FINAL EXAM - Lecture 8

Question 1

Osmolarity of proximal tubule should be

Answer 1

Same as plasma osmolarity, since proximal tubule isn’t picky about what it reabsorbs.

Question 2

What is absorbed in ascending thin limb in loop of henle?

Answer 2

NaCl

Question 3

What percent is reabsorbed at TAL? result in osmolarity during water conservation?

Answer 3

25% of solutes are reabsorbed but NO water. Decreased osmolarity cause it dilutes, to 100mOsm/L

Question 4

What is the osmolarity during water conservation of the corner of DCT before it turns to descending? Why does it change from the TAL?

Answer 4

300mOsm/L

H2O can now be reabsorbed, along with NaCl, resulting in increased osmolarity.

Question 5

As we descend down through collecting duct, what happens to osmolarity? Why?

Answer 5

Increases because there can be lots of water reabsorption (dependent upon ADH). H2O, Urea, and NaCl are reabsorbed here.

Question 6

Urine osmolarity in the tubules is the same as ______

Answer 6

Renal interstitium osmolarity.

Question 7

The tubules cant concentrate the tubular urine more than the _____.

Answer 7

Interstitial osmolarity.

Question 8

During water excess and we want to get rid of it, the proximal tubule osmolarity will be

Answer 8

Still 300…

Question 9

During water excess, the loop of henle osmolarity will be

Answer 9

600mOsm/L

Question 10

Why is osmolarity lower in loop of henle during water excess? What SPECIFICALLY causes the decrease?

Answer 10

Less ADH, means less Urea in interstitium, means less water reabsorption.

Question 11

Tubular osmolarity after TAL in water excess?

Answer 11

100mOsm/L in tubular, but 300 in interstitial space.

Question 12

During water excess, the end of the collecting duct can reach what osmolarity?

Answer 12

50

Question 13

Path of Na, Cl, and K concentration as it moves through tubule

Answer 13

Starts off staying the same in proximal tubule, and as it goes down descending thin limb it will increase in concentration because water is being reabsorbed but not much NaCl. But once it reaches TAL, concentration will drop because water isn’t being reabsorbed but electrolytes are. Once it reaches distal tubule, concentration slightly increases for NaCl from there until excretion. K+ is different here. Once distal tubule starts, concentration increases faster due to water and NaCl reabsorption, but not K. It will increase very fast until excretion.

Question 14

Similarities and differences of creatinine, inulin and PAH with concentration levels throughout the tubule

Answer 14

PAH will have higher concentrations, but they mostly follow the same pattern. PAH increases from 1.0 at beginning, to 585 by end of collecting tubule. Creatinine and inulin increases from 1.0 to 140 and 125.

Question 15

Typically, all diuretics will cause excretion of fluid from body. The fluid typically comes from what compartment?

Answer 15

Extracellular

Question 16

Diuresis means you are excreting _____ things, which are ______

Answer 16

2; Water and electrolytes

Question 17

Extracellular fluid is proportioned into plasma and interstitium. What percent is plasma and what percent is interstitium?

Answer 17

1/5th plasma, 4/5th interstitium.

Question 18

If we remove a liter of fluid from extracellular compartment, how much of that leaves the cardiovascular system?

Answer 18

Only 200mL.

Question 19

When you start and keep a patient on a diuretic, how do the conditions of the fluid and electrolyte status change throughout therapy?

Answer 19

Initially, there is a fluid drop.. Once patient stays on diuretic, it’s just maintaining current conditions unless you change the dose or drug.

Question 20

Long term therapy for chronic hypertension that relax blood vessels, will result in

Answer 20

The body will adjust, and may need diuretic therapy added on. The relaxation of blood vessels is nice, but the body will adapt to that. Diuretics can help maintain that blood pressure therapy at a constant clip.

Question 21

If someone has normal kidneys, salt intake will result in

Answer 21

A direct increase in suppression of angiotensin II to remove salt at an exact rate.

Question 22

IF we have high levels of angiotensin II, and we have high salt intake, it will result in

Answer 22

High blood pressure.

Question 23

If we have angiotensin blockage, we would have low _____, causing a problem with ____

Answer 23

Aldosterone; salt reabsorption, leading to low blood pressure.

Question 24

If someone is on an ACE-i in the OR, then it will be difficult to ___

Answer 24

Manage blood pressure in OR. Not recommended to tell patient to stop taking their blood pressure medication, just have to adjust.

Question 25

If someone has a terrible diet and eats little Caesar’s everyday (high salt), then our body will compensate by

Answer 25

Getting rid of angiotensin II. It’s the same exact thing as having an ace inhibitor, and will be an issue in the OR!

