Physiology Osborn Renal Ps5: Na+ And Water Reabsorption

Front 1

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

Back 1

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.

Front 2

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

Back 2

11.E. all of the above

Front 3

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

Back 3

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.

Front 4

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

Back 4

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.

Front 5

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

Back 5

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

Front 6

The plasma in the vasa recta will be _______ similar to the interstitial fluid through which it passes in the medulla.

Back 6

hyperosmotic,

Front 7

When the blood exits the vasa recta, and enters the arcuate veins, it is still slightly _________.

Back 7

hyperosmotic.

Front 8

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

Back 8

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.

Front 9

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

Back 9

C. thick ascending loop of Henle

Front 10

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

Back 10

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

Front 11

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

Back 11

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.

Front 12

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

Back 12

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.

Front 13

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

Back 13

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.

Front 14

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.

Back 14

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.

Front 15

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

Back 15

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%.

Front 16

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

Back 16

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

Front 17

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

Back 17

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.

Front 18

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:

Back 18

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%

Front 19

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

Back 19

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.

Front 20

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

Back 20

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.

Front 21

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

Back 21

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

Front 22

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)

Back 22

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.

Front 23

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)

Back 23

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.

Front 24

renin secretion will increase in conditions that require?

Back 24

an increase in vasoconstriction and an increase in blood pressure.

Front 25

ANP does what to renin secretion?

Back 25

inhibits

Front 26

ANP inhibits renin secretion, so a decreased level of ANP would be the same as?

Back 26

a decreased level of inhibition, and the renin secretion would increase.

Front 27

ANP inhibits renin secretion, so a decreased level of ANP would be the same as …….. and the renin secretion would _______.

Back 27

a decreased level of inhibition

increase.

Front 28

renin is secreted by?

Back 28

the juxtaglomerular cells.

Front 29

Renin is the enzyme that is part of the cascade of events leading to _______, and will increase under conditions in which ………… have decreased.

Back 29

angiotensin II

blood pressure, or extracellular volume

Front 30

Direct stretch of the JG cells will do what to rennin?

Back 30

decrease renin (direct stretch is another result of high pressure)

Front 31

An increase in mean arterial blood pressure would do what to rennin?

Back 31

decrease renin secretion, not increase it.

Osmolality per se has no direct effect on renin.

Front 32

What enhances sodium reabsorption, particularly in the distal tubule and collecting duct.

Back 32

Aldosterone

Front 33

Note that normally, renin and aldosterone levels should either both increase, or both decrease, since?

Back 33

renin catalyzes the formation of angiotensin II, and angiotenin II stimulates the secretion of aldosterone.

Rennin ~~> angiotensin II, ~~> secretion of aldosterone

Front 34

The descending loop of Henle is water permeable, but not ___ permeable.

Back 34

salt

Front 35

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 ______.

Back 35

descending loop
hypoosmotic.

Front 36

Water and salt are both reabsorbed to the same degree by the proximal tubule, so this fluid is _______ compared to plasma.

Back 36

isosmotic

Front 37

Water is never secreted in the?

Back 37

descending loop

Front 38

ADH increases water permeability in?

Back 38

the late distal tubule.

Front 39

Microvilli are prominent only in the?

Back 39

proximal tubules

Front 40

Glucose and other nutrients are transported only in?

Back 40

the proximal tubules.

Front 41

there should be no glucose in the tubular fluid once it leaves the?

Back 41

proximal tubule

Front 42

Diuretics act by?

Back 42

blocking Na+ reabsorption

Front 43

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.

Back 43

not affect

Front 44

Diuretics that act on cells of the collecting tubule would or would not have an significant effect on daily Na+ excretion?

Back 44

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

Front 45

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?

Back 45

Vasopressin/ ADH is present, and water is reabsorbed.

Front 46

The cortical nephrons do not contribute to the formation of concentrated urine because?

Back 46

the concentrating mechanism requires a hyperosmotic interstitium, created by solute transport in the
loops of Henle of the juxtamedullary nephrons.

Front 47

ADH stimulates the synthesis of water channels in?

Back 47

the late distal tubule and collecting ducts.

Front 48

The water channels in the proximal tubules are always present (constitutive), and do not depend on _________ in any way.

Back 48

the level of ADH.

Front 49

What will have no effect on the reabsorption of water in the proximal tubules.

Back 49

ADH

Front 50

What is the avg. percent of the the reabsorption of water in the proximal tubules?

Back 50

which is normally about 65-70%.

Front 51

The primary difference between diuresis and antidiuresis is in the?

Back 51

osmolarity of the fluid in the collecting tubules.

Front 52

if vasopressin increases, what happens to water?

Back 52

more water will be reabsorbed by the kidney

Front 53

The osmoreceptors secrete ________ and would be stimulated by ......

Back 53

Vasopressin

an increase in osmolarity.

Front 54

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?

Back 54

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.

Front 55

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?

Back 55

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.

Front 56

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.

Back 56

renin, angiotensin II and aldosterone

Front 57

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 …..

Back 57

the effect of K+ on aldosterone specifically.

ANP to vary in the opposite direction from the renin-angiotensinII-aldosterone system.

Front 58

Pressure natriuresis is?

Back 58

the decreased Na+ reabsorption with increasing hydrostatic pressure.

Front 59

The increased hydrostatic pressure by Pressure natriuresis reduces?

Back 59

the net forces favoring reabsorption in the peritubular capillaries

Front 60

Water and salt loads can vary?

Back 60

independently

Front 61

Salt intake varies daily, but normal plasma osmolality is?

