68: Loop of Henle Flashcards
Thick & thin ascending limbs are dilute since they are _____ to water so no water leaves. The thick ascending limb reabsorbs sodium. Hence, the TAL _____ the tubular fluid by activly reabsorbing (removing from filtrate) Na+ & Cl- without reabsorbing water. This _____ the osmolarity in the tubular fluid.
Urea recycling occurs when volume ______.
Volume contraction = _____.
Thick & thin ascending limbs are dilute since they are impermeable to water so no water leaves. The thick ascending limb reabsorbs sodium. Hence, the TAL dilutes the tubular fluid by activly reabsorbing Na+ & Cl- without reabsorbing water. This decreases the osmolarity in the tubular fluid.
Urea recycling occurs when volume depleted.
Volume contraction = dehydration.
Reabsorptive solute transport in the TA: is essential for diluting the tubular fluid osmolarity when plastma volume is _____-osmotic & concentrating the tubular fluid osmolarity in the collecting duct by maintaining a gradient of intersitial osmolarity driving the reabsoption of water from the collecting duct back into the _____ & concentrating the urine when plasma colume is contracted or _____.
Reabsorptive solute transport in the TA: is essential for diluting the tubular fluid osmolarity when plastma volume is hypo-osmotic & concentrating the tubular fluid osmolarity in the collecting duct by maintaining a gradient of intersitial osmolarity driving the reabsoption of water from the collecting duct back into the circulation & concentrating the urine when plasma colume is contracted or hyperosmotic.
ADH defends against volume contraction and hyperosmolarity by _____ water by increasing water permeability in the _____ duct. Increased plasma osmolarity ____ ADH secretion & decreased plasma osmolarity _____ ADH secretion. In the absence of ADH the collecting duct is impermeable to water, which prevents water reabsorption.
When you rehydrate ADH goes ____.
Concentrated urine = water reabsorption in excess of solute reabsorption & dilute urine = increased solute reabsorption in excess of water reabsorption. Concentrated urine _____ of solutes.
ADH defends against volume contraction and hyperosmolarity by reabsorbing water by increasing water permeability in the collecting duct. Increased plasma osmolarity increases ADH secretion & decreased plasma osmolarity decreases ADH secretion. In the absence of ADH the collecting duct is impermeable to water, which prevents water reabsorption.
When you rehydrate ADH goes away.
Concentrated urine = water reabsorption in excess of solute reabsorption & dilute urine = increased solute reabsorption in excess of water reabsorption. Concentrated urine stinks of solutes.
The osmolarity of the tubular fluid in the diluting segment of the nephron is always ____ than the osmolarity of the plasma in the presence or absence of ADH since the thin ascending limb, thick ascending limb, and distal convoluted tubule is _____ to ADH.
The controlling variable determining excretion of a dilute or concentrated urine is the level of ____ which modulates water permeability in the collecting duct.
More water is returned to the circulation when ADH is high and when plasma volume is ______ , and less water is returned to the circulation when ADH is low and the plasma volume is _______.
The osmolarity of the tubular fluid in the diluting segment of the nephron is always less than the osmolarity of the plasma in the presence or absence of ADH since the thin ascending limb, thick ascending limb, and distal convoluted tubule is insensitive to ADH.
The controlling variable determining excretion of a dilute or concentrated urine is the level of ADH which modulates water permeability in the collecting duct.
More water is returned to the circulation when ADH is high and when plasma volume is contracted and hyper-osmotic, and less water is returned to the circulation when ADH is low and the plasma volume is expanded and hypoosmotic.
Thin descending limb of the loop of henle has _____ permeability to solutes like salt & urea & _____ permeability to water.
The thin ascending limb of the loop of henle has _____ salt & urea reabsorption, but is water ______.
The thick ascending limb has _____ salt reabsorption via the Na/K/2-Cl transporter, is water _____, and generates and maintains a 200 mOsm gradient between the tubular fluid in the lumen, which is _____ concentration & the interstitium which is _____ concentration.
Thick ascending limb has _____ for active solute reabsorption.
Thin descending limb of the loop of henle has low permeability to solutes like salt & urea & high permeability to water.
The thin ascending limb of the loop of henle has passive salt & urea reabsorption, but is water impermeable.
The thick ascending limb has active salt reabsorption via the Na/K/2-Cl transporter, is water impermeable, and generates and maintains a 200 mOsm gradient between the tubular fluid in the lumen which is low concentration & the interstitium which is high concentration.
Thick ascending limb has mitochondria for active solute reabsorption.
Mnemonic: thick ascending limb is fat due to # of transporters which do ACTIVE reabsorption of salt.
There is a lumen positive voltage difference in the thick ascending limb due to potassium and chloride channels within the cell that keep the inside of the cell ______.
There is a lumen positive voltage difference in the thick ascending limb due to potassium and chloride channels within the cell that keep the inside of the cell negative.
The loop of henle generates and maintains a large cortico-medullary osmotic gradient by a process of ____ multiplication or amplifying 6 fold the capacity of the TAL to ____ solute against a 200 mOsm difference in transtubular osmolarity.
The loop of henle generates and maintains a large cortico-medullary osmotic gradient by a process of countercurrent multiplication or amplifying 6 fold the capacity of the TAL to pump solute against a 200 mOsm difference in transtubular osmolarity.
Antidiuesis = _____ so ADH is released.
Inner medulla has a _____ concentration of solutes (____ than cortex).
Urea keeps being recycled when _____ is present.
Antidiuesis = dehydrated so ADH is released.
Inner medulla has a high concentration of solutes (higher than cortex).
Urea keeps being recycled when ADH is present.
The blood supply of the loop of henle in the medulla is the U shaped vasa recta which is specialized for _____ countercurrent exchange which preserves the corticomedullary gradient of osmolarity. There is a _____ rate of blood flow through the vasa recta which is peritubular & surrounds the loop of henle.
The blood supply of the loop of henle in the medulla is the U shaped vasa recta which is specialized for passive countercurrent exchange which preserves the corticomedullary gradient of osmolarity. There is a slower rate of blood flow through the vasa recta which is peritubular & surrounds the loop of henle.
What is the purpose of urea recycling?
Only a portion of the urea in the filtrate leaves the collecting duct. This additional urea in the interstitial fluid helps “pull out” more water from the filtrate by osmosis. Hence, urea is critical in water reabsorption @ the collecting duct.
Antidiuresis = plasma low & blood osmolarity is _____.
In antidiuresis or dehydration urea recycling occurs due to the presence of _____ which increases the collecting duct’s permeability to urea.
120 mOsm is the same whether you are hypo or hyperosmotic in the ____—the action of ADH is on the _____ duct.
In diuresis or over-hydration, urea recycling does ___ occur.
Antidiuresis = plasma low & blood osmolarity is high.
In antidiuresis or dehydration urea recycling occurs due to the presence of ADH which increases the collecting duct’s permeability to urea.
120 mOsm is the same whether you are hypo or hyperosmotic in the distal tubule—the action of ADH is on the collecting duct.
In diuresis or over-hydration, urea recycling does not occur.
