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356 Cards in this Set

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10. The vasa recta

A. is located entirely within the medulla
B. flows immediately and next into the efferent arterioles
C. exits the medulla at the papilla
D. is located within the cortex and the medulla
E. has a plasma that is hypoosmotic throughout its course
A. is located entirely within the medulla

The plasma in the vasa recta will be hyperosmotic, similar to the interstitial fluid through which it passes in the medulla. When the blood exits the vasa recta, and enters the arcuate veins, it is still slightly hyperosmotic.
11. The tubular reabsorption of water is

A. passive
B. always high in the proximal tubule
C. high or low in the collecting duct depending on the level of vasopressin
D. inhibited by the presence of a non-reabsorbable solute in the lumen of the tubule
E. all of the above
11.E. all of the above
12. The secretion of renin is increased by

A. stretch of JG cells
B. increases in mean arterial blood pressure
C. increases in osmolality, regardless of changes in extra cellular volume
D. decreased ANP (atrial naturetic factor)
E. all of the above
D. decreased ANP (atrial naturetic factor)

Remember , that renin secretion will increase in conditions that require an increase in vasoconstriction and an increase in blood pressure. ANP inhibits renin secretion, so a decreased level of ANP would be the same as a decreased level of inhibition, and the renin secretion would increase. Recall that renin is secreted by the juxtaglomerular cells.Renin is the enzyme that is part of the cascade of events leading to angiotensin II, and will increase under conditions in which blood pressure, or extracellular volume, have decreased. Direct stretch of the JG cells will decrease renin (direct stretch is another result of high pressure) An increase in mean arterial blood pressure would decrease renin secretion, not increase it. Osmolality per se has no direct effect on renin.
13. Regarding aldosterone, which of the following is correct?

A. Aldosterone is secreted by the adrenal gland in response to angiotensin II
B. Both the proximal tubule and the collecting tubule are the primary sites of action of aldosterone.
C. Aldosterone directly stimulates the insertion of water channels into the apical membrane
D. Aldosterone levels decrease when renin levels increase
E. the primary effect of aldosterone is to increase Na+ reabsorption in the descending loop of Henle
A. Aldosterone is secreted by the adrenal gland in response to angiotensin II

Aldosterone enhances sodium reabsorption, particularly in the distal tubule and collecting duct. Note that normally, renin and aldosterone levels should either both increase, or both decrease, since renin catalyzes the formation of angiotensin II, and angiotenin II stimulates the secretion of aldosterone. The descending loop of Henle is water permeable, but not salt permeable.
14. Fluid in the distal convoluted tubule is hyposmotic to systemic plasma because

A. water is reabsorbed to a greater degree than salt within the proximal tubule
B. water is secreted into the tubule lumen by the descending loop of Henle
D. sodium reabsorption in the TALH is greater than water reabsorption in the descending loop of Henle
E. cells of the distal convoluted tubule always have a high permeability to water
D. sodium reabsorption in the TALH is greater than water reabsorption in the descending loop of Henle

The tubular fluid first becomes concentrated as it passes through the descending loop, but in the ascending loop sodium is actively transported to an even greater degree, and the fluid becomes hypoosmotic. Water and salt are both reabsorbed to the same degree by the proximal tubule, so this fluid is isosmotic compared to plasma.

Water is never secreted in the descending loop (B). ADH increases water permeability in the late distal tubule
The plasma in the vasa recta will be _______ similar to the interstitial fluid through which it passes in the medulla.
hyperosmotic,
When the blood exits the vasa recta, and enters the arcuate veins, it is still slightly _________.
hyperosmotic.
15. A feature common to cells of the proximal tubules and TALH is

A. prominent apical microvilli
B. basolateral Na+/K+ ATPase
C. Na+/glucose apical symport
D. apical Na+ channel
E. apical vasopressin-regulated aquaporins
B. basolateral Na+/K+ ATPase

This ATPase sets up the electrochemical gradient used by most of the transport systems in the tubules.
Microvilli are prominent only in the proximal tubules (review the functional anatomy). Glucose and other
nutrients are transported only in the proximal tubules.
16. Approximately 20% of the filtered sodium is reabsorbed in the

A. proximal tubule
B. thin descending loop of Henle
C. thick ascending loop of Henle
D. distal convoluted tubule
E. collecting duct
C. thick ascending loop of Henle
17. Diuretics that act on cells of the collecting tubule would

A. decrease the rate of glucose reabsorption in the collecting tubule
B. increase the rate of Na+ reabsorption in the collecting tubule
C. increase the rate of water reabsorption in the proximal tubule
D. have an insignificant effect on daily Na+ excretion
E. have no effect on Na+ reabsorption in the TALH
E. have no effect on Na+ reabsorption in the TALH


there should be no glucose in the tubular fluid once it leaves the proximal tubule, so glucose reabsorption
is unaffected by anything happening in the more distal segments (A). Diuretics act by blocking Na+ reabsorption, not increasing it (B). The transporter in the TALH is different from that in the collecting tubule, so the diuretic would not affect Na+ transport in the TALH, or water reabsorption in the proximal tubule. Although the percentage of filtered Na+ reabsorbed in the collecting duct may be small, the overall effect on Na+ excretion, and therefore ECF volume, is significant(D)

Diuresis and antidiuresis
18. Normally, the tonicity of the tubular fluid as it just enters the collecting tubule is

A. always hypotonic
B. either hypotonic or isotonic, but never hypertonic
C. always hypertonic
D. always isotonic
E. either hypertonic or hypotonic, but never isotonic
A. always hypotonic

The filtrate becomes diluted in the ascending loop of Henle, and by the time it reaches the late distal tubule, it has an osmolality less than that of plasma. From there, the filtrate can increase in osmolality, but only if Vasopressin/ ADH is present, and water is reabsorbed.
19. The cortical nephrons

A. do not have a thin loop of Henle
B. do not contribute to the formation of concentrated urine
C. do not contribute to filtration of the plasma
D. do not contribute solutes to the peritubular capillaries
E. do not have any Na+ transport in the TALH
B. do not contribute to the formation of concentrated urine

They have all of the segments of the nephron, they filter plasma in the glomerular capillaries, and retrun solutes to peritubular capillaries. The real difference is that they do not contribute to the formation of concentrated urine because the concentrating mechanism requires a hyperosmotic interstitium, created by solute transport in the
loops of Henle of the juxtamedullary nephrons.
20. All of the following contribute to the formation of a maximally concentrated urine except:

A. an increased rate of Na+ reabsorption in the proximal tubules
B. impermeability of the TALH to water
C. active transport of Na+ of the TALH
D. passive transport of Na+ across the thin ascending limb
E. apical aquaporins in the collecting duct in the presence of vasopressin
A. an increased rate of Na+ reabsorption in the proximal tubules

Reabsorption of Na+ in the proximal tubules is isoosmotic, so increases in this (as with angiotensin II) do not change the osmolarity of the tubular fluid.
21. If the thick ascending limb of the loop of Henle were somehow made permeable to water:

A. medullary interstitial fluid osmolarity would increase
B. tubular fluid sodium concentration entering the distal tubule would decrease
C. the kidney could no longer produce urine with osmolarity substantially less than plasma osmolarity
D. all of the above
E. none of the above.
C. the kidney could no longer produce urine with osmolarity substantially less than plasma osmolarity

