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Histo (VM1 Fall) > Exam 3 - Lecture 39 (Control of Fluid Volume and Osmolality) > Flashcards

Exam 3 - Lecture 39 (Control of Fluid Volume and Osmolality) Flashcards

1
Q

What is the most abundant EC ion/substance?

A

Na+

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2
Q

What is the most abundant IN ion/substance?

A

K+

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3
Q

How does changing ECF [Na+] change ECF osmolarity?

A

Increase EC [Na+] = Increase osmolarity

Decrease EC [Na+] = Decrease osmolarity

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4
Q

How does changing ECF Na+ amount change ECF volume?

A

Increase EC Na+ amount = increased ECF volume

Decrease EC Na+ amount = decreased ECF volume

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5
Q

How does the kidney regulate ECF osmolarity?

A

By changing ECF Na+ CONCENTRATION

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6
Q

How does the kidney regulate ECF volume?

A

By changing ECF Na+ AMOUNT

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7
Q

What happens to ICF if ECF osmolarity is too high?

A

fluid moves out of IC space

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8
Q

What happens to ICF if ECF osmolarity is too low?

A

fluid moves into IC space

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9
Q

What is hypernatremia?

A

High ECF [Na+]

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10
Q

What 4 things can hypernatremia cause?

A
  1. Rupture of cerebral vessels/hemorrhage
  2. Muscle weakness
  3. Behavioral changes/ataxia
  4. Coma leading to death
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11
Q

What is hyponatremia?

A

Low ECF [Na+]

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12
Q

What 3 things can hyponatremia cause?

A
  1. Cerebral/pulmonary edema
  2. Muscle weakness
  3. Incoordination and seizures
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13
Q

Why would hemorrhage occur during hypernatremia?

A

Bc of pressure buildup

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14
Q

Why would muscle weakness occur during hypernatremia?

A

Bc ells cannot contract efficiently

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15
Q

Why would cerebral/pulmonary edema occur during hyponatremia?

A

Bc of fluid buildup

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16
Q

Why would muscle weakness occur during hyponatremia?

A

Bc cells cannot contract efficiently

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17
Q

Control of ECF osmolarity = control of ECF Na+ _____.

A

concentration

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18
Q

What is concentration?

A

Amount of a specified substance (Na+) in a unit amount of another substance (water).

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19
Q

ADH is released when ECF osmolarity is _____.

A

high

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20
Q

What receptor triggers the thirst mechanism?

A

osmoreceptors

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21
Q

When is the thirst mechanism triggered/suppressed?

A

Triggered when ECF fluid osmolarity is high (ADH released)

Suppressed when ECF osmolarity is low (ADH not released)

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22
Q

Which statement about hyponatremia is most accurate?

A) A hyponatremic animal will have high ECF Na+ concentration
B) There will likely be translocation of fluid from ECF to ICF
C) Osmoreceptors in hypothalamus will shrink
D) ADH release will be increased
E) The animal will feel thirsty

A

B) There will likely be translocation of fluid from ECF to ICF

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23
Q

ECF volume is changed by ECF Na+ _____.

A

amount

24
Q

What is hypervolemia?

A

High ECF volume

25
Q

What 2 things can hypervolemia cause?

A
  1. Ascites (abdominal swelling)

2. Pulmonary edema

26
Q

What 2 things can hypovolemia cause?

A
  1. Hypovolemic shock

2. Organ damage

27
Q

What is hypovolemia?

A

Low ECF volume

28
Q

Between hypervolemia and hypovolemia, which is worse?

A

Hypovolemia

29
Q

What 2 things detect changes in ECF volume?

A
  1. Baroreceptors

2. JGA

30
Q

How do baroreceptors respond to low ECF volume?

A

Increase sympathetic flow to the kidneys

31
Q

How do baroreceptors respond to high ECF volume?

A

Decrease flow by stimulating natriuretic peptide release

32
Q

Baroreceptors that sense changes in volume are located in the _____ and _____. Why?