Back 61

285-295 mOsm/L

Front 62

Plasma osmolality is primarily due to Na and associated anion, so can be estimated from?

Back 62

P[na]: ~ 2 * P[na]

Front 63

Levels of daily salt intake recommended for high blood pressure patients is?

Back 63

< 2400mg/day (104mmol);

Front 64

What is the average american Levels of daily salt diet?

Back 64

varies widely

Front 65

What effect could the daily intake have on ECF volume if 179mmol = amount of Na+ found in 1.2 L ECF

Back 65

Increase ECF volume

Front 66

How is sodium balanced:

Back 66

intake= excretion

Front 67

Na+ determines ____ volume;

Back 67

ECF

Front 68

Na+ reabsorption is primarily regulated by?

Back 68

ECF volume sensors

Front 69

How is water intake balanced?

Back 69

intake must balance water loss

Front 70

What is the average water intake for an adult?

Fluid
In food
Metabolically produced from food
Total

Back 70

1200 mL/day Fluid
1000 mL/day In food
300 mL/day Metabolically produced from food
2500 mL/day Total

Front 71

What is the average water output intake for an adult?

Insensible
Sweat
Feces
Urine
Total

Back 71

700 mL/day Insensible
100 mL/day Sweat
200 mL/day Feces
1500 mL/day Urine
2500 mL/day Total

Front 72

During heavy exercise, water output can exceed 6700 mL/day. This must be compensated for by both ………….. because there is……?

Back 72

urinary outflow, and water intake,

an obligate urinary water loss of about 500ml/day

Front 73

Why is there n obligate urinary water loss of about 500ml/day?

Back 73

Required to eliminate waste like urea

Front 74

What is the max urine osmolarity?

Back 74

1200 mOsm/L

Front 75

Water generates how much mOsm/day of waste?

Back 75

600 mOsm/day

Front 76

What determines osmolality (water reabsorption)?

Back 76

Water

Front 77

Filtered load [Na+] = ?

Back 77

GFR * P[Na+]

Front 78

% of filtered load of reabsorbed Na+ along the nephron

Back 78

Proximal tubule
65-70
Thin Descending limb
0
Thin ascending limb
5
TALH
20
Distal convoluted
Tubule
4
Collecting tubules
1-4

Front 79

% of filtered load of reabsorbed water along the nephron

Back 79

Proximal tubule
65-70
Thin Descending limb
15
Thin ascending limb
0
TALH
0
Distal convoluted
Tubule
0
Collecting tubules
5-14

Front 80

General rules of relative reabsorption of water along the nephron:

Back 80

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

Front 81

Water movement is always?

Back 81

passive

Front 82

Water follows solute if?

Back 82

the cells are permeable to water

Front 83

Thin descending limb and proximal tubules are
always permeable to?

Back 83

water

Front 84

Vasopressin regulates what for water?

Back 84

collecting tubule water permeability

Front 85

General rules of relative reabsorption of Na+: along the nephron:

Back 85

• 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

Front 86

What establishes an electrochemical gradient driving Na+ reabsorption from the tubular lumen into the cell.

Back 86

Basolateral ATPase (Na+/K+)

Front 87

Na+ enters the cell from the lumen via what 4 ways?

Back 87

1. Na+ channels
2. Na+/H+ antiport
3. Na+/x symport
4. leaky tight junctions

Front 88

• Na+ reabsorption is regulated by what 3 ways:

Back 88

Angiotensin II (proximal tubule)

Aldosterone (primarily collecting tubule)

ANP (atrial natriuretic peptide; inhibits Na+ reabsorption)

Front 89

Na+ reabsorption in the proximal tubule is regulated by?

Back 89

Angiotensin II

Front 90

Na+ reabsorption in the primarily collecting tubule is regulated by?

Back 90

Aldosterone

Front 91

What inhibits Na+ reabsorption in the nephron?

Back 91

ANP (atrial natriuretic peptide)

Front 92

Na+ cotransported with ……and in exchange for….?

Back 92

nutrients (symports, glucose e.g.)

H+ (antiport)
(requires Carbonic Anhydrase)

Front 93

Na+ cotransportation processes are driven primarily by?

Back 93

the primary active transport of the basolateral Na+/K+ ATPase.

Front 94

Water in the proximal tubule moves along the osmotic gradient through ___________ and via ….

Back 94

the cells (constitutively open aquaporins)

paracellular transport.

Front 95

Water is reabsorbed by and with?

Back 95

bulk flow,

reabsorption of solutes.

Front 96

Water reabsorption in the proximal tubule is?

Back 96

isoosmotic

Front 97

proximal tubule cells are always permeable to water due to ……. and water is able to pass through

Back 97

(aquaporins – water channels),

tight junctions.

Front 98

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

at beginning of proximal tubule [Na+]= ?

At end of proximal tubule [Na+] = ?

Back 98

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

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

Front 99

In the proximal tubule, What increases Na+ reabsorption by increasing Na/K ATPase (and water)?

Back 99

Angiotensin II

Front 100

In the proximal tubule, Angiotensin II increases what by increasing Na/K ATPase (and water)?

Back 100

Na+ reabsorption

Front 101

In the proximal tubule, Angiotensin II increases Na+ reabsorption by?

Back 101

increasing Na/K ATPase (and water)

Front 102

What are the Starling forces at the peritubular capillaries?

Back 102

Low hydrostatic pressure
High Pi pressure

Both favor reabsorption

Front 103

The proximal tubule is the primary sight of?

Back 103

reabsorption of solutes

Front 104

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?

