3&4 Flashcards
The kidneys maintain the osmolality and volume of body fluids within a narrow range by regulating the __________________.
Excretion of water and NaCl, respectively.
Disorders in water balance are manifested by alterations in body fluid osmolality, whc are usually measured by changes in _______________.
plasma osmolality Posm
The major determinant of Posm
Na+ (wt its anions Cl- and HCO3-)
Acts on the kidneys to regulate the volume and osmolality of the urine.
AntiDiuretic Hormone/ Vasopressin
Low plasma ADH levels = large vol of urine excreted; dilute urine
Diuresis
High plasma ADH levels = small vol urine excreted; conc urine
Antidiuresis
Hypoosmolality, shifts water _____________, and this results in cell _____________.
Water into the cells,
Swelling
Symptoms of a rapid fall in Posm
Can alter neurological function = nausea, malaise, headache, confusion, lethargy, seizures, and coma
Symptoms of an increase in Posm
Primarily neurological
- lethargy
- weakness
- seizures
- coma
- death
Where is ADH synthesized?
In the neuroendocrine cells located wthn the supraoptic* and paraventricular nuclei of the hypothalamus
Where is ADH stored?
Nerve terminals located in the hypophysis (post pit)
Factors that influence secretion of ADH
Osmotic ctrl
Hemodynamic ctrl
Others
Stimulates secretion of ADH
Nausea
Ang II
Nicotine
Inhibits secretion of ADH
Atrial natriuretic peptide
Ethanol
These cells termed ______________, appear to behave s osmometers and sense changes in body fluid osmolality by either shrinking or swelling.
Osmoreceptors
When the effective osmolality of plasma increases, synth and secretion of ADH are ____________.
When the effective osmolality of plasma is reduced, secretion is ____________.
Stimulated,
Inhibited
Because ADH is repidly degraded in plasma, circulating levels can be reduced to 0 in minutes aft secretion is inhibited.
As a result, the ADH system can respond rapidly to fluctuations in body fluid osmolality.
A decrease in blood volume or pressure ____________ secretion of ADH.
Stimulates
Location of receptors responsible for hemodynamic control
Low pressure (left atrium & large pulm vessels) & the high pressure (aortic arch & carotid sinus) sides of the circulatory system
Bradykinin and histamine which _________ pressure thus ___________ ADH secretion.
NE, which __________ blood pressure, ____________ ADH secretion.
Lower, stimulate
Increases, inhibits
The primary action of ADH on the kidneys
To increase the permeabiliy of the collecting duct to water.
In addtn, ADH increases the prmeability of themedullary portion of the collecting duct to urea.
ADH stimulates reabsorption of NaCl where?
By the thick ascending loop of henle, distal tubule, and the collecting duct
Actions of ADH on the kidneys
- (1*) increase permeability of the collecting duct to water
- increase permeability of the medullary portion of the collecting duct to urea
- stimulates reabsorption of NaCl in the TALH, distal tubule, and collecting duct
ADH also ________ th permeability of the terminal portion of the inner medullary collecting duct to urea. This results in an __________ in reabsorption of urea and an ___________ in the osmolality of the medullary interstitial fluid.
Increase, increase, increase
