Regulation of Sodium Balance and Extracellular Fluid - Rao Flashcards Preview

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Flashcards in Regulation of Sodium Balance and Extracellular Fluid - Rao Deck (20):
1

What is ECFV proportional to?

Total body Na content

2

What are the ways that Na is excreted from the body?

Renal (80-90%)
Skin (0-20%) - sweat (half isotonic)
GI - (.5-10%) - diarrhea, vomiting (isotonic)

3

What are common causes of Na imbalance?

Diarrhea
Excessive sweating
Diuretics

4

What are the locations and amounts of renal Na reabsorption?

PT - 64% (isotonic)
LoH - 28%
DT / CD - 7%

5

What are signs of a decrease in ECFV?

Hypotension / Orthostatic hypotension

6

What are signs of an increase in ECFV?

Edema
Pulmonary edema (more severe)
Heart sounds (S3)
Jugular vein distension (JVD)

7

What can cause edema with normal or low ECFV?

Hypo-albuminemia

8

How quickly does the body react to changes in plasma osmolarity?

1-2 hours

9

How quickly does the body react to changes in Na intake?

2-4 days

10

What receptors regulate ECFV, where are they located, and what is their mechanism?

Neural stretch receptors - large veins - signals pituitary to regulate AVP/ADH
Atrial stretch receptors - atria - parasympathetic in vagus for AVP secretion - sympathetic firing to kidneys and cardiovascular
Arterial baroreceptors - arteries - signals pituitary to secrete AVP

11

What mechanisms regulate Na excretion?

GFR
Aldosterone
Natriuretic hormone
Renin-Angiotensin system
Sympathetic nerves
Prostaglandins

12

How does arterial pressure regulate Na excretion?

Pressure natriuresis
Reduced Renin
Reduced Angiotensin II
Reduced Aldosterone

13

Where does aldosterone act and what are its actions?

DCT and CD
Increases Na reabsorption
*Relatively slow effect

14

Where does natriuretic peptide (ANP) act and what are its actions?

Renal tubule - inhibits Na reabsorption
Renal vessel - increase GFR / Na excretion
Adrenal cortex - inhibit aldosterone

15

Described the renin-angiotensin system (RAS).

Stimulation - decreased ECFV, BP or increased sympathetic firing
JG cells - alpha 2 globulin -> AT I
Lungs - AT I -> AT II via Angiotensin converting enzyme
Adrenal cortex - increase Aldosterone
AT II - increase proximal Na:H exchanger

16

How do sympathetic nerves affect Na reabsorption?

Decrease GFR
Increase proximal reabsorption

17

Where are prostaglandins, bradykinin, and dopamine produced and how do they affect Na reabsorption?

Kidney
Diuresis / Natriuresis

18

Where is ouabain like factor produced and what is its affect on Na reabsorption?

Atrium
Diuresis
Natriuresis

19

What are the hypovolemic hormones?

AVP
Renin (->AT II-> Aldosterone)
Norepinephrine

20

What is a stronger stimulus of AVP in severe cases, osmolarity or volume?

Volume