Physiology Renal Exam 4 (IP2): Renal Processes for Na+, Cl-, and H2O II Lecture

water reabsorption occurs at several points throughout the tubule, the amount is dependent on differences in water ______

permeability

there is (high/low/regulated) permeability to water in the proximal tubule

high

there is (high/low/regulated) permeability to water in the descending loop of henle

high

there is (high/low/regulated) permeability to water in the ascending loop of henle

low

there is (high/low/regulated) permeability to water in the late distal and collecting ducts

regulated

water reabsorption occurs via what two pathways/transport

1. Osmosis

2. Passively - Paracellular (simple) and transcellular (facilitated)

When water movement is paracellular, this is (active/passive) (primary/secondary/simple/facilitated)

passive, simple

When water movement is transcellular, this is (active/passive) (primary/secondary/simple/facilitated)

passive, facilitated

transcellular transport of water is through channels called what?

aquaporins

T/F: aquaporins are found on both the basolateral and apical membranes

true

are aquaporins water selective channels?

yes

aquaporins allow the rapid movement of water from the (interstitial space/tubule lumen) into the (interstitial space/tubule lumen)

tubule lumen, interstitial space

where in the nephron are aquaporins expressed?

proximal tubule and descending loop of henle (regulate expression in late distal/collecting tubules as well)

there is normally low expression of aquaporins on the apical side of which two parts of the nephron? Their expression can be increased by antidiuretic hormone

late distal, collecting tubules/duct

What hormone has the ability to increase the expression of aquaporins in the late distal tubule and collecting tubules/duct

antidiuretic hormone

water reabsorption is tightly coupled to _________ reabsorption

sodium

sodium reabsorption (increases/decreases) the osmolarity of the interstitial fluid in relation to the tubule lumen which drives osmosis of water from the (ISF/tubule) to the (ISF/tubule)

increases, tubule, ISF

T/F: the same forces that drove fluid from the glomerular capillaries into the tubule apply to the absorption of water from the ISF into the peritubular capillaries

true

Out of these forces listed, which forces are responsible for driving fluid from the ISF into the capillaries?

- ISF osmotic pressure

- Capillary osmotic pressure

- Capillary hydrostatic pressure

- ISF hydrostatic pressure

capillary osmotic pressure, ISF hydrostatic pressure

Out of these forces listed, which forces are responsible for driving fluid from the capillaries into the ISF?

- ISF osmotic pressure

- Capillary osmotic pressure

- Capillary hydrostatic pressure

- ISF hydrostatic pressure

capillary hydrostatic pressure, ISF osmotic pressure

hydrostatic pressure is very (high/low) in the peritubular capillaries

low

because peritubular hydrostatic pressure is very low, water reabsorption is primarily driven by what kind of pressure?

capillary osmotic pressure

the (smaller/larger) the difference is between forces, the stronger the drive is for reabsorption

larger

the kidneys dilute urine when water is in (deficit/excess)

excess

the kidneys concentrate urine when water is in (deficit/excess)

deficit

how many mLs of urine MUST a mammal produce a day in order to excrete waste

200

the ability of the nephron to concentrate or dilute urine is dependent on what two factors

1. characteristics of the loop of henle

2. regulated water permeability of the late distal/collecting tubules and duct

what characteristics of the loop of henle make the nephron dependent on it for urine concentration and dilution

solute and water permeability in the descending vs ascending limbs

what characteristic of the late distal/collecting tubules and duct make the nephron dependent on it for urine concentration and dilution

regulated water permeability via antidiuretic hormone

The proximal tubule has (high/regulated/low) permeability to water

high

The proximal tubule has (high/regulated/low) permeability to solutes

high

The descending limb of the loop of henle has (high/regulated/low) permeability to water

high

The descending limb of the loop of henle has (high/regulated/low) permeability to solutes

low

The ascending limb of the loop of henle has (high/regulated/low) permeability to water

low

The ascending limb of the loop of henle has (high/regulated/low) permeability to solutes

high

The late distal/collecting tubules and duct have (high/regulated/low) permeability to water

regulated

The late distal/collecting tubules and duct have (high/regulated/low) permeability to solutes

regulated

which best describes the proximal tubule?

- Concentration/dilution of urine

- Fine tuning

- Is osmotic to plamsa

is osmotic to plasma

which best describes the descending limb of the loop of henle?

- Concentration/dilution of urine

- Fine tuning

- Is osmotic to plamsa

concentration/dilution of urine

which best describes the ascending limb of the loop of henle?

- Concentration/dilution of urine

- Fine tuning

- Is osmotic to plamsa

concentration/dilution of urine

which best describes the late distal/collecting tubules and duct?

- Concentration/dilution of urine

- Fine tuning

- Is osmotic to plamsa

fine tuning

the loop of henle extends into the (cortex/medulla) and consists of how many parts?

medulla, 3

what are the three parts of the medulla?

thin descending, , thin ascending, thick ascending

the thin descending limb has:

- (high/low) permeability to water

- (has/doesn't have) aquaporins

- has (high/low) permeability to solute

- (has/doesn't have) solute transporters

- high

- has

- low

- doesn't have

the thick ascending limb has:

- (high/low) permeability to water

- (has/doesn't have) aquaporins

- has (high/low) permeability to solute

- (has/doesn't have) solute transporters

- low

- doesn't have

- high

- has

what is the name of the transporter that is present on the apical membranes of the cells in the thick ascending limb of the loop of henle?

sodium potassium chloride co transporter (NKCC)

In the loop of henle the filtrate is:

- At the beginning (hyposmotic/isosmotic/hyperosmotic)

- At the bottom (hyposmotic/isosmotic/hyperosmotic)

- At the end (hyposmotic/isosmotic/hyperosmotic)

- isosmotic

- hyperosmotic

- hyposmotic

the medulla becomes very (hyposmotic/isosmotic/hyperosmotic) which allows for the rapid reabsorption of water and concentration of urine

hyperosmotic

even though the filtrate is dilute at the end of the loop of henle, the volume is greatly (increased/decreased)

decreased

the (shorter/longer) the loop of henle, the more concentrated an animal can make its urine

longer

the longer the loop of henle, the (less/more) concentrated an animal can make its urine

more

The permeability of the distal and collecting tubule to water is increased by what hormone

anti diuretic hormone

do the distal and collecting tubules usually have a high or low permeability to water

low

aquaporins are present on the basolateral or apical membrane in the late distal/collecting tubules

apical

which kinase is a huge driver of surface expression of aquaporins?

protein kinase A

Low ADH levels

- (less/more) dilute urine

- (lower/higher) urine volume

- (water/anti) diuresis

- more

- higher

- water

high ADH levels

- (less/more) dilute urine

- (lower/higher) urine volume

- (water/anti) diuresis

- less

- lower

- anti

the counter multiplier mechanism occurs in which part of the nephron

loop of henle