Back 104

Decreased reabsorption
Increased water excretion

Front 105

What would happen if an individual had high plasma concentration of glucose?

Back 105

Type I diabetes
Very high plasma glucose
Filtered load is greater than Tm

Example Polyuria

Front 106

At the end of the proximal tubule, about 30-35% ________ ___ leaves proximal tubule and enters loop of Henle

Back 106

filtered Na+

Front 107

At the end of the proximal tubule, what is the % of filtered Na+ leaves proximal tubule and enters loop of Henle

Back 107

about 30-35%

Front 108

% of filtered Na+ is fairly constant, over ....

Back 108

a wide range of GFR

Front 109

At the end of the proximal tubule, if ECF volume increases, and GFR increases what happens?

Back 109

Increased rate of delivery of NaCl

60% - 65% in proximal tubule

(PT balance)

Front 110

Tubular segments have different permeabilities to?

Back 110

water and Na+

Front 111

What is the descending thin loop of Henle permeability of Na and water?

Back 111

Almost impermeable to Na,
but permeable to water

Front 112

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

Back 112

hyperosmotic

Front 113

The interstitium of the descending thin loop of Henle
is hyperosmotic creating what for water movement from the lumen, into the cells and interstitium.

Back 113

the osmotic gradient

Front 114

In the descending thin loop of Henle, What mainly happens?

Back 114

water reabsorption

increased concentration of Na and Cl( and any other solute) within the tubular fluid.

Front 115

Water is reabsorbed, but not Na+ in the descending thin loop of Henle, so there is an increase of what in the luminal fluid?

Back 115

increased concentration of Na+

Front 116

In the ascending thin loop of Henle, What is the permeability of Na and water?

Back 116

impermeable to water,
permeable to Na+

Front 117

Since Na+ concentration had increased in the descending loop, now the Na+ in the ascending loop of Henle can?

Back 117

move passively out of the tubule fluid into the interstitium

Front 118

What are the 2 transporters in TAHL?

Back 118

Apical transporter of NKCC (Na+, K+, 2Cl- cotransporter) w/ apical K+ channel

paracellular transport of Na+ w/ apical Na+/H+ exchange

Front 119

The K+ of NKCC is _________ and how?

Back 119

recycled

enters through the NKCC transporter, but exits back to the lumen through the apical K+ channel

Front 120

Why is recycling K+ in TAHL helpful?

Back 120

Helps run the symport

Front 121

In the TAHL, What is the normal concentration of K+ in ECF?

Back 121

???

Front 122

In TAHL, there is …….. of Na+, and an apical

Back 122

paracellular transport

Na+/H+ exchange

Front 123

What is the TAHL permeability of Na+ and water?

Back 123

impermeable to water,
permeable to Na+

Front 124

Loop of Henle as a whole has reabsorbed more solute than fluid, so the TALH is called?

Back 124

the diluting segment

Front 125

the TALH is called the diluting segment, and fluid leaving this segment, and entering the distal tubule, has what osmolarity?

Back 125

hypoosmotic

Front 126

The TAHL has ______ molarity then plasma

Back 126

lower

Front 127

What does the Macula Densa do?

Back 127

senses the outcome
(delivery rate of NaCl)

Front 128

If there is an increase of GFR when the rate of NaCl in fluid leaving the proximal tubule will?

Back 128

Increase

Front 129

If the rate of NaCl in fluid leaving the proximal tubule increases, then the delivery of NaCl to the macula densa will?

Back 129

Increase

Front 130

If the delivery of NaCl to the macula densa increases, then the …….. activates.

Back 130

Tubuloglomerular Reflex

Front 131

What happens if the Tubuloglomerular Reflex of the Macula Densa activates?

Back 131

Vasoconstriction of afferent arteriole which lowers the GFR

Front 132

Fluid entering Distal convoluted tubule (DCT)
Has what type of osmolarity?

Back 132

hypoosmotic

Front 133

Distal convoluted tubule (DCT) of does what with filtered NaCl

Back 133

Reabsorbs ~ 5%

Front 134

Distal convoluted tubule (DCT) uses what type of transport to reabsorb filtered NaCl

Back 134

1. Na+ / Cl – cotransporter (TSC1)

Front 135

What is the Distal convoluted tubule (DCT) permeability of Na+ and water?

Back 135

little H2O reabsorption

permeable to Na+

Front 136

What is the Collecting Duct (CD)
permeability of Na+ and water?

Back 136

permeable to Na+ & H2O

Front 137

Distal convoluted tubule (DCT) uses what type of transport to reabsorb filtered NaCl

Back 137

Na Channels (ENaC)
K+ Channels

Front 138

Medullary interstitium is hyperosmotic, so increasing permeability in CT and CD will allow water to enter interstitium, and will?

Back 138

increase the osmolality of the tubular fluid

Front 139

What does Aldosterone do for Na+ reabsorption in the CD?

Back 139

regulates by increasing the number of Na+ channels, and the Na/K ATPase.

Front 140

How would you increase the number of Na+ channels, and the Na/K ATPase in the CD?

Back 140

Add aldosterone

Front 141

Increasing aldosterone levels in the CD will increase what?

Back 141

Na+ reabsorption.

Front 142

What can blocks the aldosterone effect on Na+ channels in the CD?

Back 142

ANP

Front 143

What does aldosterone do for K+ reabsorption in the CD?

Back 143

increases K+ secretion

Front 144

Water reabsorption in the CD is impermeable, unless there is?

Back 144

Vasopressin (ADH, AVP).

