Lecture 11/22: Renal Physiology Cont'd

Question 1

Where can we reabsorb water in the nephron?

Answer 1

PCT
TAL
DCT
Collecting duct

Question 2

What is the osmolarity of the diluting segment

Answer 2

100 mOsm/L

Question 3

Osmo in the PCT should be ______ to the plasma filtered

Answer 3

about equal

Question 4

What is the pathology for hyponatremia?

Answer 4

This is decreased plasma Na+ osmo

Decreased ADH levels –> decrease urea reabsorption at the collecting duct –> dilute renal ISF & decreased AQP2 channels in the apical cell wall –> ions still being reabsorbed but not water –> increased water excretion

Question 5

Where would you see a decrease in plasma osmo of Na+, K+, & Cl+?

Answer 5

End of the TAL in the loop of henle

Question 6

PAH is increased in the nephron _____x

Answer 6

528

just know that its freely filtered & heavily secreted

Question 7

Where would you see a dip in plasma osmo of creatinine/inulin?

Answer 7

last part of the loop on henle

Question 8

What does diuresis mean?

Answer 8

Di = 2

Taking out ions & water

Question 9

Where is the fluid excreted from diuretics coming from? How is it divided?

Answer 9

Extracellular fluid

Plasma 20%

ISF 80%

Question 10

Explain the breakdown of excretion of 1L from a diuretic

Answer 10

1L of ECF

ECF: Plasma = 1/5
ISF = 4/5

Therefore: 200cc of Plasma was excreted
800 cc of ISF was excreted

Question 11

T/F: Diuretics increase the amount of fluids we lose each day

Answer 11

F

It maintains the initial amount that we first took the drug

If we want to take off more fluid we have to increase the dose

Question 12

Why are diuretics better for long term BP management than vasodilators?

Answer 12

With long term vasodilation, the body will find a way to work around that

Ex) with the nervous system: If it cant get the job done with Epi/NE –> releases ADH/ANGII to go around vasodilator

Question 13

How much is total body water?

Answer 13

TBW is 60% of body mass

Question 14

How do you find the the amount of ICF?

Answer 14

2/3 of TBW

Question 15

How do you find the amount of ECF?

Answer 15

1/3 of TBW

Question 16

What is considered ECF?

Answer 16

ISF and plasma

Question 17

How do you find the amount of plasma?

Answer 17

ECF x (1/4) - ECF (1/5)

Question 18

How do you find the amount of ISF?

Answer 18

ECF minus plasma

Question 19

What are the values for TBW, ICF, ECF, Plasma, and ISF in a 70kg person?

Answer 19

TBW = 42 LITERS
ICF = 28 L
ECF = 14 L
Plasma = 2.8 - 3.5 L (Going to use 3L)
ISF = 11 L

Question 20

Describe the pathology for chronically high ANGII. What is the treatment for this?

Answer 20

If salt intake increase = BP increases & increased filtration in kidneys

Cant suppress ANGII system
Increased salt will also increase water & raise BP
THIS IS A SYSTEMIC PROBLEM

Tx: decrease salt & water intake

Question 21

Describe the pathology for Angiotensin II blockade. What is the temporary treatment for this?

Answer 21

Difficulty reabsorping Na to keep BP normal –> decreases Aldo as well –> Decreases BP

Temporary Tx: Increase salt intake

Question 22

What is the pathology for 1 kidney becoming stenotic? What is the Tx for this?

Answer 22

Bad Kidney: ↓RBF –> ↓Pressure at GC –> ↓GFR –> ↓Na/Cl at MD –> ↑Renin/ANGII release –> Increase GFR

Good Kidney: ↑Renin/ANGII release effects this kidney too
-↑Pressure at GC –> ↑GFR
-AA will try to constrict to combat but wont be able to fully compensate so pressure still high

Tx: ACE inhibitor (-pril)
ARBs (-sartan)

Question 23

What are surgical options available for the treatment of Renal artery stenosis?