A

left atria and pulmonary vessels; they are on venous side where most of the volume is

33
Q

Baroreceptors that sense changes in pressure are located in the _____ and _____. Why?

A

Aortic arch and sinus; sends signal to brainstem to knock down sympathetic flow

34
Q

Which type of baroreceptor (volume or pressure) is more important?

A

High pressure baroreceptors

35
Q

How do JG cells act as stretch receptors in the afferent arterioles?

A

Increase flow by triggering Renin secretion in response to stretch

36
Q

How do baroreceptors and the JGA regulate GFR and reabs. to control Na+ retention (2 ways)?

A
  1. Increase Na+ retention when ECF volume too low

2. Decrease Na+ retention when ECF volume is high

37
Q

Baroreceptors detect decreased ECF volume to _____ sympathetic flow.

A

increase

38
Q

Norepinephrine is a vaso_____.

A

constrictor

39
Q

What effect does norepinephrine have on the arterioles of the glomerulus, GFR, and Na+ reabs.?

A

Efferent constricts more than afferent = increased GFR = increased Na+ reabs.

40
Q

What 3 things does norepinephrine do?

A
  1. Vasoconstriction
  2. Stimulates Na+ reabsorption from PT
  3. Stimulates renin release from JGA to activate Renin-Angiotensin System
41
Q

How does decreased ECF volume induce renin release and angiotensin II?

A

Induces renin release and increases angiotensin II

42
Q

What arterioles does ANG II constrict and why?

A

efferent to increase GFR

43
Q

Why does ANG II change Starling’s Forces?

A

To increase Na+ and water uptake

44
Q

What does ANG II stimulate to increase Na+ uptake?

A

Na+-H+ antiporter and aldosterone

45
Q

What does ANG II stimulate to increase water uptake?

A

ADH release

46
Q

What 3 things does aldosterone do once stimulated by ANG II?

A
  1. Stimulates # and activity of Na+K+ATPase
  2. Stimulates NKCC1 in DST
  3. Stimulates Na+ channels in CD
47
Q

What are natriuretic peptides?

A

Peptides that increase Na+ in urine (decrease reabsorption of urine)

48
Q

Where is Atrial Natriuretic Peptide (ANP) synthesized?

A

atrial myocytes

49
Q

Where is Brain Natriuretic Peptide (BNP) synthesized?

A

cardiac ventricles

50
Q

When are natriuretic peptides (ANP and BNP) released?

A

In response to stretch/increased ECF volume

51
Q

What 5 things do natriuretic peptides do?

A
  1. Constrict efferent art./dilate afferent art. = increase GFR = {increase Na+ and water load entering tubules}
  2. {Inhibit renin release} from JGA = inhibit RAS
  3. {Inhibit ADH release} by inhibiting RAS
  4. {Inhibit aldosterone} release by inhibiting RAS (act directly on adrenal cortex)
  5. {Inhibit NaCl reabs.} in CD by inhibiting Na+ channels
52
Q

Increased natriuretic peptide _____ Na+ reabsorption which _____ water reabsorption and _____ ECF volume.

A

decreases; reduces; decreases

53
Q

Which statement about hypovolemia is accurate?

A) It is defined as high ECF volume
B) It is caused by low ECF [Na+]
C) The animal will respond by increasing sympathetic flow to the kidneys
D) To correct it, the RAS will be inhibited
E) The animal will respond by increased release of natriuretic peptides

A

C) The animal will respond by increasing sympathetic flow to the kidneys

54
Q

What system will try to correct hypervolemia?

A

natriuretic peptides

55
Q

Low ECF volume is returned to normal by:

A) Stimulation of RAS
B) Increased ADH secretion
C) Increased sympathetic flow
D) A and C only
E) A, B and C
A

A) Stimulation of RAS
B) Increased ADH secretion
C) Increased sympathetic flow

Histo (VM1 Fall) (27 decks)

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