True/false: excess sodium alone leads to isotonic expansion of the ECF
False; sodium alone would not be isotonic, it would lead to expansion of ECF by drawing water from ICF
True/false: excess sodium and water leads to isotonic expansion of the ECF only
True
What is the body osmolarity normally set at?
290 mOsm/L
What does isosmotic urine mean?
Osmolarity of urine equals to blood osmolarity
What is hyperosmotic urine in relation to blood osmolarity
Higher concentration of solute
What is hypoosmotic urine in relation to blood osmolarity
Lesser concentration of solute
How does the body respond to water deprivation?
Osmoreceptors in the hypothalamus produces ADH for posterior pituitary releases ADH to principal cells in late distal tubule and collecting duct
ADH ______ plasma osmolarity and _____ urine volume and _____ urine osmolarity
Decreases
Decreases
Increases
High osmolarity is ______ in solute and ____ in water
High
Low
Drinking water would ____ urine osmolarity
Decrease
Is the medullary interstitium hyper or hypo osmotic?
Hyperosmotic
True/false: overhydration can lead to washout of the medullary interstitium
True
Water is pulled from the _____ loop of henle to equilibrate with the interstitium, while NaCl is pulled from the _____ loop to add to the interstitium gradient
Descending
Ascending
True/false: NaCl absorption in the ascending limb increases the osmolality in the interstitial fluid
True
Osmolality is higher ________
Deeper into the medulla
Where is urea filtered? Reabsorbed to the outer medulla? Secreted? Reabsorbed to the inner medulla?
Proximal tubule
Proximal tubule
Thin limbs of loop of henle (both thin descending and ascending)
Collecting ducts
True/false: urea is reabsorbed in the proximal tubule
True,
True/false: urea is reabsorbed in the collecting ducts
True, moving to the interstitial fluid to increase the osmotic gradient
True/false: ADH stimulates a specific urea uniporter in the inner medullary collecting ducts to increase urea reabsorption
True, this would draw more water out too
True/false: the efferent arterioles from many of the juxtamedullary glomeruli extend down into the outer medulla
true; forming parts to the vasa recta which helps move fluid in the interstitium back to the capillaries
Vasa recta pulls solutes in as it is _____ and losing that solute as it _______
Descending
ascending
Vasa recta flow is a ____ (high/low) flow
Low
True/false: sodium is reabsorbed from the thick ascending limb into the outer medulla and distributed to the inner medulla via descending vasa recta
How is urine osmolarity regulated?
Using ADH and medullary osmotic gradient
Where is ADH produces and where are the neurons located
Hypothalamic neurons located in the supraoptic and paraventricular nuclei
Where is ADH released?
Posterior pituitary
How does ADH work?
Through G-protein to insert aquaporin channels into the luminal membrane of the principal cells
What happens to plasma osmolarity is ADH and thirst system is blocked?
plasma osmolarity goes way up (aka high salt, low water)
What happens to ADH when there is decreased cardiovascular pressure and less firing by the baroreceptors?
The inhibition on ADH release is no longer there with baroreceptors not firing, so ADH release is increased
ADH is also known as?
Vasopressin
True/false: ADH concentration can get so high that it has a direct effect on arterioles leading to an increased to total peripheral resistance and thus arterial blood pressure goes up
True
True/false: Less ADH would lead to reduced pressure on the baroreceptors
True; since less ADH means that less water getting reabsorbed so blood pressure would lower
Paraventricular nuclei is more important for ______, while supraoptic nuclei are more important for _____.
ADH release
Osmoregulation
True/false: Angiotensin II is also a potent thirst stimulator
True
At which concentration does ADH start to circulate in the blood?
280 mOSm/kg (normal is 290 mOSm/kg)
True/false: body is more sensitive to volume changes than it is to osmotic changes
False; body is more sensitive to osmotic changes, and would affect plasma ADH more
Which is more sensitive osmoreceptors or baroreceptors?
Osmoreceptors
Unless it is a large pressure change, then baroreceptors take precedence
True/false: pregnant women can have vasopressinase in their system produced by the placenta, and thereby breaking down ADH
True
What would be an example nephrogenic deficit that would result in faulty ADH functioning?
Lithium prevents the insertion of aquaporin channels in the collecting duct by limiting cAMP production
What is pressure natriuresis?
Increases in renal artery pressure leading to loss of sodium and water
Na+/K+/2Cl- symporter is found in which segment?
Thick ascending loop of henle
Concentrated urine would have ______ solutes in the interstitial fluid composition.
High; as in more solutes so drawing more water out of the ducts, therefore resulting in concentrated urine
Maximum diuresis is ___ (maximum/no) ADH.
No
Maximum antidiuresis is ____ (maximum/no) ADH.
Maximum
What is the most effective player in long-term control of sodium balance?
Aldosterone
True/false: aldosterone affects sodium transport in sweat and salivary ducts and the intestine
True
Where is aldosterone produced?
Adrenal glands (zona glomerulosa)
True/false: aldosterone is produced in the hypothalamus
False; aldosterone is produced in the adrenal gland, ADH is produced in the hypothalamus
What stimulates the release of aldosterone?
Angiotensin II and plasma potassium levels
True/false: ADH stimulates the release of aldosterone
False; angiotensin II does, it is part of the RAAS system
Aldosterone has to do with ____ plasma level, and ADH has to do with _____ plasma level
Na+
Water
True/false: decrease in NaCl at the macula densa leads to increase renin release from the granular cells
True
Which type of nerve stimulates renin secretion from granular cells?
Renal sympathetic nerve
True/false: renal sympathetic nerve activity constrict the afferent arteriole to increase GFR and renal blood flow
False; it decreases GFR and RBF
Angiotensin II leads to _________
Vasoconstriction
How does angiotensin II affect renal sodium reabsorption?
Increases renal sodium reabsorption to expand ECF volume
Where in the tubule does angiotensin II act on?
Proximal tubule to affect Na-H exchange
Where in the tubule does aldosterone act on?
Collecting tubule
Angiotensin II mostly constrict ____ arteriole, but also to a lesser degree ___ arteriole as well.
Efferent
Afferent
True/false: aldosterone is a steroid hormone
true
What inhibits aldosterone secretion?
Atrial natriuretic peptide inhibits aldosterone secretion by inhibiting renin release
True/false: ANP inhibits renin and angiotensin II release thereby inhibiting aldosterone secretion
True
True/false: ADH is involved in the RAAS
False; it is Renin-> angiotensin II -> aldosterone
Angiotensinogen is from the ______ , and converted to angiotensin II in _______.
Liver
Lungs
True/false: atrial natriuretic peptide is made in the kidneys
False; it is made in the heart by distension of the atria
Atrial natriuretic peptide has what effect on afferent arteriole? Efferent arteriole?
Relaxes afferent arteriole and increases filtration
Constricts efferent arterioles
ANP has what effect on GFR?
Increases
ANP is secreted in response to what?
increased sodium intake
What is ANP’s effect on sodium reabsorption in the collecting duct?
Inhibits it
True/false: ANP is more effective at plasma volume control than ADH
False; ANP is less effective than ADH for plasma volume control
Which hormones indirectly increase sodium reabsorption?
