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Flashcards in Renal Physiology Deck (77)
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1

HP = hydrostatic pressure is due to what? 2

Describe it in the capillary? (where does the fluid go and at what pressure?) 3

IN the intersitial fluid? 2

1. Due to fluid pressing against a wall
2. “Pushes”

In capillary (HPc)
1. Pushes fluid out of capillary
2. 35 mm Hg at arterial end and
3. 17 mm Hg at venous end of
capillary in this example

In interstitial fluid (HPif)
1. Pushes fluid into capillary
2. 0 mm Hg in this example

2

OP = osmotic pressure is due to what? 1

In capillary (OPc) where does the fluid go and at what pressure? 2

In interstitial fluid (OPif) where does the fluid go and at what pressure? 2

1. Due to presence of nondiffusible
solutes (e.g., plasma proteins)

1. Pulls fluid into capillary
2. 26 mm Hg in this example

1. Pulls fluid out of capillary
2. 1 mm Hg in this example

3

FP (net filtration pressure) in the arteriole is ___ mm Hg; fluid moves ____?

10

out

4

NFP in the venule side is __ mm Hg;
fluid moves___?

~8
in

5

Abnormalities of Extracellular
Fluid Na+ Concentration:
1. Hypernatremia affects Na+ levels and water levels how?

2. Hyponatremia affects Na+ and water levels how?

3. What is normal plasma Na?

1. water loss, Na+ excess
2. Water excess, Na+ loss

3. 140-145 mmol / L

6

Consequences of Hyponatremia and Hypernatremia: Water moves in or out of cells → cells swell or shrink. This has profound effects on the brain.
1. Rapid shrinking?
2. Rapid swelling? (Why does the brain herniate so easily?)

1. Rapid shrinking can tear vessels and cause hemorrhage
2. Rapid swelling can cause herniation
-Because the skull is rigid, the brain cannot increase its volume by more than 10% without herniation.

7

Extracellular hypertonicity 1._______ expression of gene encoding proteins that 2.________ intracellular osmoles.

What are these encoding proteins? 2


What is the clinical significance of this?
-rapid changes vs slow changes

1. increases
2. increase

1. Membrane transporters (Na+-H+- exchanger)
2. Enzymes (e.g. aldose reductase that synthesize intacellular solutes e.g. sorbital)

Clinical significance: Rapid changes in extracellular fluid tonicity alter cell volume and cause neurologic complications, while slow changes have much less effect on cell volume and much less clinical effect.

8

1. Normal plasma volume?
2. Normal interstitial fluid volume?
3. Intracellular fluid volume?

1. plasma 3 L
2. IF 11 L (so extracellular is 14 L)
3. Intracellular 28L

9

1. What is fluid intake regulated by? 2
2. What is electrolyte intake governed by? 1
3. What is fluid output regulated by? 1
4. What is electrlyte output regulated by? 1

1. Fluid Intake: regulated by thirst mechanism, habits
2. Electrolyte intake: governed by dietary habits

3. Fluid Output: regulated mainly by kidneys
4. Electrolyte output: regulated mainly by kidneys

10

What does the posterior pituatary release that signals water reabsorption in the collecting ducts of the kidneys?

ADH

11

What signals the posterior pituitary to release ADH?

increased osmolarity and Na+ concentration in the plasma stimulates osmoreceptors in the hypothalamus. This stimulates the pituitary

12

Describe the flow of blood flow from the heart to the kidney's
15

1. Aorta
2. renal artery
3. segmental artery
4. interlobar artery
5. arculate artery
6. cortical radiate artery
7. afferent artiole
8. Glomerulus (capillaries)
9. efferent artioles
10. peritubular capillaries and vasa recta
11. cortical radiate vein
12. arcuate vein
13. Interlobar vein
14. renal vein
15. IVC

13

Which part of the nephron has intercalated cells?

collecting duct

14

What is the formula for excretion?

Excretion = filtration - reabsorption + secretion

15

The kidney produces urine through 4 steps

1. Glomerular filtration
2. Tubular reabsorption
3. Tubular secretion
4. Concentration

16

1. WHat does glomerular filtration create?

2. What does tubular reabsorption remove?

3. What does tubular secretion remove?

4. What does the concentration remove?

1. creates a plasmalike filtrate in the blood

2. removes useful solutes from the filtrate, returns them to the blood

3. removes additional wastes from the blood and adds them to the filtrate

4. removes water from the urine, concentrates wastes

17

What happens at the proximal convoluted tubule?

reabsorption of water, ions, and all organic nutrients

18

What happens at the distal convoluted tubule? 2

Secretion of ions, acids, drugs and toxins.

Variable reabsorption of water, Na ions, and calcium ion (underhormonal control)

19

What is the function of the renal corpuscle?

production of filtrate

20

What is the purpose of the loop of henle?

Further reabsorption of water (descending limb) and both sodium and chloride ions (ascending limb)

21

Collecting System:
What is the purpose of the collecting duct?

What is the purpose of the papillary duct?

1. Variable reabsorption of water and reabsorptionor secretion of sodium, potassium, hydrogen, and bicarbonate ions

2. Delivery of urine to the minor calyx

22

What is clearance?



Renal clearance specifically?

is a general concept that describes the rate at which substances are removed (cleared) from the plasma.

of a substance is the volume of plasma completely cleared of a substance per min by the kidneys.

23

Cs x Ps = Us x V
What does each mean?

Cs = clearance of substance S
Ps = plasma conc. of substance S
Us = urine conc. of substance S
V = urine flow rate

Cs = Us x V
Ps

24

For a substance that is freely filtered, but not reabsorbed or
secreted (inulin, 125 I-iothalamate, creatinine), renal clearance
is equal to what?

GFR

25

What is the equation for GFR?

GFR = (Uin x V)/Pin

26

WHat does Ccr = ?

GFR

27

Theoretically, if a substance is completely cleared from
the plasma, its clearance rate would equal what?

renal plasma flow

Cx = renal plasma flow

28

1._____________ _____ is freely filtered and secreted
and is almost completely cleared from the renal plasma

2. Whats the equation?

3. To Calculate Actual RPF , One Must Correct for what?

1. Paraminohippuric acid (PAH)

2. ERPF = Upah x V/Ppah

3. Incomplete Extraction of PAH

29

HOw do we calulate Epah?

How do we calculate RPF?

Apah- Vpah/Apah

RPF = ERPF/Epah

30

The Filtration Membrane
From the plasma to the capsular space, fluid passes through three barriers. What are they?

1. foot processes
2. fenestrated epithelium
3. Basement membrane