The filtrate becomes diluted in the ascending loop of Henle, and by the time it reaches the late distal tubule, it has an osmolality less than that of plasma. From there, the filtrate can increase in osmolality, but only if ADH is present, and water is reabsorbed. In the absence of ADH, and with no defect in sodium transport (normal aldosterone, etc.), the urine will be hyposomotic.
22. The fraction of filtered water that is reabsorbed in the proximal tubule

A. increases with ADH
B. decreases with ADH
C. is less than the fraction reabsorbed in the loop of Henle
D. is less than the fraction reabsorbed in the collecting ducts in the presence of ADH
E. is unchanged by ADH
E. is unchanged by ADH

ADH stimulates the synthesis of water channels in the late distal tubule and collecting ducts. The water
channels in the proximal tubules are always present (constitutive), and do not depend in any way on the level of ADH. Therefore, ADH will have no effect on the reabsorption of water in the proximal tubules, which is normally about 65-70%.
23. The condition of diuresis differs from that of diuresis in the osmolarity of

A. proximal tubules
B. distal convoluted tubules
C. collecting ducts
D. thin descending loop of Henle
E. all of the above
C. collecting ducts

The primary difference between diuresis and antidiuresis is in the osmolarity of the fluid in the collecting tubules.

Regulation of ECF volume and osmolarity
24, An increase in the osmolality of the extracellular fluid will:

A. stimulate the osmoreceptors and increase vasopressin secretion
B. stimulate the osmoreceptors and decrease vasopressin secretion
C. inhibit the osmoreceptors and increase vasopressin secretion
D. inhibit the osmoreceptors and increase vasopressin secretion
E. cause no change in vasopressin secretion
A. stimulate the osmoreceptors and increase vasopressin secretion

Remember that if vasopressin increases, then more water will be reabsorbed by the kidney. This would be an appropriate response to an increase in osmolarity. The osmoreceptors secrete vasopressin, and would be stimulated by an increase in osmolarity.
25. An individual is in steady state balance for Na+ (intake = excretion).

Na + intake - 100 mM/day
GFR - 170 L/day
Urine flow - 1 L/day
Plasma [Na+] – 145 mmol/L

Find:
Filtered load Na+: (mM/day)
Clearance Na+:
Fraction Na+ Excreted:
25.
Steady state balance (intake = excretion).

Filtered load
Na+ : 24650 mM/day

Filtered load = (GFR)* plasma[Na+]
= 170L/day * 145mM/L
= 24650 mM/day
Since the individual is in Na+ balance, the excretion rate must be 100mM/day (the same as the intake).

Clearance Na+ - 690 mL/day

Clearance = (urine excretion rate Na+)/ plasma [Na+]
= 100 mM/day / .145 mM/L
= 690 mL/day

Fraction Na+ excreted – 0.4%


Urine excretion rate = 100mM/day ( this comes from being in balance with the Na+ intake) Plasma[Na+] = given as 145mmol/L

Clearance = 690mL/day

Fraction Na+ excreted = (urine excretion rate Na+)/ Filtered load [Na+]

= 100 mM/day / 24650 mM/day
= 0.4%
26. An individual has just eaten a large bag of very salty Doritos, without drinking any water. The resulting
disturbance in body fluids would be best described as:

A. hypoosmotic dehydration
B. hyperosmotic overhydration
C. hyperosmotic dehyrdration
D. hypoosmotic overhydration
E. isoosmotic dehydration
B. hyperosmotic overhydration

The Doritos lunch is similar to the example on page 12 of your lecture notes – the addition of a hypertonic
solution (more salt than wate)r to the ECF. Since the total body solute has increased, but the total body water has not, the osmolality would increase (osmolality = total body solute/ total body water). There will also be a shift of water from intracellular to extracellular compartment.
27. For this same individual, what would be the effect on hormone secretion?

A. aldosterone would increase
B. vasopressin will increase
C. ANP will decrease
D. renin will increase
E. both ANP and aldosterone will increase
B. vasopressin will increase

There are two changes in this individual which will be regulated: the increased osmolarity will stimulate
the secretion of ADH, and stimulate thirst, so that more water will be reabsorbed, and the individual will also take in water. At the same time, the change in ECF volume will activate the multiple sensors related to ECF volume and blood pressure, resulting in a decrease in the renin-angiotentinII-aldosterone system. This, in turn, will tend to decrease Na+ reabsorption. Remember, that when looking at the effect of changes in ECF volume, you expect
renin, angiotensin II and aldosterone to all vary in the same direction – all either increase or decrease. The
exception to this is when you are looking at the effect of K+ on aldosterone specifically. You also expect ANP to vary in the opposite direction from the renin-angiotensinII-aldosterone system.
28. The decrease in Na+ reabsorption by proximal tubules that results from an increased mean arterial pressure is referred to as:

A. osmotic diuresis
B. autoregulation
C. GFR
D. tubulo-glomerular feedback
E. pressure natriuresis
E. pressure natriuresis

Pressure natriuresis is the decreased Na+ reabsorption with increasing hydrostatic pressure. The increased hydrostatic pressure reduces the net forces favoring reabsorption in the peritubular capillaries
29. An individual who cannot secrete ADH (diabetes insipidus) takes in 800mOsm solute/day. If the urine she can excrete has an osmolarity of 80mOsm/L, what is the minimum volume of urine she would need to excrete each day in order to be in steady state balance (solute intake = solute excretion)
29. 10L/day.
concentration = amt/volume,

so the volume needed would be (amt)/(concentration)
= 800mOsm/day / 80mOsm/L
= 10L/day.

This is a lot. People with this condition are usually advised to limit their salt intake.
30. A child has suffered for several days with vomiting and diarrhea, and has lost 2Kg of ECF fluid. Her plasma [Na+] is now 130mmol/L. What effect will this illness have on the following (compared to the period before the illness):

Aldosterone secretion: (↑, ↓, or no change)

ADH secretion: (↑, ↓, or no change)

Plasma [Na+]: (↑, ↓, or no change)

ANP secretion: (↑, ↓, or no change)

Sense of thirst: (↑, ↓, or no change)
Aldosterone secretion: Increase

The decrease in extracellular fluid will stimulate secretion of the renin-angiotensinII- aldosterone system,

ADH secretion: Increase

ADH secretion will increase because of the effect of angiotensin II and baroreceptive
stimulation.

Plasma [Na+]: No change

The fluid lost is extracellular, isotonic, and will therefore have no effect on plasma [Na]+, or plasma osmolality.

ANP secretion: Decrease

The decrease in extracellular fluid will stimulate secretion of the renin-angiotensinII- aldosterone system, and decrease the secretion of ANP

Sense of thirst: Decrease

The loss of isotonic fluid in diarrhea is similar in effect to the loss of plasma during hemorrhage.
renin secretion will increase in conditions that require?
an increase in vasoconstriction and an increase in blood pressure.
ANP does what to renin secretion?
inhibits
ANP inhibits renin secretion, so a decreased level of ANP would be the same as?
a decreased level of inhibition, and the renin secretion would increase.
ANP inhibits renin secretion, so a decreased level of ANP would be the same as …….. and the renin secretion would _______.
a decreased level of inhibition

increase.
renin is secreted by?
the juxtaglomerular cells.
Renin is the enzyme that is part of the cascade of events leading to _______, and will increase under conditions in which ………… have decreased.
angiotensin II

blood pressure, or extracellular volume
Direct stretch of the JG cells will do what to rennin?
decrease renin (direct stretch is another result of high pressure)
An increase in mean arterial blood pressure would do what to rennin?
decrease renin secretion, not increase it.