Front 145

What does Vasopressin do for water channels?

Back 145

Vasopressin regulates the insertion of water channels.

Front 146

Water reabsorption only in the presence of?

Back 146

vasopressin (ADH)

Front 147

In the CD of a nephron, water permeability is regulated by?

Back 147

vasopressin.

Front 148

In the CD of a nephron, water permeability is regulated by vasopressin. How is this done?

Back 148

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).

Front 149

Water can always exit the CD of a nepthron at the ______ side, because that membrane is always permeable to water

Back 149

basolateral

Front 150

During water reabsorption in the CD, Vasopressin of a nephron binds to the ________ on the basolateral membrane

Back 150

V2 receptor.

Front 151

During water reabsorption in the CD, Vasopressin of a nephron binds to the V2 receptor on the basolateral membrane, what happens

Back 151

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.

Front 152

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?

Back 152

resulting in cAMP

increased transcription of genes for aquaporin-2,

and

increased formation and insertion of aquaporin-2 channels.

Front 153

Fluid entering and leaving the Distal convoluted tubule (DCT). Has what type of osmolarity?

Back 153

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

Front 154

Vasopressin controls about what % of the total water reabsorption

Back 154

20

Front 155

Cortical and medullary collecting tubules reabsorb about 5-7% of the filtered load of Na+, compensating for?

Back 155

daily fluctuations in diet and Na+ excretion.

Front 156

What are the Intercalated cells of the Collecting Ducts (CD)?

Back 156

1. H+ secretion, HCO3- reabsorption.
2. Potassium reabsorption.

Front 157

Among the two Intercalated cells of the Collecting Ducts (CD), Which is responsible for acid/base balance?

Back 157

H+ secretion, HCO3- reabsorption.

Front 158

What happens during the H+ secretion, HCO3- reabsorption (the Intercalated cells) of the Collecting Ducts (CD)?

Back 158

- 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

Front 159

What is formed during the H+ secretion, HCO3- reabsorption (the Intercalated cells) of the Collecting Ducts (CD)?

Back 159

Hydrogen and bicarbonate formed from water
and carbon dioxide in the cell (carbonic anhydrase).

Front 160

During the H+ secretion, HCO3- reabsorption (the Intercalated cells) of the Collecting Ducts (CD), what happens to bicarbonate?

Back 160

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

Front 161

During the H+ secretion, HCO3- reabsorption (the Intercalated cells) of the Collecting Ducts (CD), what happens to H+?

Back 161

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

Front 162

The H+ secretion, HCO3- reabsorption of the Collecting Ducts (CD) process is stimulated by?

Back 162

academia

Front 163

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?

Back 163

K+ATPase of the intercalated cells

Front 164

Hormonal regulation of Na+ & water reabsorption
in the Proximal tubule is regulated by?

Back 164

Angiotensin II

Front 165

How does Angiotensin II
affect the proximal tubule?

Back 165

Increased Na+ & water reab.

Fluid is Isoosmotic

Front 166

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

Back 166

aldosterone

ANP

Vasopressin

Front 167

How does aldosterone
affect the Collecting tubules?

Back 167

Increase Na+ reabsorption in collecting duct

Front 168

Hormonal regulation of Na+ & water reabsorption in the Collecting tubules is regulated by?

Back 168

ANP

Front 169

How does ANP affect the Collecting tubules?

Back 169

Inhibits the effects of aldosterone

Front 170

Hormonal regulation of Na+ & water reabsorption in the Collecting tubules is regulated by?

Back 170

Vasopressin

Front 171

How does Vasopressin affect the Collecting tubules?

Back 171

Increases water reabsorption in collecting duct

Front 172

What do Diuretics do?

Back 172

They interfere w/ Na+ reabsorption

Front 173

What would happen if you took a diuretic?

Back 173

Decrease in ECF volume and then a decrease in blood pressure

Front 174

Transporters are …………., subject to …………………, and the target of what?

Back 174

molecularly distinct

different disorders

different drugs - diuretics

Front 175

Diuretics have different side effects, depending on?

Back 175

the molecular target

Front 176

4 Renal mechanisms for excreting dilute or concentrated urine

Back 176

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

Front 177

Water follows solute in the proximal tubule, but water and solute are regulated how in other segments of the nephron?

Back 177

Separately

Front 178

The interstitium of the medulla (not the cortex) has a _____ gradient of solute

Back 178

Steep

Front 179

Urea recycles from ….. to…..then and adds to?

Back 179

medullary interstitium to tubular lumen and back to interstitium

the solute gradient of the interstitium

Front 180

The ____ ______ helps maintain the solute gradient of the medullary intersitium

Back 180

vasa recta

Front 181

In osmotic gradients in the medullary interstitium,
All renal corpuscles are in the ?

Back 181

cortex

Front 182

In osmotic gradients in the medullary interstitium,
Total loop of Henle is in …… for?

Back 182

medulla

juxta-medullary nephrons

Front 183

In osmotic gradients in the medullary interstitium,
What is in the medulla for juxta-medullary nephrons?

Back 183

Total loop of Henle

Front 184

In osmotic gradients in the medullary interstitium,
What is in the medulla for cortical nephrons?

Back 184

TALH

Front 185

The Interstitial fluid of the Cortex is what type of osmolarity?

Back 185

Isoosmotic

Front 186

The Interstitial fluid of the Medulla is what type of osmolarity?

Back 186

hyperosmotic,

following a gradient of 300mosm (at cortical-medullary Junction) to as much as 1400mosm at apex of medulla. (region closest to the calyx)

Front 187

Vasa recta blood comes from the ?

