renal part 6 Flashcards
How is water reabsorption regulated in the human body?
A) ADH increases water permeability in the collecting ducts by inserting AQP2 into the luminal membrane.
B) Aldosterone increases water reabsorption by stimulating Na+ excretion.
C) ANP stimulates aquaporin expression to increase water reabsorption.
D) Water reabsorption is independent of hormone regulation.
hormone ADH (anti-diuretic hormone) or vasopressin alters water permeability
how is ADH secreted and when does it get released? where does it do its action
ADH is a peptide hormone that is secreted when osmoreceptors in the hypothalamus sense an increase in plasma osmolarity
they are made by SON cells of the hypothalamus and secretetd from the posterior pituirary
ADH acts on the luminal membrane of collecting ducts and regulates water channels by maintaining aquaporins
What are the sources of ADH? How does it work in maintaining water balance?
A) ADH is produced by the posterior pituitary and increases Na+ excretion to retain water.
B) ADH is secreted by the hypothalamus and regulates aquaporins in the collecting duct to promote water reabsorption.
C) ADH is secreted by the juxtaglomerular apparatus and increases aldosterone secretion.
D) ADH is released from the adrenal cortex and enhances renin production.
ADH is secreted by the hypothalamus and regulates aquaporins in the collecting duct to promote water reabsorption.
how does ADH/vasopressin act when there is not a lot of urine voided? how about when there is a high volume of urine?
low volume voided:
means there is high ADH being active (water retention). osmolarity increases in the collecting duct
high volume voided:
urine is diluted, ADH is not active, osmolarity gradient in the collecting duct decreases
What is diabetes insipidus? What are the two types?
A) A condition where the body retains too much water, leading to low urine output; central and nephrogenic types.
B) A disorder characterized by excessive urine production due to ADH deficiency or resistance; central and nephrogenic types.
C) A condition caused by increased aldosterone secretion, leading to excessive Na+ loss.
D) A disorder where glucose in the urine causes excessive water loss; osmotic and water diuresis.
A disorder characterized by excessive urine production due to ADH deficiency or resistance; central and nephrogenic types.
a disease where there is a failure of releasing ADH from posterior pituitary
central diabetes insipidus
what are the two condtitions of diabetes insipidus?
central diabetes inspidus and nephrogenic diabetes insipidus
how does ADH increase with tempurature?
ADH increases by shock, pain, warm and hot weather, and water deprivation
ADH decreases in colder, humid environemtns, and when alcohol is being consumes (more pee, dilute urine)
What are aquaporins? What are the different types found in the renal system?
A) Na+ transporters found in the kidney tubules that regulate urine concentration.
B) Protein channels that facilitate water transport across cell membranes; AQP1 in proximal tubules, AQP2, 3 and 4 in collecting ducts.
C) Hormones that increase water reabsorption in the nephron; AQP2 is stimulated by ANP.
D) Enzymes that regulate sodium balance; found in the distal tubule and collecting duct.
Protein channels that facilitate water transport across cell membranes; AQP1 in proximal tubules, AQP2, 3 and 4 in collecting ducts.
Which type of aquaporin is involved in water volume regulation?
A) AQP1
B) AQP2
C) AQP3
D) AQP4
AQP2
how does water diuresis and osmotic diuresis different
water diuresis: condition where only excess water is excreted without excess solute in urine (when your pee is very dilute and your urine volume is large)
osmotic diuresis: when you have excess solute in urine , causing extra water to be pulled out (recall: water always follows solutes)
eg. diabetes mellitus
what does measuring plasma sodium concentration determine
determines plasma osmolarity
A change in sodium concentration in the blood affects blood volume and blood pressure because:
A) Sodium determines plasma osmolarity, which influences water movement between compartments, affecting extracellular fluid volume and blood pressure.
B) Increased sodium retention leads to water retention, increasing extracellular fluid volume, blood volume, and blood pressure.