Osmolality per se has no direct effect on renin.
What enhances sodium reabsorption, particularly in the distal tubule and collecting duct.
Aldosterone
Note that normally, renin and aldosterone levels should either both increase, or both decrease, since?
renin catalyzes the formation of angiotensin II, and angiotenin II stimulates the secretion of aldosterone.

Rennin ~~> angiotensin II, ~~> secretion of aldosterone
The descending loop of Henle is water permeable, but not ___ permeable.
salt
The tubular fluid first becomes concentrated as it passes through the _________, but in the ascending loop sodium is actively transported to an even greater degree, and the fluid becomes ______.
descending loop
hypoosmotic.
Water and salt are both reabsorbed to the same degree by the proximal tubule, so this fluid is _______ compared to plasma.
isosmotic
Water is never secreted in the?
descending loop
ADH increases water permeability in?
the late distal tubule.
Microvilli are prominent only in the?
proximal tubules
Glucose and other nutrients are transported only in?
the proximal tubules.
there should be no glucose in the tubular fluid once it leaves the?
proximal tubule
Diuretics act by?
blocking Na+ reabsorption
With Diuretics, the transporter in the TALH is different from that in the collecting tubule, so the diuretic would ____ _____ Na+ transport in the TALH, or water reabsorption in the proximal tubule.
not affect
Diuretics that act on cells of the collecting tubule would or would not have an significant effect on daily Na+ excretion?
Would

Although the percentage of filtered Na+ reabsorbed in the collecting duct may be small, the overall effect on Na+ excretion, and therefore ECF volume, is significant
Normally, the tonicity of the tubular fluid as it just enters the collecting tubule is always hypotonic.
The filtrate becomes diluted in the ascending loop of Henle, and by the time it reaches the late distal tubule, it has an osmolality less than that of plasma.
From there, the filtrate can increase in osmolality, but only if?
Vasopressin/ ADH is present, and water is reabsorbed.
The cortical nephrons do not contribute to the formation of concentrated urine because?
the concentrating mechanism requires a hyperosmotic interstitium, created by solute transport in the
loops of Henle of the juxtamedullary nephrons.
ADH stimulates the synthesis of water channels in?
the late distal tubule and collecting ducts.
The water channels in the proximal tubules are always present (constitutive), and do not depend on _________ in any way.
the level of ADH.
What will have no effect on the reabsorption of water in the proximal tubules.
ADH
What is the avg. percent of the the reabsorption of water in the proximal tubules?
which is normally about 65-70%.
The primary difference between diuresis and antidiuresis is in the?
osmolarity of the fluid in the collecting tubules.
if vasopressin increases, what happens to water?
more water will be reabsorbed by the kidney
The osmoreceptors secrete ________ and would be stimulated by ......
Vasopressin

an increase in osmolarity.
In the addition of a hypertonic solution (more salt than water) to the ECF. What happens to total body solute, total body water, osmolality & shift of water?
Since the total body solute has increased, but the total body water has not, the osmolality would increase (osmolality = total body solute/ total body water). There will also be a shift of water from intracellular to extracellular compartment.
An individual has just eaten a large bag of very salty Doritos, without drinking any water. The resulting disturbance in body fluids would be best described as hyperosmotic overhydration

For this same individual, what would be the effect on hormone secretion?
There are two changes in this individual which will be regulated:

the increased osmolarity will stimulate
the secretion of ADH, and stimulate thirst, so that more water will be reabsorbed, and the individual will also take in water.

At the same time, the change in ECF volume will activate the multiple sensors related to ECF volume and blood pressure, resulting in a decrease in the renin-angiotentinII-aldosterone system. This, in turn, will tend to decrease Na+ reabsorption.
Remember, that when looking at the effect of changes in ECF volume, you expect what
Items to all vary in the same direction – all either increase or decrease.
renin, angiotensin II and aldosterone
Remember, that when looking at the effect of changes in ECF volume, you expect what
Items to all vary in the same direction – all either increase or decrease. The exception to this is when you are looking at ………. and you also expect …..
the effect of K+ on aldosterone specifically.

ANP to vary in the opposite direction from the renin-angiotensinII-aldosterone system.
Pressure natriuresis is?
the decreased Na+ reabsorption with increasing hydrostatic pressure.
The increased hydrostatic pressure by Pressure natriuresis reduces?
the net forces favoring reabsorption in the peritubular capillaries
Water and salt loads can vary?
independently
Salt intake varies daily, but normal plasma osmolality is?
285-295 mOsm/L
Plasma osmolality is primarily due to Na and associated anion, so can be estimated from?
P[na]: ~ 2 * P[na]
Levels of daily salt intake recommended for high blood pressure patients is?
< 2400mg/day (104mmol);
What is the average american Levels of daily salt diet?
varies widely
What effect could the daily intake have on ECF volume if 179mmol = amount of Na+ found in 1.2 L ECF
Increase ECF volume
How is sodium balanced:
intake= excretion
Na+ determines ____ volume;
ECF
Na+ reabsorption is primarily regulated by?
ECF volume sensors
How is water intake balanced?
intake must balance water loss
What is the average water intake for an adult?

Fluid
In food
Metabolically produced from food
Total
1200 mL/day Fluid
1000 mL/day In food
300 mL/day Metabolically produced from food
2500 mL/day Total
What is the average water output intake for an adult?

Insensible
Sweat
Feces
Urine
Total
700 mL/day Insensible
100 mL/day Sweat
200 mL/day Feces
1500 mL/day Urine
2500 mL/day Total
During heavy exercise, water output can exceed 6700 mL/day. This must be compensated for by both ………….. because there is……?
urinary outflow, and water intake,

an obligate urinary water loss of about 500ml/day
Why is there n obligate urinary water loss of about 500ml/day?
Required to eliminate waste like urea
What is the max urine osmolarity?
1200 mOsm/L
Water generates how much mOsm/day of waste?
600 mOsm/day
What determines osmolality (water reabsorption)?
Water
Filtered load [Na+] = ?
GFR * P[Na+]
% of filtered load of reabsorbed Na+ along the nephron
Proximal tubule
65-70
Thin Descending limb
0
Thin ascending limb
5
TALH
20
Distal convoluted
Tubule
4
Collecting tubules
1-4
% of filtered load of reabsorbed water along the nephron
Proximal tubule
65-70
Thin Descending limb
15
Thin ascending limb
0
TALH
0
Distal convoluted
Tubule
0
Collecting tubules
5-14
General rules of relative reabsorption of water along the nephron:
Water movement is always passive

Water follows solute (if the cells are permeable to water)

Thin descending limb and proximal tubules are
always permeable

Vasopressin regulates collecting tubule permeability
Water movement is always?
passive
Water follows solute if?
the cells are permeable to water
Thin descending limb and proximal tubules are
always permeable to?
water
Vasopressin regulates what for water?
collecting tubule water permeability
General rules of relative reabsorption of Na+: along the nephron:
• Basolateral ATPase (Na+/K+) establishes an electrochemical gradient driving reabsorption from the tubular lumen into the cell.