Back 187

the efferent arteriole

Front 188

Vasa recta blood pathway from efferent arteriole to veins in the Cortex:

Back 188

the efferent arteriole ~~> arcurate artery ~~> interlobar artery ~~> capillary of the vasa recta ~~> interlobar veins ~~> arcurate vein ~~> Renal Vein

Front 189

Vasa recta blood pathway does not just pass through the medulla, but follows:

Back 189

the loop of Henle, and returns back to the cortex

Front 190

What is Water Diuresis?

Back 190

Increased urine excretion resulting from low vasopressin or Absence of ADH/Vasopressin

Front 191

With water diuresis in the Proximal tubule, name 3 facts.

Back 191

Permeable to water and salt;
interstitium and tubular fluid is isoosmotic,

Front 192

With water diuresis in the Proximal tubule, What is permeable?

Back 192

Permeable to water and salt;

Front 193

With water diuresis in the Descending loop of Henle, What is permeable and how does it pass through?

Back 193

Permeable to water, and passing through a hyperosmotic interstitium, so water leaves the tubular lumen.

Less permeable to salt and urea.

Front 194

With water diuresis in the Descending loop of Henle, Tubular fluid becomes ________, and at bend ~= _________ .

Back 194

hyperosmotic
interstitium

Front 195

With water diuresis in the Descending loop of Henle, Solutes of tubule differ from interstitium. They are?

Back 195

NaCl lumen
Urea lumen

NaCl lumen (greater than) interstitium

Urea lumen (less than) interstitium

Front 196

With water diuresis in the Descending loop of Henle, Solutes of tubule differ from interstitium.

NaCl lumen _____ interstitium

Back 196

Greater than
>

Front 197

With water diuresis in the Descending loop of Henle, Solutes of tubule differ from interstitium. How?

Urea lumen ___ interstitium

Back 197

Less than
<

Front 198

Where in the nephron is H2O permeable?

Back 198

Proximal tubule - PT
Descending Loop of Henle - DLOH

Front 199

Where in the nephron are solutes most concentrated?

Back 199

at bend of the Descending Loop of Henle - DLOH

Front 200

Where in the nephron is urea facilitated diffused back into the nephron

Back 200

Ascending Loop of Henle - ALH

Medullary Collecting Duct - MCD

Front 201

Where in the nephron is NaCl permeable?

Back 201

Ascending Loop of Henle – ALH

Thick Ascending Loop of Henle - TALH

And to the first bend of the Distral Tube – DT

Front 202

Where in the nephron is more Na+ and H2O absorbed than usual?

Back 202

The first bend of the Distral Tube – DT

Front 203

Where in the nephron is the solutes more dilute than any other time?

Back 203

The first bend of the Distral Tube – DT

Front 204

Where in the nephron is water impermeable?

Back 204

Cortical Collecting Duct - CCD

Medullary Collecting Duct - MCD

Front 205

With water diuresis in the Ascending thin loop of Henle - ALH, name 3 facts.

Back 205

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

Front 206

With water diuresis in the Ascending thin loop of Henle - ALH, What is permeable?

Back 206

Impermeable to water. Permeable to salt and urea,

Front 207

With water diuresis in the Ascending thin loop of Henle - ALH, concentration gradients promote?

Back 207

NaCl exit from lumen, and urea entrance into lumen.

Front 208

With water diuresis in the Ascending thin loop of Henle - ALH, Net flux of NaCl (G/S/L) that of urea, so there is….?

Back 208

Greater than (>)

a net loss of solutes, and the fluid is diluted

Front 209

With water diuresis in the thick ascending loop of Henle (TALH), What is permeable?

Back 209

Impermeable to water and urea.

Front 210

With water diuresis in the thick ascending loop of Henle (TALH), there is active reabsorption of Na+, so fluid becomes?

Back 210

hypoosmotic

Front 211

With water diuresis in the thick ascending loop of Henle (TALH), name 2 facts.

Back 211

Impermeable to water and urea.

there is active reabsorption of Na+, so fluid becomes hypoosmotic

Front 212

With water diuresis in the Distral Tube – DT,
name 2 facts.

Back 212

Impermeable to water

fluid remains hypoosmotic

Front 213

With water diuresis in the Ascending thin loop of Henle - ALH, What is permeable?

Back 213

Impermeable to water

Front 214

With water diuresis in the Cortical collecting duct – CCT, name 3 facts.

Back 214

Active reabsorption of NaCl, but impermeable to urea.

Impermeable to water in the absence of ADH.

Fluid becomes more hypoosmotic

Front 215

With water diuresis in the Cortical collecting duct – CCT, What is permeable?

Back 215

Active reabsorption of NaCl, but impermeable to urea.

Impermeable to water in the absence of ADH.

Front 216

With water diuresis in the Cortical collecting duct – CCT, What is the Osmolarity?

Back 216

Fluid is more hypoosmotic

Front 217

With water diuresis in the Medullary collecting duct – MCD, name 3 facts.

Back 217

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

Front 218

With water diuresis in the Medullary collecting duct – MCD, What is permeable?

Back 218

Active reabsorption of NACl continues.

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

Front 219

With water diuresis in the Medullary collecting duct – MCD, What is the Osmolarity?

Back 219

Trying to keep Hypertonic

Front 220

The Processes of the TALH in step 4 allow which step to proceed?

Back 220

The Na+ from step 4 allows H2O to leave DLH in Step 2 (by Gradient)

Front 221

Urea is freely filtered, and reabsorbed in?

