for regulation of ion and water balance?
distal tubule
collecting duct
what is another name for ADH?
vasopressin
what effect does ADH have on water?
increases water reabsorption
what effect does aldosterone have on ions?
increases sodium reabsorption
increases H+ and K+ secretion
what effect does ANH have on ions?
reduces sodium reabsorption
what is ANH?
anti natriuretic hormone
what effect does PTH have on ions?
increased calcium reabsorption
decreases phosphorus reabsorption
what is the permeability like to water and urea in the distal tubule?
low
can be increased by ADH
what are the two segments of the distal tubule?
early
late
what happens in the early distal tubule?
NaCl reabsorption
what happens in the late distal tubule?
calcium reabsorption
H secretion
sodium reabsorption
potassium reabsorption
what do levels of sodium and potassium reabsorption in the distal tubule depend on?
aldosterone levels
what does aldosterone promote in the late distal tubule?
potassium secretion
where is ADH released from?
posterior pituitary
when is ADH released from the posterior pituitary?
when AP’s down the nerves lead to calcium ion dependent exocytosis
what is the primary stimulus for ADH release?
dehydration
how does dehydration lead to ADH release?
dehydration = increased plasma osmolarity
detected by osmoreceptors in the hypothalamus
stimulates nerves = secretion of ADH
what is the plasma half life of ADH?
10-15 minutes
what is the effect of high ADH?
increases water permeability hypertonic urine (very concentrated)
what is the effect of low ADH?
low water permeability hypotonic urine (very dilute)
what is aldosterone?
a steroid hormone secreted by the adrenal cortex
when is aldosterone secreted?
response to rising K+ or falling Na+
after activation of the RAAS
what does aldosterone stimulate?
sodium reabsorption
potassium secretion
what does sodium retention due to aldosterone contribute to?
increased blood pressure
what is another name for ANH?
atrial natriuretic peptide
what produces ANP?
the heart
stored in atrial muscle cells
when is ANP released?
when the heart cells are stretched due to increased plasma volume
what does ANP promote?
excretion of Na+ and diuresis
= decreased plasma volume
what is the process by which urine is emptied from the bladder?
micturition
what are the two mechanisms that control micturition?
the micturition reflex
voluntary control
what is the micturition reflex?
involuntary emptying of the bladder triggered by stretching of the bladder wall, picked up by stretch receptors
