Regulation of Sodium and Water Balance

Question 1

What are the low pressure CP circuit components

Answer 1

Cardiac atria and pulmonary vasculature

Question 2

What are the high pressure arterial circuit components

Answer 2

Carotid sinus, aortic arch, JG apparatus

Question 3

Total body sodium equals what

Answer 3

Dietary Na - urinary excretion

Question 4

When ECF is low, what is Na excretion and retention?

Answer 4

Decreased; increased

Question 5

When ECF volume is high, what is Na retention and excretion?

Answer 5

Decreased; increased

Question 6

What factors serve to increase Na excretion

Answer 6

• dopamine
• ECF [Na] increase
• ECF volume increase
• Natriuretic peptides

Question 7

What factors contribute to decrease Na excretion

Answer 7

• RAAS
• sympathetics
• ADH

Question 8

What are the main functions of RAAS

Answer 8

Retain water
Retain Na
Kick K

Question 9

What activates renal sympathetics

Answer 9

• constriction of afferent arterioles (decrease in GFR)
• increased tubular reabsorption of water and salt
• activated RAAS

Question 10

What promotes renin secretion

Answer 10

• symp stim of JG by β1
• decreased NaCl delivery to macula densa
• afferent arteriole vasoconstriction

Question 11

What inhibits renin secretion

Answer 11

• increased Na Cl reabsorption at macula densa
• increased afferent arteriole pressure
• ADH
• Ang II (negative feed back)

Question 12

What does ang II stimulate

Answer 12

• efferent constriction more than afferent
• Na reabsorption in the PT (via NaH exchanger)
• increased thirst
• increased ADH secretion from post pit
• increased aldosterone secretion from adrenal cortex

Question 13

What does Ang II do for reabsorption of Na in the LoH

Answer 13

Increases it

Question 14

What does aldosterone cause at the DT

Answer 14

Increased Na reabsorption and increased K secretion

Question 15

What intracellular receptor does aldosterone bind to

Answer 15

MR (mineralocorticoid receptor)

Question 16

What transporter is produced in greater numbers in response to aldosterone

Answer 16

NaK ATPase and ENaC

Question 17

How does aldosterone have the overall result of an increase in Na reabsorption and increase in K excretion

Answer 17

Increased synthesis and activity of NaK ATPase

Increased synthesis and activity of ENaC in apical membrane

Question 18

What cells in the late DT and CD are responsible for increased Na and H2O reasborption and K secretion

Answer 18

Principal cells

Question 19

What are the 3 ions affected by aldosterone

Answer 19

Na (increased reabsorption)

K and H (increased secretion)

Question 20

Where are the most sensitive osmolality receptors

Answer 20

Hypothalamus and liver

Question 21

What is ADH secretion more sensitive to

Answer 21

Increases in osmolality

Question 22

What two things does ADH secretion rely on

Answer 22

Hyperosmolality and volume depletion

Question 23

Where are the baroreceptors

Answer 23

Aorta and carotid sinus

Question 24

What 3 main actions does ADH do

Answer 24

1. Increases water permeability of principal cells by inserting more aquaporins
2. Increases urea permeability in the inner medullary collecting ducts
3. Increased the activity of the NKCC in the TAL

Question 25

What does ADH bind to extracellularly

Answer 25

V2 receptor and functions through Gαs

Question 26

What happens after ADH binds to its receptor

Answer 26

AQP2 (aquaporin) is inserted into the apical membrane

Question 27

What happens when ADH levels decrease

Answer 27

AQP2 is endocytosed and recycled

Question 28

Which AQP are unaffected by ADH levels? Where are they

Answer 28

3 and 4; they are on the basolateral membrane

Question 29

Where are the osmoreceptors in the hypothalamus

Answer 29

OVLT and SFO

Question 30

What is special about the OVLT and SFO

Answer 30

They are outside the BBB

Question 31

What carries the signal from the brain osmoreceptors to the hypothalamus

Answer 31

Magnocellular neurons

Question 32

Where is ADH released into circulation

Answer 32

Posterior pituitary

Question 33

What things stimulate ADH secretion

Answer 33

Nausea, ang II, nicotine

Question 34

What inhibits ADH secretion

Answer 34

ANP and EtOH

Question 35

What are prostaglandins protective of

Answer 35

RBF

Question 36

What buffers the vasoconstrictive effects of SNS/RAAS

Answer 36

Prostaglandins

Question 37

What do NSAIDs lead to a retention of

Answer 37

Na because PGE2 is interfered with

Question 38

What pts would we want to be careful when administering NSAIDs

Answer 38

HTN, renal stenosis, pts on diuretics

Question 39

What increases ADH

Answer 39

- increased plasma osmolality - decreased BP - decreased BV - nicotine

Question 40

What decreases ADH

Answer 40

- decreased plasma osmolality - increased BP - increased BV - EtOH

Question 41

What increases thirst

Answer 41

- increased plasma osmolality - decreased BP - decreased BV - increased Ang II - mouth dryness

Question 42

What decreases thirst

Answer 42

- decreased plasma osmolality - increased BP - increaesd BV - decreased Ang II - gastric distension

Question 43

Where do ANP/BNP come from? What are they secreted in response to?

Answer 43

Atria and ventricles; increased stretch of cardiomyocytes

Question 44

What does ANP/BNP do for Na and water

Answer 44

Promotes NaCl and water excretion

Question 45

What change does ANP/BNP cause in GFR

Answer 45

Elevated

Question 46

What action does ANP/BNP have on vessels

Answer 46

Systemic vasodilator

Question 47

Where is urodilatin produced and what does it do

Answer 47

Kidney Promotes NaCl secretion and have no effect on systemic vasoactivity

Question 48

What do naturietic peptides generally oppose

Answer 48

RAAS, sympathetic NS, and ADH

Question 49

What actions do natriuretic peptides cause on the kidneys

Answer 49

increased GFR, decreased renin, decreased aldosterone, decreased Na and H2O reabs in CD, decresed ADH

Question 50

What stimulates secretion of ADH

Answer 50

- increased plasma osmolality - decreased BV - decreased BP

Question 51

What stimulates secretion of PTH

Answer 51

- decreased plasma [Ca] - increased plasma [PO4] - decreased plasma [calcitriol]

Question 52

What stimulates aldosterone secretion

Answer 52

- decreased BP - decreased BV - increased plasma [K]

Question 53

What 4 responses does increased Na intake cause

Answer 53

- decreased sympathetic activity - increased ANP - decreased πc - decreased RAAS

Question 54

What does decreased Na intake cause

Answer 54

- increased sympathetic activity - decreased ANP - increased πc - increased RAAS

Question 55

What is the hemorrhage response

Answer 55

- RAAS activation - sympathetic activation - ADH release - decreased Pa and baroreceptor response - altered blood gases (chemoreceptor reflex)

Question 56

Where is the JG apparatus

Answer 56

Distal convoluted tubule