Back 221

the proximal tubule (~50% filtered load)

Front 222

Urea is secreted in the?

Back 222

thin loop of Henle, (~filtered load)

Front 223

Urea concentration = formula

Back 223

amount/volume

Front 224

The volume of fluid in the TLH has _________ from its travel from the proximal tubules

Back 224

decreased

Front 225

concentration of urea entering ATLH (G/S/L) concentration in proximal tubule

Back 225

Greater than (>)

Front 226

What happens to the Urea in the Collecting duct?

Back 226

urea is reabsorbed, and contributes to the hyperosmolality of the medulla

Front 227

What contributes to the hyperosmolality of the medulla?

Back 227

Urea in the Collecting duct

Front 228

Medullary gradient is % NaCl and ___ % urea.

Back 228

50% NaCl and 50% urea.

Front 229

Diabetes insipidus – insipidus means?

Back 229

Tasteless

Front 230

What is Diabetes insipidus?

Back 230

posterior pituitary defect

Front 231

Diabetes insipidus results in ?

Back 231

deficient vasopressin release.

Front 232

What would be the outcome of someone with Diabetes insipidus?

Back 232

Dilute urine

Up to 18 L a day

Front 233

Where in the nephron is aquaporins available due to Vasopressin?

Back 233

Cortical Collecting Duct - CCD
Medullary Collecting Duct - MCD

Front 234

Summerize the first 5 Steps for diuresis?

Back 234

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.

Front 235

What is the sixth step for diuresis?

Back 235

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.

Front 236

What is the osmolarity (#) of cortical interstitium?

Back 236

this interstitium has an osmolality of 300mOsm/L

Front 237

What is the seventh step for diuresis?

Back 237

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.

Front 238

Urine osmolality ranges from?

Back 238

50mOsm/L (water diuresis) to 1200 mOsm/L (antidiuresis).

Front 239

Urine volume ranges from?

Back 239

the obligate loss of 500mL/day to about 18L

Front 240

Why is the finding of isoosmotic urine in a patient a cause for alarm?

Back 240

Suggest the kidneys aren’t working

Maybe there is a block at TALH

Front 241

The vasa recta is crucial for maintaining?

Back 241

the gradient

Front 242

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 …..

Back 242

concentration gradient

osmotic gradient

Front 243

What would happen if the vasa recta were straight,
flowing through the medulla, instead of returning to the cortex?

Back 243

“Straight vasa recta”:

Blood leaving the medulla would be hyperosmotic, and the osmotic gradient of the interstitium would be reduced causing “washed out”

Front 244

What would happen if the vasa recta lacked the hairpin turn?

Back 244

Hyperosmotic and loss of solute in interstitial fluid
causing “washed out

Front 245

What are the steps of blood osmolarity of the Vasa recta with hairpin turn?

Back 245

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.

Front 246

What are the steps of blood osmolarity of the Cortical Nephron with the Vasa Recta?

Back 246

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.

Front 247

An individual wishes to prepare ahead of time for a
marathon by overhydrating several days before the
race. Why is this a bad idea?

Back 247

You would have a period of water loading

Diuretic ~~> reduced gradient

Front 248

Water and salt load can vary?

Back 248

independently

Front 249

Variations in Na+ affect?

Back 249

ECF volume

Front 250

Variations in water affect?

Back 250

osmolality

Front 251

What affects ECF volume?

Back 251

Variations in Na+

Front 252

What affects osmolality?

Back 252

Variations in water

Front 253

What are the effects of Isoosmotic dehydration (blood loss)?

Back 253

Decrease in ECF volume
No change is Osmolarity

Front 254

What are the effects of Isoosmotic Overhydration (taking in isotonic saline)?

Back 254

Increase in ECF volume
No change is Osmolarity

Front 255

What are the effects of Hyperosmotic dehydration (sweat loss)?

Back 255

Increase in Osmolarity
Decrease in ECF volume*

*Happens regardless w/ sweat loss

Front 256

What are the effects of Hypoosmotic dehydration (sweat loss with water replaced)?

Back 256

Decrease in Osmolarity
Decrease in ECF volume*

*Happens regardless w/ sweat loss

Front 257

What are the effects of hyperosmotic overhydration (taking in hypertonic fluid)?

Back 257

Increase in ECF volume
Increase in Osmolarity

Front 258

What are the effects of hypoosmotic overhydration (taking in pure water)?

Back 258

Increase in ECF volume
Increase in Osmolarity

Front 259

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?

Back 259

Isoosmotic dehydration
(blood loss)

Front 260

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?

Back 260

Isoosmotic Overhydration
(taking in isotonic saline)

Front 261

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?

Back 261

Hyperosmotic dehydration (sweat loss)

Front 262

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?

Back 262

Hypoosmotic dehydration
(sweat loss with water replaced)

Front 263

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?

Back 263

hyperosmotic overhydration
(taking in hypertonic fluid)

Front 264

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?

Back 264

hypoosmotic overhydration
(taking in pure water)

Front 265

What is the sensor specifically for total body Na+ homeostasis?

Back 265

There is no sensor specifically for total body Na+.

Front 266

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?

Back 266

ECF

Front 267

ECF = formula

Back 267

plasma volume + interstitial volume

Front 268

“blood volume is an important determinant of arterial pressure because it directly affects?

Back 268

venous pressure,
venous return,
end-diastolic volume,
stroke volume,
and cardiac output”

Front 269

What many sensors for ECF volume?

Back 269

Multiple sensors for ECF volume

Front 270

What are two types of sensors for ECF volume?