Answer 23

Renal stent

Nephrectomy

Question 24

T/F: A taste bud is an electrically excitable cell

Answer 24

T

Question 25

What channels are on a taste bud?

Answer 25

Na+ K+ **Remember you have some K+ channels on cells than Na**

Question 26

Why does adding salt to food makes things taste better?

Answer 26

It makes the taste bud cell more excitable Na+ binds to its receptor on the taste bud → ↑ its membrane permeability allowing Na+ to come into the cell increasing its mV → ↑ taste

Question 27

What is salt substitute?

Answer 27

K+

Question 28

What is the difference between Essential hypertension & salt-sensitive hypertension?

Answer 28

They're both forms of essential HTN -essential HTN: idiopathic -Salt intake does not increase the BP -salt-sensitive hypertension: overexpression of RAAS -salt intake will increase the BP **Low Renin production** <-- hallmark sign

Question 29

______ HTN is seen more commonly in African Americans and NOT African Africans

Answer 29

Salt-sensitive hypertension

Question 30

What are predisposers of essential HTN?

Answer 30

-Genes <-- primary -diet

Question 31

What is the Tx for salt-sensitive hypertension?

Answer 31

ACE inhibitors (-prils) Maybe ARBs? (-sartans)

Question 32

What are some renal antihypertensive drugs?

Answer 32

-Mannitol -ARBs (-sartans) -ACE inhibitors (-pril) -K+ sparing

Question 33

What compounds can act like an osmotic diuretic?

Answer 33

Excess glucose Excess Vitamin C

Question 34

What are some Tx for renal failure?

Answer 34

Na+ restriction (lots of Na+ pumps in nephron) K+ restriction (K+ secreted alot) Protein restrictions (broken down to amino acids) All these things increase the work of nephrons **There are way more but these were highlighted **

Question 35

What are some problems you'll see with kidney failure?

Answer 35

**Think, why did my pt need dialysis?** Hypernatremia hypervolemia hyperkalemia hypertension acidosis

Question 36

What is the effects on giving isotonic fluids on fluid compartments?

Answer 36

ECF: add volume ICF: No change

Question 37

What is the effects on giving hypotonic fluids on fluid compartments?

Answer 37

EFC: Adds volume; decreases osmo --> water goes into cell ICF: Adds volume; decreases osmo --> water goes into cell

Question 38

What is the effects on giving hypertonic fluids on fluid compartments?

Answer 38

EFC: Adds volume; increases osmo --> water pulled out of cell ICF: decreases volume; increases osmo --> water pulled out of cell

Question 39

What is normal plasma creatinine?

Answer 39

1mg/dL

Question 40

How much creatinine is normally secreted?

Answer 40

0.15mg/min

Question 41

What is the normal excretion rate of creatinine?

Answer 41

1.40mg/min

Question 42

With creatinine, Excretion rate has to equal ________

Answer 42

production rate

Question 43

Creatinine is a byproduct of _______

Answer 43

skeletal muscle metabolism

Question 44

What is normal filtered load of creatinine?

Answer 44

1.25mg/min

Question 45

What happens to creatinine production when we have a nephrectomy? Why does this happen?

Answer 45

Everytime we lose half our nephrons, plasma creatinine has to double **We are still producing the same amount of creatinine = 1.4mg/min.** -We lost 1/2 nephrons: We are now only excreting 0.7mg/min now -The excess that we are producing is BUILDING UP IN THE PLASMA!!!! **-Once the normal plasma creatinine doubles, it will now equal the production rate (The old excretion rate)** Plasma concentration would have to continue to rise until excretion rate equals production rate

Question 46

What is physiology hypertrophy of the kidney?

Answer 46

About a year after a nephrectomy your kidney will get big/stronger --> able to do more work --> increases GFR by 50% **This is only if the remaining kidney is healthy**