Question 26

Things that’s can cause high angiotensin II problem

Answer 26

Renal artery stenosis: The stenosis causes low blood pressure beyond the stenosis in the kidney, resulting in low GFR. The low GFR results in macula densa sensing that, and increasing ANGII, and reabsorbing NaCl. Increases GFR. This all increases blood pressure, and kidney thinks body has a low BP even though it doesn’t… Even though only one kidney is stenotic, the ANGII acts on both kidneys. The good kidney will attempt to compensate and reduce renin production, but it isn’t close to matching the increase that the bad kidney does.

Question 27

How can you treat renal stenosis?

Answer 27

Possibly a stent, but you can use ACE-i, ARBs (-tans), renin-inhibitor. Earlier the better!

Question 28

The renal stenosis will raise the systemic blood pressure, we’ve established that. If the healthy kidney has a high MAP, what happens?

Answer 28

Increased Pcap, increased GFR. It will try to compensate by constricting afferent arteriole. Can destroy glomerular capillary beds.

Question 29

How does salt work with food and your taste of it?

Answer 29

Enhances ability to taste flavors.

Question 30

Structure of a taste bud and how it works with channels

Answer 30

Electrically excitable, with Na+ and K+ channels. No Cl- channels!!!!!

Has a sensor to taste things, and this sensor changes cell permeability.

If you increase amount of Na+ around taste sensor, it will make the cell more excitable, which makes the cell easier to excite, and food easier to taste :)

Cl- is normally inhibitory, but since taste buds dont have Cl- channels, it cant inhibit!

Question 31

If you’re on a low-salt diet, what is used instead of salt?

Answer 31

K+, and it’s super strong, dont need much. It tastes gross, too.

Question 32

If we eat a diet thats high in salt intake, it will increase our desire to ____. What are the overall effects?

Answer 32

Drink water.

Increased plasma sodium concentration, and will increase blood volume.

It will also increase sodium in glomerular filtrate, and more sodium being filtered means more that the macula densa senses, and repress renin release/angiotensin too. It will also drop aldosterone, and all of this will help you get rid of excess salt.

higher blood volume means higher BP, which means higher Pcap, which increases filtration rate, and more Na+ to macula densa, which will ALSO lower everything as mentioned above.

Question 33

With increasing intake of salt, and someone with a normal blood pressure, the blood pressure will

Answer 33

very very slightly raise. The graph shows a very slight increase in MAP with increased salt intake, but its almost straight up and down.

Question 34

If you have essential hypertension, and you increase your salt intake, the blood pressure will

Answer 34

very slighty increase, not much of a difference.

Question 35

If you have salt-sensitive hypertension, and you increase your salt intake, the blood pressure will

Answer 35

increase with sodium intake, obviously!

Question 36

What causes salt-sensitive hypertension?

Answer 36

Renal-vasculature hypertension. A stenotic renal artery can cause this, cause there is over-expression of angiotensin II in the system already, and extra salt will be reabsorbed.

Question 37

What kind of hypertension do african-americans have?

Answer 37

Salt-sensitive.

Africans-africans DONT have this.

also prevalent in some parts of asia.

Question 38

Whats causing the salt-sensitive hypertension in african-americans?

Answer 38

LOW-RENIN hypertension. Which is opposite of what you would expect… But its still effective to treat with ace-inhibitor even though there isnt much to inhibit!

Question 39

What kind of diuretic is mannitol?

Answer 39

Osmotic

Question 40

Give examples of osmotic diuretics and why they work

Answer 40

Mannitol: It gets filtered but not reabsorbed. For every molecule of mannitol in tubule, is one less water reabsorbed.

Excess Blood glucose also acts as an osmotic diuretic, as water hangs onto it.

Vitamin C will also work as an osmotic diuretic!

Question 41

How do ARBs work?

Answer 41

-tan drugs. Inhibit the constriction of efferent arteriole, and how much salt is reabsorbed in proximal tubule. If AT1 receptor isn’t used as much, means less sodium reabsorption.

ACE inhibitors do the same thing.

Question 42

How do K sparing diuretics work?

Answer 42

Affect aldosterone portion of principal cells.

Question 43

Normal blood concentration of creatinine

Answer 43

1mg/dL

Question 44

How much mg of creatinine do we filter each minute if our GFR is 125mL/min? What is this called?

Answer 44

1.25mg, filtered load.

Question 45

How much creatinine is normal secreted per minute?

Answer 45

0.15mg/min

Question 46

What is the total excretion of creatinine per minute?

Answer 46

1.25mg + 0.15mg = 1.40mg/min

None of it is reabsorbed, so you dont need to subtract anything.