Back 270

Systemic
&
Renal

Front 271

What is the systemic sensor for ECF volume?

Back 271

baroreceptors,
in high pressure (i.e. carotid sinus)
and low pressure (atrial) sites

Front 272

Where are baroreceptors located?

Back 272

baroreceptors, in high pressure (i.e. carotid sinus) and low pressure (atrial) sites

Front 273

What are the Renal sensors for ECF volume?

Back 273

JG cells (stretch sensitive),
Macula Densa cells (flow sensitive)

Front 274

the JG cells of the Renal sensors for ECF volume
are ________ sensitive

Back 274

stretch

Front 275

the macula densa cells of the Renal sensors for ECF volume are_________ sensitive

Back 275

flow

Front 276

If the the JG cells of the Renal sensors for ECF volume increases its stretch, what happens?

Back 276

Decrease in Renin

Front 277

If the macula densa cells of the Renal sensors for ECF volume receive increased GFR, what happens?

Back 277

Increased rate of NaCl delivered

Front 278

What are the 5 effectors hormones of ECF volume:

Back 278

• Renin –
• Aldosterone
• Angiotensin II
• Vasopressin (ADH) Increases water reabsorption in
• ANP

Front 279

What are the facts of the effectors hormone Renin of ECF volume:

Back 279

released by JG cells, results in an increase in angiotensin II

Front 280

The effector hormone Renin is released by released by?

Back 280

JG cells

Front 281

The effector hormone Renin results in an increase in?

Back 281

angiotensin II

Front 282

What are the facts of the effectors hormone Aldosterone of ECF volume:

Back 282

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

Front 283

The effector hormone Aldosterone increases?

Back 283

the Na+ reabsorption in the collecting ducts.

Front 284

The effector hormone Aldosterone regulates?

Back 284

2% of filtered load

Front 285

The effector hormone Aldosterone is secreted by?

Back 285

the adrenal gland

Front 286

Aldosterone is secreted by the adrenal gland in response to?

Back 286

angiotensin 2

Front 287

What are the facts of the effectors hormone Angiotensin II of ECF volume:

Back 287

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

Front 288

The effector hormone Angiotensin II affects what?

Back 288

aldosterone release

Front 289

The effector hormone Angiotensin II increases?

Back 289

Na+ reabsorption in proximal tubules

Front 290

Normal levels of the effector hormone Angiotensin II acts upon what type of arterioles?

Back 290

Acts on efferent arterioles

Front 291

High levels of the effector hormone Angiotensin II acts on what type of arterioles?

Back 291

afferent and efferent arterioles

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

Front 292

The effector hormone Angiotensin II increases?

Back 292

vasopressin release

Front 293

High levels the effector hormone, Angiotensin II will do what to vasopressin?

Back 293

Increase vasopressin release

Front 294

What are the facts of the effectors hormone Vasopressin (ADH) of ECF volume:

Back 294

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

Front 295

The effector hormone Vasopressin (ADH) increases?

Back 295

water reabsorption in the collecting ducts

Front 296

The effector hormone Vasopressin (ADH) regulates % of the filtered load?

Back 296

about 20%

Front 297

The effector hormone Vasopressin (ADH) is secreted by?

Back 297

posterior pituitary

Front 298

The effector hormone Vasopressin (ADH) is secreted by posterior pituitary in response to what two receptors?

Back 298

angiotensin 2 & other baroreceptor
mediated reflexes
and hypothalamic osmoreceptors

Front 299

What are the facts of the effector hormone ANP of ECF volume:

Back 299

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

Front 300

The effector hormone ANP is secreted by?

Back 300

the heart in response to atrial stretch

Front 301

The effector hormone ANP is secreted by the heart in response to?

Back 301

atrial stretch

Front 302

The effector hormone ANP inhibits what three things?

Back 302

Inhibits aldosterone action in the kidney;

inhibits aldosterone release,
and inhibits renin secretion

Front 303

The effector hormone ANP inhibits the release of?

Back 303

vasopressin release

Front 304

Vasopressin is usually controlled by?

Back 304

Osmolarity

Front 305

GFR is often constant due to?

Back 305

autoregulation
Ex. Tubloglomerular Feedback from (MD)

Front 306

Amount excreted = Formula

Back 306

amt filtered – amt reabsorbed = Amount excreted

Front 307

Amount filtered= P[x] * GFR
Another name for amount filtered is?

Back 307

Filtered load

Front 308

Decreases in GFR will decrease:

Back 308

the filtered load, and the excretion of Na+

Front 309

Reabsorption is a multi step process: explain the 3 steps.

Back 309

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

Front 310

The movement into the capillaries during reabsorption is regulated by Starling’s law, so that?

Back 310

an increased hydrostatic pressure in the capillaries will reduce reabsorption.

Front 311

An increase in arterial pressure during reabsorption, does what to reabsorption?

Back 311

the decreases Na+ reabsorption in the capillaries

Front 312

Increased Sympathetic outflow in Baroreceptor reflexes will affect?

Back 312

Arteriolar smooth muscle contraction (especially an afferent arteriolar)

GFR
Pressure naturesis

Front 313

High pressure by itself will ______ Na+ excretion

Back 313

increase

Front 314

Low pressure by itself will ______ Na+ excretion

Back 314

decrease

Front 315

(I/D) of arteriol pressure ~>
(I/D) hydrostatic pressure ~> ??

Back 315

Increase of arteriol pressure ~> Increase hydrostatic pressure ~> Na+ reabsorption

Front 316

Increased Sympathetic outflow in Baroreceptor reflexes will directly innervate JG cells, by doing this what chain rxn starts?

