Reg of Na Balance & ECF Vol - Rao

Question 1

What determines plasma volume?

Answer 1

ECFV

Question 2

What does plasma volume determine?

Answer 2

Mean circulatory filling pressure; therefore, cardiac output

Question 3

What are the determinants of ECFV?

Answer 3

1. Na+ Balance (directly proportional to total body Na Content
2. ECFV is independent of Pna

Question 4

What keeps Pna constant usually?

Answer 4

AVP-mediated water excretion by the kidneys

Question 5

When does change in Pna occur?

Answer 5

Only when gain or loss of Na exceeds thirst mechanism and Kidney’s ability to correct the situation

Question 6

What is your daily intake of sodium?

Answer 6

8-15 mgs or 150-250 meq

Question 7

What are the three mechanisms of sodium loss and what percentage does each take care of?

Answer 7

Skin 0-20%
GI - 0.5-10 - diarrhea, vomiting
Renal - 80-90%

Question 8

What are the consequences of sodium retention?

Answer 8

Retention of one day’s intake leads to retention of 1 L of water to maintain isotonicity. Increase in body weight by 1 kg (2.2 lbs)

Question 9

What are things that can lead to a Na imbalance?

Answer 9

diarrhea, vomiting, excessive sweating, diuretics (i.e. bulimics abusing diuretics)

Question 10

How many meq/day of Na are reabsorbed in the proximal tublue?

Answer 10

16000 (64% of filtered Na)

Question 11

How many meq/day of Na are reabsorbed in the Loop of Henle?

Answer 11

7000 (28%)

Question 12

How many meq/day of Na are reabsorbed in the distal tubule?

Answer 12

1750 (7%)

Question 13

What are signs of a ecfv deficit?

Answer 13

Decreased in systemic bp (hypotension)

evident when standing, only when PV is significantly reduced.

Question 14

What are signs of moderate to severe ecfv expansion?

Answer 14

Edema (lower limbs), requiring increase of 2.5-3 L

Question 15

What can can a moderate to severe ecfv increase?

Answer 15

congestive renal failure, heart failure

Question 16

What causes a more severe increase in ECFV?

Answer 16

Pulmonary edema

Question 17

What heart sound is present in ecfv expasion?

Answer 17

s3 gallop, due to progressive increase in venous congestion

Question 18

What physically can be seen in a person with ecfv?

Answer 18

distension of large veins in neck

Question 19

When do you see edema with normal or low ecfv?

Answer 19

hypo-albuminemia

Question 20

Explain the pathway that hypo-albuminemia causes edema/

Answer 20

dec albumin - dec colloid osmotic pressure - flux of fluid into isf - edema

Question 21

What is a rapid response to plasma osmolarity change?

Answer 21

When someone has increased water intake, it produces diuresis, rapidly decreasing urine osmolarity to compensate. Once balance is restored, urine osmolarity will increase.

Question 22

Does a small or large change have to present in plasma osmolarity for the body to decrease urine osmolarity?

Answer 22

a very small change in plasma osmo will lead to a huge change in urine osmol

Question 23

What is a slow response to plasma osmolarity changes?

Answer 23

Renal Na+ excretory system (which takes 2-4 days)

Question 24

Does increase salt increase decrease or increase ecfv?

Answer 24

increase

Question 25

Hypertension patients are recommended to do what?

Answer 25

cut salt intake

Question 26

Where are the receptors of ecfv located in the body?

Answer 26

localized in large veins atria and arteries

Question 27

What are the neural stretch receptors?

Answer 27

In large veins, they respond to mechanism stretch due to venous distention. Signals to pituitary gland to regulate AVP/ADH -> regulates renal Na excretion

Question 28

What are atrial stretch receptors?

Answer 28

Respond to distention, sends central signal via parasympathetic fibers in vagus nerve: variety of centers that are associated with AVP secretion, sympathetic firing to kidneys and cv centers

Question 29

What does ANP do?

Answer 29

regulate renal Na excretion

Question 30

How does each of the following affect Na:

GFR
Aldosterone
Natriuretic Hormone
Renin-Angiotensin

Answer 30

Incr GFR - Inc Na excretion
Aldosterone - Inc Ne reabs in DT and CD
Natriuretic Hormone - Decr Na reabsor
Renin-Angio Dec ECFV - Inc Na Reabso

Question 31

If a change in GFR is very low, how can you determine that there has been a change

Answer 31

An increase in Na excretion

Question 32

If you have a 50% increase in BP, how much will urine flow and Na excretion go up

Answer 32

3-5 fold

Question 33

What stimulates Aldosterone secretion

Answer 33

plasma K and angiotensin,

Question 34

Where does aldosterone work

Answer 34

dct and cd, increasing na reabsorption

Question 35

What are the mechanisms of aldosterone?

Answer 35

increase open Na channel in DCT and CD, increase NACL cotrasnporter
Increased synthesis of NKA - increase Na reabsorption and K secretion
Increased syntehsis of Krebs cycle enzy,es - increased ATP synthesis

Question 36

Does aldosterone have a slow or fast effect on Na reabsorption in dt and cd?

Answer 36

slow

Question 37

What is the opposite of aldosterone? what’s it’s effect

Answer 37

Natriuretic Peptide

increased when Pna increases

Question 38

what are the actions of ANP?

Answer 38

inhibits Na reabsoprtion, Increased GFR and Na excretion, inhitibts aldosterone secretion

Question 39

Where does renin come from?

Answer 39

JG cells

Question 40

what are the direct effects of angiotensin ii?

Answer 40

stimulates aldosterone release from adrenal cortex and induces na reabsorption

Question 41

He has two great charts that lay everything out for you

Answer 41

yea