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

Question 1

What is the most abundant EC ion/substance?

Answer 1

Na+

Question 2

What is the most abundant IN ion/substance?

Answer 2

K+

Question 3

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

Answer 3

Increase EC [Na+] = Increase osmolarity

Decrease EC [Na+] = Decrease osmolarity

Question 4

How does changing ECF Na+ amount change ECF volume?

Answer 4

Increase EC Na+ amount = increased ECF volume

Decrease EC Na+ amount = decreased ECF volume

Question 5

How does the kidney regulate ECF osmolarity?

Answer 5

By changing ECF Na+ CONCENTRATION

Question 6

How does the kidney regulate ECF volume?

Answer 6

By changing ECF Na+ AMOUNT

Question 7

What happens to ICF if ECF osmolarity is too high?

Answer 7

fluid moves out of IC space

Question 8

What happens to ICF if ECF osmolarity is too low?

Answer 8

fluid moves into IC space

Question 9

What is hypernatremia?

Answer 9

High ECF [Na+]

Question 10

What 4 things can hypernatremia cause?

Answer 10

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

Question 11

What is hyponatremia?

Answer 11

Low ECF [Na+]

Question 12

What 3 things can hyponatremia cause?

Answer 12

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

Question 13

Why would hemorrhage occur during hypernatremia?

Answer 13

Bc of pressure buildup

Question 14

Why would muscle weakness occur during hypernatremia?

Answer 14

Bc ells cannot contract efficiently

Question 15

Why would cerebral/pulmonary edema occur during hyponatremia?

Answer 15

Bc of fluid buildup

Question 16

Why would muscle weakness occur during hyponatremia?

Answer 16

Bc cells cannot contract efficiently

Question 17

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

Answer 17

concentration

Question 18

What is concentration?

Answer 18

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

Question 19

ADH is released when ECF osmolarity is _____.

Answer 19

high

Question 20

What receptor triggers the thirst mechanism?

Answer 20

osmoreceptors

Question 21

When is the thirst mechanism triggered/suppressed?

Answer 21

Triggered when ECF fluid osmolarity is high (ADH released)

Suppressed when ECF osmolarity is low (ADH not released)

Question 22

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

Answer 22

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

Question 23

ECF volume is changed by ECF Na+ _____.

Answer 23

amount

Question 24

What is hypervolemia?

Answer 24

High ECF volume

Question 25

What 2 things can hypervolemia cause?

Answer 25

1. Ascites (abdominal swelling) | 2. Pulmonary edema

Question 26

What 2 things can hypovolemia cause?

Answer 26

1. Hypovolemic shock | 2. Organ damage

Question 27

What is hypovolemia?

Answer 27

Low ECF volume

Question 28

Between hypervolemia and hypovolemia, which is worse?

Answer 28

Hypovolemia

Question 29

What 2 things detect changes in ECF volume?

Answer 29

1. Baroreceptors | 2. JGA

Question 30

How do baroreceptors respond to low ECF volume?

Answer 30

Increase sympathetic flow to the kidneys

Question 31

How do baroreceptors respond to high ECF volume?

Answer 31

Decrease flow by stimulating natriuretic peptide release

Question 32

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

Answer 32

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

Question 33

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

Answer 33

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

Question 34

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

Answer 34

High pressure baroreceptors

Question 35

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

Answer 35

Increase flow by triggering Renin secretion in response to stretch

Question 36

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

Answer 36

1. Increase Na+ retention when ECF volume too low | 2. Decrease Na+ retention when ECF volume is high

Question 37

Baroreceptors detect decreased ECF volume to _____ sympathetic flow.

Answer 37

increase

Question 38

Norepinephrine is a vaso_____.

Answer 38

constrictor

Question 39

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

Answer 39

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

Question 40

What 3 things does norepinephrine do?

Answer 40

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

Question 41

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

Answer 41

Induces renin release and increases angiotensin II

Question 42

What arterioles does ANG II constrict and why?

Answer 42

efferent to increase GFR

Question 43

Why does ANG II change Starling's Forces?

Answer 43

To increase Na+ and water uptake

Question 44

What does ANG II stimulate to increase Na+ uptake?

Answer 44

Na+-H+ antiporter and aldosterone

Question 45

What does ANG II stimulate to increase water uptake?

Answer 45

ADH release

Question 46

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

Answer 46

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

Question 47

What are natriuretic peptides?

Answer 47

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

Question 48

Where is Atrial Natriuretic Peptide (ANP) synthesized?

Answer 48

atrial myocytes

Question 49

Where is Brain Natriuretic Peptide (BNP) synthesized?

Answer 49

cardiac ventricles

Question 50

When are natriuretic peptides (ANP and BNP) released?

Answer 50

In response to stretch/increased ECF volume

Question 51

What 5 things do natriuretic peptides do?

Answer 51

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

Question 52

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

Answer 52

decreases; reduces; decreases

Question 53

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

Answer 53

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

Question 54

What system will try to correct hypervolemia?

Answer 54

natriuretic peptides

Question 55

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 ```

Answer 55

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