Back 316

sympathetic increase ~> increased renin
~> Angiotensin II ~> ANP ~ Vasopressin release

Front 317

ANP is released from?

Back 317

the heart

Front 318

Increased Sympathetic outflow in Baroreceptor reflexes will have what effect?

Back 318

Vasopressin release

Front 319

What is the behavior of Sympathetic outflow in Baroreceptor?

Back 319

thirst

Front 320

What are the two influences of water homeostasis?

Back 320

Osmolarity & extracellular fluid volume

Front 321

What is the primary and secondary influence of water homeostasis?

Back 321

Osmolarity & extracellular fluid volume

Front 322

What is the equation for Osmolarity & extracellular fluid volume and Osmolarity & intercellular fluid volume?

Back 322

Osmo / ECF = Osmo / ICF

Front 323

Sensors, and mechanisms result in changes in _____ which regulates distal
nephron water reabsorption.

Back 323

vasopressin (ADH),

Front 324

Sensors, and mechanisms result in changes in vasopressin (ADH), which regulates?

Back 324

Distal nephron water reabsorption.

Front 325

Many variations in ECF involve loss or gain in?

Back 325

both sodium and water.

Front 326

How many sensors are involved in water homeostasis?

Back 326

additional sensors (more than one)

Front 327

Osmoreceptors shrink or swell and that affects?

Back 327

mechanic sensitive ion channels

Front 328

Osmoreceptors Sensors is located in the?

Back 328

hypothalamus.

Front 329

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)

Back 329

2/3 to ICF
1/3 to ECF
Most H2O goes to ICF
(based on typical relative volumes of ECF and ICF)

Front 330

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

This will cause a slight change in?

Back 330

systemic blood pressure

Front 331

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

Back 331

large change

Front 332

Osmoreceptor reflex is located in?

Back 332

The Hypothalamus

Front 333

What triggers sense of thirst?

Back 333

The two Osmosreceptors of the Hypothalamus

Front 334

The Hypothalamus has how many sets of osmosreceptors?

Back 334

2

Front 335

What do osmosreceptors do?

Back 335

• 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

Front 336

How do the two Osmosreceptors of the Hypothalamus regulate release of vasopressin (ADH)?

Back 336

Decreased osmolarity which causes a decrease in vasopressin (ADH)

Front 337

What other factors that can increase or decrease vasopressin release

Back 337

Hemodynamic factors and other factors

Front 338

What Hemodynamic factors that can increase or decrease vasopressin release?

Back 338

ECF volume expansion

ECF volume reduction

Front 339

What does ECF volume expansion
of the Hemodynamic factors that can increase or decrease vasopressin release do?

Back 339

Large changes – 10% change of ECF which decreases ADH

Front 340

What does ECF volume expansion
of the Hemodynamic factors that can effect vasopressin release do?

Back 340

Decrease ADH

Front 341

What does ECF volume reduction of the Hemodynamic factors that can effect vasopressin release do?

Back 341

Increase ADH

Front 342

What are the others factors that can affect vasopressin release?

Back 342

Nausea, anxiety/fear, nicotine, angiotensin II


ANP, Ethanol

Front 343

What are the others factors that can increase vasopressin release?

Back 343

Nausea, anxiety/fear, nicotine, angiotensin II

Front 344

What are the others factors that can decrease vasopressin release?

Back 344

ANP, Ethanol

Front 345

What is the other effect that the others factors, ANP & Ethanol, that decrease vasopressin release?

Back 345

Dehydration

Front 346

What happens if you suffer from hypoosmotic overhydration (drinking pure water)?

Back 346

Decreased reabsorption of water (esp. in CT)

Increased water excretion

Front 347

What happens over time if you suffer from hypoosmotic overhydration (drinking pure water)?

Back 347

Wash out or decrease gradient in medulla = diuresis

Front 348

What happens if you suffer from hyperosmotic dehydration (Sweat with water replacement)?

Back 348

Osmolarity increase

ECF volume decreased

Front 349

if you suffer from hyperosmotic dehydration (Sweat with water replacement), how does Osmolarity increase?

Back 349

Increase of Vasopressin ~> Increase of Thirst ~> Increase of Water reabsorption (decrease in Excretion)

Front 350

if you suffer from hyperosmotic dehydration (Sweat with water replacement), how does ECF volume decrease?

Back 350

Increase of Renin-angiotensin II-aldosterone
~> decrease Pressure natriuresis ~ > GFR (may or may not change) ~> increase in Na+ reabsorption

Front 351

For large changes in ECF volume, restoring _____ has has priority over restoring ____ hypoosmotic dehydration during hypoosmotic dehydration

Back 351

ECF volume
Osmolarity

Front 352

For large changes in ECF volume, Why does restoring ECF volume have priority over restoring Osmolarity during hypoosmotic dehydration?

Back 352

ECF volume will override osmolarity, and vasopressin will be released

Front 353

Sweat lose w/ H2O replacement steps for decrease in osmolarity and ECF volume?

Back 353

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

Front 354

Large disturbances of ECF volume incorporate ……. Regulation and example?

Back 354

both Na+ and water

Example: Hemorrhage

Front 355

What happens with ECF volume during a hemorrhage?

Back 355

Loss of isotonic fluid volume from the extracellular compartment

Increased reabsorption of water and salt

Front 356

If you decrease ANP, what happens?

Back 356

Less inhibition of aldosterone

Less inhibition of Osmoreceptor