• Na+ enters the cell from the lumen via

• Na+ reabsorption is regulated by Angiotensin II, Aldosterone, & ANP
What establishes an electrochemical gradient driving Na+ reabsorption from the tubular lumen into the cell.
Basolateral ATPase (Na+/K+)
Na+ enters the cell from the lumen via what 4 ways?
1. Na+ channels
2. Na+/H+ antiport
3. Na+/x symport
4. leaky tight junctions
• Na+ reabsorption is regulated by what 3 ways:
Angiotensin II (proximal tubule)

Aldosterone (primarily collecting tubule)

ANP (atrial natriuretic peptide; inhibits Na+ reabsorption)
Na+ reabsorption in the proximal tubule is regulated by?
Angiotensin II
Na+ reabsorption in the primarily collecting tubule is regulated by?
Aldosterone
What inhibits Na+ reabsorption in the nephron?
ANP (atrial natriuretic peptide)
Na+ cotransported with ……and in exchange for….?
nutrients (symports, glucose e.g.)

H+ (antiport)
(requires Carbonic Anhydrase)
Na+ cotransportation processes are driven primarily by?
the primary active transport of the basolateral Na+/K+ ATPase.
Water in the proximal tubule moves along the osmotic gradient through ___________ and via ….
the cells (constitutively open aquaporins)

paracellular transport.
Water is reabsorbed by and with?
bulk flow,

reabsorption of solutes.
Water reabsorption in the proximal tubule is?
isoosmotic
proximal tubule cells are always permeable to water due to ……. and water is able to pass through
(aquaporins – water channels),

tight junctions.
Normally: if plasma [Na+] = 145mmol/L

at beginning of proximal tubule [Na+]= ?

At end of proximal tubule [Na+] = ?
at beginning of proximal tubule [Na+]= 145mmol/L

At end of proximal tubule [Na+] = 145mmol/L
In the proximal tubule, What increases Na+ reabsorption by increasing Na/K ATPase (and water)?
Angiotensin II
In the proximal tubule, Angiotensin II increases what by increasing Na/K ATPase (and water)?
Na+ reabsorption
In the proximal tubule, Angiotensin II increases Na+ reabsorption by?
increasing Na/K ATPase (and water)
What are the Starling forces at the peritubular capillaries?
Low hydrostatic pressure
High Pi pressure

Both favor reabsorption
The proximal tubule is the primary sight of?
reabsorption of solutes
The proximal tubule is the primary sight of reabsorption of solutes. What would happen if a solute were freely filtered, but could not be reabsorbed by the proximal tubule cells?
Decreased reabsorption
Increased water excretion
What would happen if an individual had high plasma concentration of glucose?
Type I diabetes
Very high plasma glucose
Filtered load is greater than Tm

Example Polyuria
At the end of the proximal tubule, about 30-35% ________ ___ leaves proximal tubule and enters loop of Henle
filtered Na+
At the end of the proximal tubule, what is the % of filtered Na+ leaves proximal tubule and enters loop of Henle
about 30-35%
% of filtered Na+ is fairly constant, over ....
a wide range of GFR
At the end of the proximal tubule, if ECF volume increases, and GFR increases what happens?
Increased rate of delivery of NaCl

60% - 65% in proximal tubule

(PT balance)
Tubular segments have different permeabilities to?
water and Na+
What is the descending thin loop of Henle permeability of Na and water?
Almost impermeable to Na,
but permeable to water
The interstitium of the descending thin loop of Henle
Has what type of osmolarity that creates the osmotic gradient for water movement from the lumen, into the cells and interstitium
hyperosmotic
The interstitium of the descending thin loop of Henle
is hyperosmotic creating what for water movement from the lumen, into the cells and interstitium.
the osmotic gradient
In the descending thin loop of Henle, What mainly happens?
water reabsorption

increased concentration of Na and Cl( and any other solute) within the tubular fluid.
Water is reabsorbed, but not Na+ in the descending thin loop of Henle, so there is an increase of what in the luminal fluid?
increased concentration of Na+
In the ascending thin loop of Henle, What is the permeability of Na and water?
impermeable to water,
permeable to Na+
Since Na+ concentration had increased in the descending loop, now the Na+ in the ascending loop of Henle can?
move passively out of the tubule fluid into the interstitium
What are the 2 transporters in TAHL?
Apical transporter of NKCC (Na+, K+, 2Cl- cotransporter) w/ apical K+ channel

paracellular transport of Na+ w/ apical Na+/H+ exchange
The K+ of NKCC is _________ and how?
recycled

enters through the NKCC transporter, but exits back to the lumen through the apical K+ channel
Why is recycling K+ in TAHL helpful?
Helps run the symport
In the TAHL, What is the normal concentration of K+ in ECF?
???
In TAHL, there is …….. of Na+, and an apical
paracellular transport

Na+/H+ exchange
What is the TAHL permeability of Na+ and water?
impermeable to water,
permeable to Na+
Loop of Henle as a whole has reabsorbed more solute than fluid, so the TALH is called?
the diluting segment
the TALH is called the diluting segment, and fluid leaving this segment, and entering the distal tubule, has what osmolarity?
hypoosmotic
The TAHL has ______ molarity then plasma
lower
What does the Macula Densa do?
senses the outcome
(delivery rate of NaCl)
If there is an increase of GFR when the rate of NaCl in fluid leaving the proximal tubule will?
Increase
If the rate of NaCl in fluid leaving the proximal tubule increases, then the delivery of NaCl to the macula densa will?
Increase
If the delivery of NaCl to the macula densa increases, then the …….. activates.
Tubuloglomerular Reflex
What happens if the Tubuloglomerular Reflex of the Macula Densa activates?
Vasoconstriction of afferent arteriole which lowers the GFR
Fluid entering Distal convoluted tubule (DCT)
Has what type of osmolarity?
hypoosmotic
Distal convoluted tubule (DCT) of does what with filtered NaCl
Reabsorbs ~ 5%
Distal convoluted tubule (DCT) uses what type of transport to reabsorb filtered NaCl
1. Na+ / Cl – cotransporter (TSC1)
What is the Distal convoluted tubule (DCT) permeability of Na+ and water?
little H2O reabsorption

permeable to Na+
What is the Collecting Duct (CD)
permeability of Na+ and water?
permeable to Na+ & H2O
Distal convoluted tubule (DCT) uses what type of transport to reabsorb filtered NaCl
Na Channels (ENaC)
K+ Channels
Medullary interstitium is hyperosmotic, so increasing permeability in CT and CD will allow water to enter interstitium, and will?
increase the osmolality of the tubular fluid
What does Aldosterone do for Na+ reabsorption in the CD?
regulates by increasing the number of Na+ channels, and the Na/K ATPase.
How would you increase the number of Na+ channels, and the Na/K ATPase in the CD?
Add aldosterone
Increasing aldosterone levels in the CD will increase what?
Na+ reabsorption.
What can blocks the aldosterone effect on Na+ channels in the CD?
ANP
What does aldosterone do for K+ reabsorption in the CD?
increases K+ secretion
Water reabsorption in the CD is impermeable, unless there is?
Vasopressin (ADH, AVP).
What does Vasopressin do for water channels?
Vasopressin regulates the insertion of water channels.
Water reabsorption only in the presence of?
vasopressin (ADH)
In the CD of a nephron, water permeability is regulated by?
vasopressin.
In the CD of a nephron, water permeability is regulated by vasopressin. How is this done?
Vasopressin binds to the V2 receptor on the basolateral membrane.

