Reg of Na Balance & ECF Vol - Rao Flashcards Preview

Renal Physiology > Reg of Na Balance & ECF Vol - Rao > Flashcards

Flashcards in Reg of Na Balance & ECF Vol - Rao Deck (41)
1

What determines plasma volume?

ECFV

2

What does plasma volume determine?

Mean circulatory filling pressure; therefore, cardiac output

3

What are the determinants of ECFV?

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

4

What keeps Pna constant usually?

AVP-mediated water excretion by the kidneys

5

When does change in Pna occur?

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

6

What is your daily intake of sodium?

8-15 mgs or 150-250 meq

7

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

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

8

What are the consequences of sodium retention?

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)

9

What are things that can lead to a Na imbalance?

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

10

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

16000 (64% of filtered Na)

11

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

7000 (28%)

12

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

1750 (7%)

13

What are signs of a ecfv deficit?

Decreased in systemic bp (hypotension)
evident when standing, only when PV is significantly reduced.

14

What are signs of moderate to severe ecfv expansion?

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

15

What can can a moderate to severe ecfv increase?

congestive renal failure, heart failure

16

What causes a more severe increase in ECFV?

Pulmonary edema

17

What heart sound is present in ecfv expasion?

s3 gallop, due to progressive increase in venous congestion

18

What physically can be seen in a person with ecfv?

distension of large veins in neck

19

When do you see edema with normal or low ecfv?

hypo-albuminemia

20

Explain the pathway that hypo-albuminemia causes edema/

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

21

What is a rapid response to plasma osmolarity change?

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

22

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

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

23

What is a slow response to plasma osmolarity changes?

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

24

Does increase salt increase decrease or increase ecfv?

increase

25

Hypertension patients are recommended to do what?

cut salt intake

26

Where are the receptors of ecfv located in the body?

localized in large veins atria and arteries

27

What are the neural stretch receptors?

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

28

What are atrial stretch receptors?

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

29

What does ANP do?

regulate renal Na excretion

30

How does each of the following affect Na:

GFR
Aldosterone
Natriuretic Hormone
Renin-Angiotensin

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

31

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

An increase in Na excretion

32

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

3-5 fold

33

What stimulates Aldosterone secretion

plasma K and angiotensin,

34

Where does aldosterone work

dct and cd, increasing na reabsorption

35

What are the mechanisms of aldosterone?

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

36

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

slow

37

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

Natriuretic Peptide
increased when Pna increases

38

what are the actions of ANP?

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

39

Where does renin come from?

JG cells

40

what are the direct effects of angiotensin ii?

stimulates aldosterone release from adrenal cortex and induces na reabsorption

41

He has two great charts that lay everything out for you

yea