Review of Renal Physiology (pgs 1-17 in handout) Flashcards Preview

Pharmacology Unit 4 > Review of Renal Physiology (pgs 1-17 in handout) > Flashcards

Flashcards in Review of Renal Physiology (pgs 1-17 in handout) Deck (47)
Loading flashcards...
1

In a 70kg person, what is the:
TBW?
ICF?
ECF?
Intravascular Fluid?
Extravascular Fluid?
Plasma?

TBW- 42L
ICF-28L (40% of weight)
ECF- 14L (20% of weight)
IVF-4.9L (7% of weight)
EVF-11L (75% of ECF)
Plasma- 3L (25% of ECF)

2

How does body composition change as we age?

-as age increases total body fluid decreases

3

How does the osmolarity of the ECF compare to that of the ICF?

essentially the same (solute composition differs)

4

What do rapid gains and losses in body weight reflect?

a change in total body water

5

What percentage of CO perfuses the kidneys (RBF)?

20% (1-1.2L)

6

What percentage of renal blood flow (RBF) is renal plasma flow (RPF)?

55% (600-700ml)

7

What percentage of renal plasma flow (RPF) is GFR?

20% (125ml)

8

Approximately how many times per day is the ECF volume filtered through the kidney?

10x

9

Approximately what percent of the daily GFR (180L) is excreted in urine?

1-2L/day (0.5-1%)

10

Which solute in the ECF primarily determines ECF volume?

Na+ (more Na, more ECF volume)

11

When ECF volume expands how does the kidney compensate?

increases Na output and therefore water output leading to ECF volume contraction --> compensatory decrease in Na and water output
***This does not change GFR**

12

Severe ECF volume contraction (dehydration) can cause a decrease in what?

GFR

13

How is Na balance regulated?

by adjusting urine Na output to match Na intake
(Na intake restricted-->gradually increasing Na reabsorption until lower Na output in urine is achieved)

14

What happens to ECF volume when Na intake is reduced?

ECF volume contracts in an amount equivalent to the volume of urine needed to eliminate the excess Na isosmotically

15

An imbalance in hydrostatic and oncotic pressure across the capillary wall inducing a shift of fluid from intravascular space to extravascular space

Edema

16

How does the circulating volume change in edema and what does it do physiologically?

-decreases
-activates the renin-angiotensin-aldosterone system-->increase in sodium retention-->maintenance of the edema

17

All of the following are potential causes of what?
CHF
Liver Disease
Nephrotic Syndrome
Pulmonary Edema

Edema

18

How do diuretics work in treating edema?

they force an increased elimination of Na and water-->decrease in hydrostatic pressure and increase in oncotic pressure-->absorption of edematous fluid

19

Renal Handling equation

Excretion= Filtration - Reabsorption + Secretion

20

What is produced in the glomerulus?

an ultrafiltrate of the blood with similar solute concentration to the plasma (-protein)

21

Where is the proximal tubule located and what is its function?

-in the cortex
-reabsorbs 66% of filtered Na, 67% of K+ and most of filtered Bicarb
-This is a leaky epithelium so reabsorption is isosmotic and 66% of the filtered water is also reabsorbed

22

Where is the loop of henle located and what is its function?

-thin desc. and asc. in med, thick ascend, in medulla and cortex
-25% of filtered Na, and 20% of K+ reabsorbed in thick asc limb by the Na/K/2Cl contransporter w/o water**-->drives the counter current multiplication of interstitial solute concentration

23

Where is the distal tubule located and what is its function?

-in the cortex
-reabsorption of 6% of filtered Na via Na/Cl cotransporter at luminal membrane and Na/K ATPase at basolateral membrane
**Na/Cl cotransporter is target of thiazide diuretics**
-impermeable to water
-late distal tubule-last part of the nephron to control ion composition of the urine

24

Which hormone regulates Na reabsorption and K+secretion in the distal tubule? Water reabsorption?

-aldosterone
-ADH

25

Where is the collecting duct located and what is its function?

-outer cortex and inner medulla
-reabsorption of water induced by ADH

26

What is the filtration fraction?

fraction of plasma flowing through the glomeruli which is ultrafiltered to form tubular fluid (GFR/RPF)
~.20 (20%)

27

How is the fractional excretion of water calculated? (FEwater)

= urine flow rate (V)/GFR
-fraction of glomerular filtrate not reabsorbed from the tubular fluid

28

How can GFR be measured?

=Clearance of inulin= (Urine Inulin)(urine flow rate)/(Plasma inulin)

29

How can the fractional excretion of Na be calculated?

=(Urine Na X Plasma Cr) / (Urine Cr X Plasma Na)

30

When in water and Na balance, approximately how much of the filtered water and Na is in the urine?

1%