This is coupled to a Gs protein, resulting in cAMP, increased transcription of genes for aquaporin-2, and increased formation and insertion of aquaporin-2 channels.

These permit water to enter the cell. (Water can always exit at the basolateral side, because that membrane is always permeable to water).
Water can always exit the CD of a nepthron at the ______ side, because that membrane is always permeable to water
basolateral
During water reabsorption in the CD, Vasopressin of a nephron binds to the ________ on the basolateral membrane
V2 receptor.
During water reabsorption in the CD, Vasopressin of a nephron binds to the V2 receptor on the basolateral membrane, what happens
The V2 receptor is coupled to a Gs protein, resulting in:
- cAMP,
- increased transcription of genes for aquaporin-2,
and
- increased formation and insertion of aquaporin-2 channels.
During water reabsorption in the CD, Vasopressin of a nephron binds to the V2 receptor on the basolateral membrane and is coupled to a Gs protein. This results in?
resulting in cAMP

increased transcription of genes for aquaporin-2,

and

increased formation and insertion of aquaporin-2 channels.
Fluid entering and leaving the Distal convoluted tubule (DCT). Has what type of osmolarity?
Inside:
Medullary interstitium is hyperosmotic, so increasing permeability in CT and CD will allow water to enter interstitium, and will increase the osmolality of the tubular fluid

Interstitium is hyperosmotic, so water will be reabsorbed as long as the water channels are present

Outside:
Final urine excreted is

Hypoosmotic if no vasopressin is present

Hyperosmotic if vasopressin is present
Vasopressin controls about what % of the total water reabsorption
20
Cortical and medullary collecting tubules reabsorb about 5-7% of the filtered load of Na+, compensating for?
daily fluctuations in diet and Na+ excretion.
What are the Intercalated cells of the Collecting Ducts (CD)?
1. H+ secretion, HCO3- reabsorption.
2. Potassium reabsorption.
Among the two Intercalated cells of the Collecting Ducts (CD), Which is responsible for acid/base balance?
H+ secretion, HCO3- reabsorption.
What happens during the H+ secretion, HCO3- reabsorption (the Intercalated cells) of the Collecting Ducts (CD)?
- Hydrogen and bicarbonate formed from water
and carbon dioxide in the cell (carbonic anhydrase).

- Bicarbonate returns to the circulation
by Cl-/HCO3- exchange at basolateral membrane,

- H+ is secreted into the lumen by H+ ATPase.

- Process is stimulated by academia
What is formed during the H+ secretion, HCO3- reabsorption (the Intercalated cells) of the Collecting Ducts (CD)?
Hydrogen and bicarbonate formed from water
and carbon dioxide in the cell (carbonic anhydrase).
During the H+ secretion, HCO3- reabsorption (the Intercalated cells) of the Collecting Ducts (CD), what happens to bicarbonate?
Bicarbonate returns to the circulation by Cl-/HCO3- exchange at basolateral membrane
During the H+ secretion, HCO3- reabsorption (the Intercalated cells) of the Collecting Ducts (CD), what happens to H+?
H+ is secreted into the lumen by H+ ATPase.
The H+ secretion, HCO3- reabsorption of the Collecting Ducts (CD) process is stimulated by?
academia
During the Potassium reabsorption (the Intercalated cells) of the Collecting Ducts (CD), Cortical collecting tubule normally secretes potassium, but under circumstances of potassium depletion, net reabsorption occurs mediated by?
K+ATPase of the intercalated cells
Hormonal regulation of Na+ & water reabsorption
in the Proximal tubule is regulated by?
Angiotensin II
How does Angiotensin II
affect the proximal tubule?
Increased Na+ & water reab.

Fluid is Isoosmotic
Hormonal regulation of Na+ & water reabsorption in the Collecting tubules is regulated by what three items?
aldosterone

ANP

Vasopressin
How does aldosterone
affect the Collecting tubules?
Increase Na+ reabsorption in collecting duct
Hormonal regulation of Na+ & water reabsorption in the Collecting tubules is regulated by?
ANP
How does ANP affect the Collecting tubules?
Inhibits the effects of aldosterone
Hormonal regulation of Na+ & water reabsorption in the Collecting tubules is regulated by?
Vasopressin
How does Vasopressin affect the Collecting tubules?
Increases water reabsorption in collecting duct
What do Diuretics do?
They interfere w/ Na+ reabsorption
What would happen if you took a diuretic?
Decrease in ECF volume and then a decrease in blood pressure
Transporters are …………., subject to …………………, and the target of what?
molecularly distinct

different disorders

different drugs - diuretics
Diuretics have different side effects, depending on?
the molecular target
4 Renal mechanisms for excreting dilute or concentrated urine
1. Water follows solute in the proximal tubule, but water and solute are regulated separately in other tubule
segments
2. The interstitium of the medulla (not the cortex) has a steep gradient of solute
3. Urea recycles from medullary interstitium to tubular lumen and back to interstitium and adds to the solute
gradient of the interstitium
4. The vasa recta helps maintain the solute gradient of the medullary intersitium
Water follows solute in the proximal tubule, but water and solute are regulated how in other segments of the nephron?
Separately
The interstitium of the medulla (not the cortex) has a _____ gradient of solute
Steep
Urea recycles from ….. to…..then and adds to?
medullary interstitium to tubular lumen and back to interstitium

the solute gradient of the interstitium
The ____ ______ helps maintain the solute gradient of the medullary intersitium
vasa recta
In osmotic gradients in the medullary interstitium,
All renal corpuscles are in the ?
cortex
In osmotic gradients in the medullary interstitium,
Total loop of Henle is in …… for?
medulla

juxta-medullary nephrons
In osmotic gradients in the medullary interstitium,
What is in the medulla for juxta-medullary nephrons?
Total loop of Henle
In osmotic gradients in the medullary interstitium,
What is in the medulla for cortical nephrons?
TALH
The Interstitial fluid of the Cortex is what type of osmolarity?
Isoosmotic
The Interstitial fluid of the Medulla is what type of osmolarity?
hyperosmotic,

following a gradient of 300mosm (at cortical-medullary Junction) to as much as 1400mosm at apex of medulla. (region closest to the calyx)
Vasa recta blood comes from the ?
the efferent arteriole
Vasa recta blood pathway from efferent arteriole to veins in the Cortex:
the efferent arteriole ~~> arcurate artery ~~> interlobar artery ~~> capillary of the vasa recta ~~> interlobar veins ~~> arcurate vein ~~> Renal Vein
Vasa recta blood pathway does not just pass through the medulla, but follows:
the loop of Henle, and returns back to the cortex
What is Water Diuresis?
Increased urine excretion resulting from low vasopressin or Absence of ADH/Vasopressin
With water diuresis in the Proximal tubule, name 3 facts.
Permeable to water and salt;
interstitium and tubular fluid is isoosmotic,
With water diuresis in the Proximal tubule, What is permeable?
Permeable to water and salt;
With water diuresis in the Descending loop of Henle, What is permeable and how does it pass through?
Permeable to water, and passing through a hyperosmotic interstitium, so water leaves the tubular lumen.