Question 47

Creatinine is a byproduct of

Answer 47

Skeletal muscle metabolism

Question 48

Since creatinine is constantly being produced by skeletal muscle, then production rate should equal

Answer 48

Excretion rate

Question 49

1.25mg/min of creatinine is being filtered through how many nephrons?

Answer 49

It’s the total of 2 million nephrons if we are healthy under the age of 40.

Question 50

If we have 1.25mg/min of creatinine filtered per minute with 2 million nephrons (2 healthy kidneys), what would happen if we lose a kidney?

Answer 50

Originally would drop down to half as much filtered.. 0.625mg/min

Question 51

What happens to plasma creatinine once 1 kidney is lost?

Answer 51

It’ll double in the plasma concentration.

Question 52

When you lose a kidney, and GFR and creatinine filtration is cut in half, how long does it take to return to normal? And how?

Answer 52

A bit over 2 days to recover. The body has to pack twice as much creatinine into the same amount of fluid as before, that way the creatinine still gets removed at the same rate of production. GFR doesn’t change immediately, but does eventually. Plasma creatinine DOES NOT CHANGE!!!!!! It stays doubled on purpose!

Question 53

How does the remaining kidney adapt after the other one is removed?

Answer 53

Physiologic hypertrophy to raise GFR. Takes about a year to adapt. It does not destroy itself and it’s a good thing, and it’s not similar to diabetic induced hypertrophy. It compensates its GFR by about 50%.

Question 54

If the drugs and stenting aren’t effective at helping with renal stenosis in bad kidney, what’s the best thing to do?

Answer 54

Sometimes it’s best to remove the bad kidney before it destroys the good kidney.

Question 55

What’s the GFR of a single nephron?

Answer 55

62.5 nl/min

(nl/min = nanoliter)

Question 56

What is the volume excreted per 1 single nephron?

Answer 56

0.75nl/min

Question 57

If we lose 75% of our nephrons, then our GFR will be what and what dictates that?

Answer 57

40ml/min

But it depends what causes the decrease… if there’s good physiologic hypertrophy, then yes it can compensate up to 40ml/min. If its from chronic hypertension then no it wont compensate as well and will be lower than that.

Question 58

What’s the single-nephron GFR when you lose 75% of your nephrons and they have the ability to compensate for the loss?

Answer 58

80nl/min

Question 59

What’s the volume secreted per single nephron when they can compensate for 75% loss of nephrons?

Answer 59

3.0nl/min

Up from .75nl/min

Question 60

what is the volume excreted for ALL nephrons when there is 75% loss of nephrons that compensate well?

Answer 60

Still 1ml/min.

The workload will damage these remaining nephrons over time due to being overworked, and will lower their life expectancy. That’s why CKD progresses quickly. The more that die… the more overworked the remaining ones are.

Question 61

Treatments for renal failure

Answer 61

Na+/K+ restriction (so they dont have to filter as much with remaining nephrons)
Volume restriction
Protein restrictions (amino acids being reabsorbed takes a lot of work)
Diuretics, dialysis, CRRT
NO NSAIDS
ARBS/ACE-i
Manage T2DM closely
Synthetic vitamin D and EPO

Question 62

Problems associated with renal failure

Answer 62

Hypervolemia, hypernatremia, hypervolemia, hypertension, hypocalcemia, acidosis (cant get rid of protons as well, but they can get rid of bicarbonate still if the conditions are right)

Anemia, hyperphosphatemia, uremia (azotemia, nitrogenous compounds)

Question 63

In a normal state, osmolarity is ____ and what percent is intracellular fluid and what is extracellular?

Answer 63

300

2/3rds intracellular, 1/3rd extracellular

Question 64

If you added isotonic NaCl, what happens to osmolarity and fluid balance?

Answer 64

Doesn’t change osmolarity, as its same as what the body should be. It will just increase extracellular fluid.

Question 65

If you added hypotonic NaCl into the IV, which is 0.45% NS, what happens to osmolarity and fluid compartments?

Answer 65

It will decrease osmolarity, because you’re adding more water than salts and it will dilute the fluid in ALL compartments. It will increase size of intracellular compartments and extracellular at the same proportion of their size. osmolarity will balance itself so it moves everywhere.

Question 66

If you added a hypotonic NaCl thats 250mOsm/L to someone in their CV system with an osmolarity of 300, what happens?

Answer 66

It would diffuse into intracellular compartments until both compartments are 275mOsm/L

Question 67

If you add hypertonic NaCl (3% saline), we are adding more salts than water, which would do what to osmolarity and fluid compartments?

Answer 67

Raise osmolarity in both intracellular and extracellular, and fluid would be pulled from intracellular compartment into the extracellular compartment, because the salts in the extracellular compartment will want more water until osmolarity is balanced.