C) Decreased sodium levels reduce plasma osmolarity, leading to water loss, decreased blood volume, and lower blood pressure.
D) All of the above.
d
This question directly uses information from the notes:
Sodium concentration is closely linked to extracellular fluid volume.
Plasma osmolarity is largely determined by sodium levels.
Changes in sodium levels alter water balance, which affects blood volume and blood pressure.
. What is the intracellular mechanism involved in regulating aquaporins?
A) ADH binds to receptors, activating cAMP, which promotes AQP2 insertion into the luminal membrane.
B) Aldosterone directly inserts aquaporins into the luminal membrane of the proximal tubule.
C) ANP inhibits aquaporin expression by stimulating renin release.
D) Water channels are constitutively expressed and do not require hormonal regulation.
ADH binds to receptors, activating cAMP, which promotes AQP2 insertion into the luminal membrane.
how does a low sodium concentration in the plasma affect the short term and long term of handling low levelsÉ
short term low sodium conditions: baroreceptors regulate GFR
long term: aldosterone regulates low levels and promotes Na+ reabsorption
renin, aniotensin 2 are needed for aldosterone secretion
how is high sodium concentration in plasma regulated?
regulated by ANP (atrial natriuretic peptide)
- this hotmone regulates GFR and inhibits sodium reabsorption (too much sodium has to go)
- ANP inhibits the actions of aldosterone
What are the mechanisms involved in Na+ regulation?
A) Aldosterone increases Na+ reabsorption, ANP increases Na+ excretion.
B) Renin-angiotensin system increases Na+ excretion, ANP inhibits Na+ transporters.
C) ADH increases Na+ reabsorption, aldosterone increases Na+ filtration.
D) Na+ regulation is independent of hormone signaling.
Aldosterone increases Na+ reabsorption, ANP increases Na+ excretion.
Where is aldosterone synthesized? How is it involved in regulating Na+ levels?
A) Secreted by the posterior pituitary; stimulates Na+ excretion in the nephron.
B) Produced by the adrenal cortex; increases Na+ reabsorption in the distal tubule and collecting duct.
C) Synthesized in the liver; inhibits Na+ transporters in the kidney.
D) Released from the hypothalamus; stimulates renin production.
Produced by the adrenal cortex; increases Na+ reabsorption in the distal tubule and collecting duct.
What are baroreceptors and how are they involved in Na+ regulation?
Baroreceptors detect stretch in blood vessels and regulate Na+ balance through sympathetic activation.
what is the sequence of baroreceptors working
- detection of low plasma volume and low arterial blood pressure activate baroreceptors
- less stretch
- increased activity of renal sympathetic nerves
- increased afferent arteriolar constriction
- decreased GFR
- less sodium filtered and excreted
- increased sodium in plasma
a steroid hormone with ling term effects secreted from the adrenal cortex, low sodium concentrations trigger its secretion and synthesis
aldosterone
what are the actions of aldosterone?
- stimulates sodium reabsorption
- reduces sodium excretion
- induces synthesis of Na+ transport protein (increases reabsorption)
*acts in the distal tubule and collecting duct
what is the mechanism of aldosterone?
dosium absorption is linked to potassium secretion
-nosium potassium atpase generates a gradient, as a result sodium comes into the cell from the tubular lumen
Aldosterone increases sodium reabsorption, but at the same time, it also stimulates potassium secretion. This occurs because:
A) Sodium reabsorption through ENaC channels creates a negative charge in the lumen, which pulls K+ out of the cell.
B) The Na+/K+ ATPase pump moves Na+ into the blood and K+ into the tubular cell, increasing K+ secretion into the urine.
C) Increased sodium reabsorption causes water retention, which passively increases potassium excretion.
D) Both A and B are correct.
NOTE SODIUM REABSORPTION IS LINKED TO POTASSIUM SECRETION INTO THE TUBULAR LUMEN
Both A and B are correct.