Less permeable to salt and urea.
With water diuresis in the Descending loop of Henle, Tubular fluid becomes ________, and at bend ~= _________ .
hyperosmotic
interstitium
With water diuresis in the Descending loop of Henle, Solutes of tubule differ from interstitium. They are?
NaCl lumen
Urea lumen

NaCl lumen (greater than) interstitium

Urea lumen (less than) interstitium
With water diuresis in the Descending loop of Henle, Solutes of tubule differ from interstitium.

NaCl lumen _____ interstitium
Greater than
>
With water diuresis in the Descending loop of Henle, Solutes of tubule differ from interstitium. How?

Urea lumen ___ interstitium
Less than
<
Where in the nephron is H2O permeable?
Proximal tubule - PT
Descending Loop of Henle - DLOH
Where in the nephron are solutes most concentrated?
at bend of the Descending Loop of Henle - DLOH
Where in the nephron is urea facilitated diffused back into the nephron
Ascending Loop of Henle - ALH

Medullary Collecting Duct - MCD
Where in the nephron is NaCl permeable?
Ascending Loop of Henle – ALH

Thick Ascending Loop of Henle - TALH

And to the first bend of the Distral Tube – DT
Where in the nephron is more Na+ and H2O absorbed than usual?
The first bend of the Distral Tube – DT
Where in the nephron is the solutes more dilute than any other time?
The first bend of the Distral Tube – DT
Where in the nephron is water impermeable?
Cortical Collecting Duct - CCD

Medullary Collecting Duct - MCD
With water diuresis in the Ascending thin loop of Henle - ALH, name 3 facts.
Impermeable to water. Permeable to salt and urea,

concentration gradients promote NaCl exit from lumen, and urea entrance into lumen.

Net flux of NaCl > that of urea, so there is a net loss of solutes, and the fluid is diluted
With water diuresis in the Ascending thin loop of Henle - ALH, What is permeable?
Impermeable to water. Permeable to salt and urea,
With water diuresis in the Ascending thin loop of Henle - ALH, concentration gradients promote?
NaCl exit from lumen, and urea entrance into lumen.
With water diuresis in the Ascending thin loop of Henle - ALH, Net flux of NaCl (G/S/L) that of urea, so there is….?
Greater than (>)

a net loss of solutes, and the fluid is diluted
With water diuresis in the thick ascending loop of Henle (TALH), What is permeable?
Impermeable to water and urea.
With water diuresis in the thick ascending loop of Henle (TALH), there is active reabsorption of Na+, so fluid becomes?
hypoosmotic
With water diuresis in the thick ascending loop of Henle (TALH), name 2 facts.
Impermeable to water and urea.

there is active reabsorption of Na+, so fluid becomes hypoosmotic
With water diuresis in the Distral Tube – DT,
name 2 facts.
Impermeable to water

fluid remains hypoosmotic
With water diuresis in the Ascending thin loop of Henle - ALH, What is permeable?
Impermeable to water
With water diuresis in the Cortical collecting duct – CCT, name 3 facts.
Active reabsorption of NaCl, but impermeable to urea.

Impermeable to water in the absence of ADH.

Fluid becomes more hypoosmotic
With water diuresis in the Cortical collecting duct – CCT, What is permeable?
Active reabsorption of NaCl, but impermeable to urea.

Impermeable to water in the absence of ADH.
With water diuresis in the Cortical collecting duct – CCT, What is the Osmolarity?
Fluid is more hypoosmotic
With water diuresis in the Medullary collecting duct – MCD, name 3 facts.
Active reabsorption of NACl continues.

Slight permeability to water and urea, so some slight reabsorption of water even without ADH

Final urine excretion is ~ 50mOsm/L
With water diuresis in the Medullary collecting duct – MCD, What is permeable?
Active reabsorption of NACl continues.

(Slight permeability to water and urea, so some slight reabsorption of water even without ADH)
With water diuresis in the Medullary collecting duct – MCD, What is the Osmolarity?
Trying to keep Hypertonic
The Processes of the TALH in step 4 allow which step to proceed?
The Na+ from step 4 allows H2O to leave DLH in Step 2 (by Gradient)
Urea is freely filtered, and reabsorbed in?
the proximal tubule (~50% filtered load)
Urea is secreted in the?
thin loop of Henle, (~filtered load)
Urea concentration = formula
amount/volume
The volume of fluid in the TLH has _________ from its travel from the proximal tubules
decreased
concentration of urea entering ATLH (G/S/L) concentration in proximal tubule
Greater than (>)
What happens to the Urea in the Collecting duct?
urea is reabsorbed, and contributes to the hyperosmolality of the medulla
What contributes to the hyperosmolality of the medulla?
Urea in the Collecting duct
Medullary gradient is % NaCl and ___ % urea.
50% NaCl and 50% urea.
Diabetes insipidus – insipidus means?
Tasteless
What is Diabetes insipidus?
posterior pituitary defect
Diabetes insipidus results in ?
deficient vasopressin release.
What would be the outcome of someone with Diabetes insipidus?
Dilute urine

Up to 18 L a day
Where in the nephron is aquaporins available due to Vasopressin?
Cortical Collecting Duct - CCD
Medullary Collecting Duct - MCD
Summerize the first 5 Steps for diuresis?
Fluid entering the distal tubule is hypoosmotic. However, the NaCl reabsorbed in ascending loop (thin and thick) has increased the osmolality of the medullary interstitium. This gradient is steeper than that in the previous condition.
What is the sixth step for diuresis?
In the presence of ADH, water leaves the tubular lumen and enters the cortical interstitium (this interstitium has an osmolality of 300mOsm/L). However, because most of the NaCl has already been reabsorbed, urea makes a greater contribution to the solutes of the tubular lumen.
What is the osmolarity (#) of cortical interstitium?
this interstitium has an osmolality of 300mOsm/L
What is the seventh step for diuresis?
ADH increases water permeability, and water follows its osmotic gradient out of the tubular lumen.

In addition, urea follows its concentration gradient, form the lumen, into the interstitium.
Urine osmolality ranges from?
50mOsm/L (water diuresis) to 1200 mOsm/L (antidiuresis).
Urine volume ranges from?
the obligate loss of 500mL/day to about 18L
Why is the finding of isoosmotic urine in a patient a cause for alarm?
Suggest the kidneys aren’t working

Maybe there is a block at TALH
The vasa recta is crucial for maintaining?
the gradient
Blood entering the medulla would have the osmolality of systemic plasma

As blood passed through the medulla and the hyperosmotic interstitium, solute would enter the capillary due to ……….., and water would exit the capillary due to …..
concentration gradient

osmotic gradient
What would happen if the vasa recta were straight,
flowing through the medulla, instead of returning to the cortex?
“Straight vasa recta”:

Blood leaving the medulla would be hyperosmotic, and the osmotic gradient of the interstitium would be reduced causing “washed out”
What would happen if the vasa recta lacked the hairpin turn?
Hyperosmotic and loss of solute in interstitial fluid
causing “washed out
What are the steps of blood osmolarity of the Vasa recta with hairpin turn?
1. Blood entering has normal plasma osmolality. Solute enters capillary, and water exits capillary, along the descending length
2. Blood at papillary end has higher osmolality than plasma, but still less than interstitium
3. Blood reaches equilibrium with the interstitium in the ascending portion
4. Blood continues to flow, but is now hyperosmotic to interstitium, and solute will exit capillary, and water will enter capillary
5. Blood finally leaving medulla is somewhat hypertonic to plasma, but less so than in the first case. Also, more of the gradient has been preserved.
What are the steps of blood osmolarity of the Cortical Nephron with the Vasa Recta?
1. Very short loops of Henle
2. Peritubular capillaries act like the straight capillaries, and diminish the effect of any interstitial gradient
3. urine concentration is a function of juxtamedullary nephrons, not cortical nephrons.
An individual wishes to prepare ahead of time for a
marathon by overhydrating several days before the
race. Why is this a bad idea?
You would have a period of water loading

Diuretic ~~> reduced gradient
Water and salt load can vary?
independently
Variations in Na+ affect?
ECF volume
Variations in water affect?
osmolality
What affects ECF volume?
Variations in Na+
What affects osmolality?
Variations in water
What are the effects of Isoosmotic dehydration (blood loss)?
Decrease in ECF volume
No change is Osmolarity
What are the effects of Isoosmotic Overhydration (taking in isotonic saline)?
Increase in ECF volume
No change is Osmolarity
What are the effects of Hyperosmotic dehydration (sweat loss)?
Increase in Osmolarity
Decrease in ECF volume*

*Happens regardless w/ sweat loss
What are the effects of Hypoosmotic dehydration (sweat loss with water replaced)?
Decrease in Osmolarity
Decrease in ECF volume*

*Happens regardless w/ sweat loss
What are the effects of hyperosmotic overhydration (taking in hypertonic fluid)?
Increase in ECF volume
Increase in Osmolarity
What are the effects of hypoosmotic overhydration (taking in pure water)?
Increase in ECF volume
Increase in Osmolarity
If a patient’s test results show that they have a decrease in ECF volume and No change is Osmolarity, what is their Na+ and H20 homeostasis?
Isoosmotic dehydration
(blood loss)
If a patient’s test results show that they have an increase in ECF volume and no change is Osmolarity, what is their Na+ and H20 homeostasis?
Isoosmotic Overhydration
(taking in isotonic saline)
If a patient’s test results show that they have an decrease in ECF volume and increase in Osmolarity, what is their Na+ and H20 homeostasis?
Hyperosmotic dehydration (sweat loss)
If a patient’s test results show that they have an decrease in ECF volume and decrease in Osmolarity, what is their Na+ and H20 homeostasis?
Hypoosmotic dehydration
(sweat loss with water replaced)
If a patient’s test results show that they have an increase in ECF volume and increase in Osmolarity, what is their Na+ and H20 homeostasis?
hyperosmotic overhydration
(taking in hypertonic fluid)
If a patient’s test results show that they have a decrease in ECF volume and increase in Osmolarity, what is their Na+ and H20 homeostasis?
hypoosmotic overhydration
(taking in pure water)
What is the sensor specifically for total body Na+ homeostasis?
There is no sensor specifically for total body Na+.
There is no sensor specifically for total body Na+.
However, because Na+ is the primary cation in ECF, and therefore, the osmolarity of extracellular fluid changes in extracellular Na+ are
paralleled by changes in?
ECF
ECF = formula
plasma volume + interstitial volume
“blood volume is an important determinant of arterial pressure because it directly affects?
venous pressure,
venous return,
end-diastolic volume,
stroke volume,
and cardiac output”
What many sensors for ECF volume?
Multiple sensors for ECF volume
What are two types of sensors for ECF volume?
Systemic
&
Renal
What is the systemic sensor for ECF volume?
baroreceptors,
in high pressure (i.e. carotid sinus)
and low pressure (atrial) sites
Where are baroreceptors located?
baroreceptors, in high pressure (i.e. carotid sinus) and low pressure (atrial) sites
What are the Renal sensors for ECF volume?
JG cells (stretch sensitive),
Macula Densa cells (flow sensitive)
the JG cells of the Renal sensors for ECF volume
are ________ sensitive
stretch
the macula densa cells of the Renal sensors for ECF volume are_________ sensitive
flow
If the the JG cells of the Renal sensors for ECF volume increases its stretch, what happens?
Decrease in Renin
If the macula densa cells of the Renal sensors for ECF volume receive increased GFR, what happens?
Increased rate of NaCl delivered
What are the 5 effectors hormones of ECF volume:
• Renin –
• Aldosterone
• Angiotensin II
• Vasopressin (ADH) Increases water reabsorption in
• ANP
What are the facts of the effectors hormone Renin of ECF volume:
released by JG cells, results in an increase in angiotensin II
The effector hormone Renin is released by released by?
JG cells
The effector hormone Renin results in an increase in?
angiotensin II
What are the facts of the effectors hormone Aldosterone of ECF volume:
Increases the Na+ reabsorption in the collecting ducts.

Regulates 2% of filtered load

Aldosterone is secreted by the adrenal gland in response to angiotensin 2
The effector hormone Aldosterone increases?
the Na+ reabsorption in the collecting ducts.
The effector hormone Aldosterone regulates?
2% of filtered load
The effector hormone Aldosterone is secreted by?
the adrenal gland
Aldosterone is secreted by the adrenal gland in response to?
angiotensin 2
What are the facts of the effectors hormone Angiotensin II of ECF volume:
In addition to effect on aldosterone release, angiotensin II increases Na+ reabsorption in proximal tubules

Acts on efferent arterioles; high levels – acts on afferent and efferent arterioles

High levels - ↑ vasopressin release
The effector hormone Angiotensin II affects what?
aldosterone release
The effector hormone Angiotensin II increases?
Na+ reabsorption in proximal tubules
Normal levels of the effector hormone Angiotensin II acts upon what type of arterioles?
Acts on efferent arterioles
High levels of the effector hormone Angiotensin II acts on what type of arterioles?
afferent and efferent arterioles

Acts on efferent arterioles; high levels – acts on afferent and efferent arterioles
The effector hormone Angiotensin II increases?
vasopressin release
High levels the effector hormone, Angiotensin II will do what to vasopressin?
Increase vasopressin release
What are the facts of the effectors hormone Vasopressin (ADH) of ECF volume:
Increases water reabsorption in the collecting ducts

Regulates about 20% of the filtered load

Vasopressin is secreted by posterior pituitary in response to angiotensin 2 and other baroreceptor
mediated reflexes and in response to hypothalamic osmoreceptors
The effector hormone Vasopressin (ADH) increases?
water reabsorption in the collecting ducts
The effector hormone Vasopressin (ADH) regulates % of the filtered load?
about 20%
The effector hormone Vasopressin (ADH) is secreted by?
posterior pituitary
The effector hormone Vasopressin (ADH) is secreted by posterior pituitary in response to what two receptors?
angiotensin 2 & other baroreceptor
mediated reflexes
and hypothalamic osmoreceptors
What are the facts of the effector hormone ANP of ECF volume:
Atrial natriuretic peptide (atrial natriuretic factor)

Secreted by the heart in response to atrial stretch

Inhibits aldosterone action in the kidney; inhibits aldosterone release, and inhibits renin secretion

Inhibits vasopressin release
The effector hormone ANP is secreted by?
the heart in response to atrial stretch
The effector hormone ANP is secreted by the heart in response to?
atrial stretch
The effector hormone ANP inhibits what three things?
Inhibits aldosterone action in the kidney;

inhibits aldosterone release,
and inhibits renin secretion
The effector hormone ANP inhibits the release of?
vasopressin release
Vasopressin is usually controlled by?
Osmolarity
GFR is often constant due to?
autoregulation
Ex. Tubloglomerular Feedback from (MD)
Amount excreted = Formula
amt filtered – amt reabsorbed = Amount excreted
Amount filtered= P[x] * GFR
Another name for amount filtered is?
Filtered load
Decreases in GFR will decrease:
the filtered load, and the excretion of Na+
Reabsorption is a multi step process: explain the 3 steps.
water or solute must move from the tubular lumen into the interstitium, and then must move from the interstitium into the capillaries (peritubular or vasa recta).

Movement into the capillaries is regulated by Starling’s law, so that an increased hydrostatic pressure in the capillaries will reduce reabsorption.

An increase in arterial pressure decreases Na+ reabsorption in the capillaries
The movement into the capillaries during reabsorption is regulated by Starling’s law, so that?
an increased hydrostatic pressure in the capillaries will reduce reabsorption.
An increase in arterial pressure during reabsorption, does what to reabsorption?
the decreases Na+ reabsorption in the capillaries
Increased Sympathetic outflow in Baroreceptor reflexes will affect?
Arteriolar smooth muscle contraction (especially an afferent arteriolar)

GFR
Pressure naturesis
High pressure by itself will ______ Na+ excretion
increase
Low pressure by itself will ______ Na+ excretion
decrease
(I/D) of arteriol pressure ~>
(I/D) hydrostatic pressure ~> ??
Increase of arteriol pressure ~> Increase hydrostatic pressure ~> Na+ reabsorption
Increased Sympathetic outflow in Baroreceptor reflexes will directly innervate JG cells, by doing this what chain rxn starts?
sympathetic increase ~> increased renin
~> Angiotensin II ~> ANP ~ Vasopressin release
ANP is released from?
the heart
Increased Sympathetic outflow in Baroreceptor reflexes will have what effect?
Vasopressin release
What is the behavior of Sympathetic outflow in Baroreceptor?
thirst
What are the two influences of water homeostasis?
Osmolarity & extracellular fluid volume
What is the primary and secondary influence of water homeostasis?
Osmolarity & extracellular fluid volume
What is the equation for Osmolarity & extracellular fluid volume and Osmolarity & intercellular fluid volume?
Osmo / ECF = Osmo / ICF
Sensors, and mechanisms result in changes in _____ which regulates distal
nephron water reabsorption.
vasopressin (ADH),
Sensors, and mechanisms result in changes in vasopressin (ADH), which regulates?
Distal nephron water reabsorption.
Many variations in ECF involve loss or gain in?
both sodium and water.
How many sensors are involved in water homeostasis?
additional sensors (more than one)
Osmoreceptors shrink or swell and that affects?
mechanic sensitive ion channels
Osmoreceptors Sensors is located in the?
hypothalamus.
Sensors Osmoreceptors is located in the hypothalamus.

Pure water is distributed in all compartments
Add 1L pure water:

How much goes to ICF
How much goes to ECF
Where does most of the water go (ICF or ECF)
(based on typical relative volumes of ECF and ICF)
2/3 to ICF
1/3 to ECF
Most H2O goes to ICF
(based on typical relative volumes of ECF and ICF)
Pure water is distributed in all compartments.
Add 1L pure water:

This will cause a slight change in?
systemic blood pressure
Pure water is distributed in all compartments.
Add 1L pure water. This will cause a slight change in systemic blood pressure

However, there will be in ………. in osmolarity for all compartments
large change
Osmoreceptor reflex is located in?
The Hypothalamus
What triggers sense of thirst?
The two Osmosreceptors of the Hypothalamus
The Hypothalamus has how many sets of osmosreceptors?
2
What do osmosreceptors do?
• osmosreceptors regulate release of vasopressin (ADH)
Decreased osmolality which causes a decrease in vasopressin (ADH)
• second set osmoreceptors trigger thirst which will lead to water intake
How do the two Osmosreceptors of the Hypothalamus regulate release of vasopressin (ADH)?
Decreased osmolarity which causes a decrease in vasopressin (ADH)
What other factors that can increase or decrease vasopressin release
Hemodynamic factors and other factors
What Hemodynamic factors that can increase or decrease vasopressin release?
ECF volume expansion

ECF volume reduction
What does ECF volume expansion
of the Hemodynamic factors that can increase or decrease vasopressin release do?
Large changes – 10% change of ECF which decreases ADH
What does ECF volume expansion
of the Hemodynamic factors that can effect vasopressin release do?
Decrease ADH
What does ECF volume reduction of the Hemodynamic factors that can effect vasopressin release do?
Increase ADH
What are the others factors that can affect vasopressin release?
Nausea, anxiety/fear, nicotine, angiotensin II


ANP, Ethanol
What are the others factors that can increase vasopressin release?
Nausea, anxiety/fear, nicotine, angiotensin II
What are the others factors that can decrease vasopressin release?
ANP, Ethanol
What is the other effect that the others factors, ANP & Ethanol, that decrease vasopressin release?
Dehydration
What happens if you suffer from hypoosmotic overhydration (drinking pure water)?
Decreased reabsorption of water (esp. in CT)

Increased water excretion
What happens over time if you suffer from hypoosmotic overhydration (drinking pure water)?
Wash out or decrease gradient in medulla = diuresis
What happens if you suffer from hyperosmotic dehydration (Sweat with water replacement)?
Osmolarity increase

ECF volume decreased
if you suffer from hyperosmotic dehydration (Sweat with water replacement), how does Osmolarity increase?
Increase of Vasopressin ~> Increase of Thirst ~> Increase of Water reabsorption (decrease in Excretion)
if you suffer from hyperosmotic dehydration (Sweat with water replacement), how does ECF volume decrease?
Increase of Renin-angiotensin II-aldosterone
~> decrease Pressure natriuresis ~ > GFR (may or may not change) ~> increase in Na+ reabsorption
For large changes in ECF volume, restoring _____ has has priority over restoring ____ hypoosmotic dehydration during hypoosmotic dehydration
ECF volume
Osmolarity
For large changes in ECF volume, Why does restoring ECF volume have priority over restoring Osmolarity during hypoosmotic dehydration?
ECF volume will override osmolarity, and vasopressin will be released
Sweat lose w/ H2O replacement steps for decrease in osmolarity and ECF volume?
Decrease in osmolarity ~> increase in water loss ~~> decreases vasopressin

Decrease in ECF volume ~> increase in Na+ reabsorption

If increase in Na+ reabsorption is large enough, vasopressin will increase
Large disturbances of ECF volume incorporate ……. Regulation and example?
both Na+ and water

Example: Hemorrhage
What happens with ECF volume during a hemorrhage?
Loss of isotonic fluid volume from the extracellular compartment

Increased reabsorption of water and salt
If you decrease ANP, what happens?
Less inhibition of aldosterone

Less inhibition of Osmoreceptor