Reabsorption, Secretion, and Excretion

Question 1

What is the site of most reabsorption?

Answer 1

Proximal Tubule (80%)

Question 2

Reabsorption of glucose, amino acids, phosphates, and even secretion of H+ all depend on what?

Answer 2

Sodium Ion Concentration Gradient
(Secondary Active Transport)

Question 3

What is the Sodium concentration inside of a cell?

Answer 3

Almost Zero

Question 4

What disease can cause glucose transporters to become saturated?

Answer 4

Diabetes Mellitus

Question 5

What happens when glucose transporters become saturated?

Answer 5

Glucose stays in the tubule
(MORE URINE)

Question 6

What blood glucose level do you start to see glucose in the urine?

Answer 6

200mg/dL

Question 7

At what blood glucose level do you see complete saturation of the transporters?

Answer 7

400mg/dL

Question 8

What portion of the Loop of Henle is permeable to water for reabsorption?

Answer 8

Thin Descending Limb

Question 9

What portion of the Loop of Henle is permeable to ions for reabsorption?

Answer 9

Thin Ascending Limb

Question 10

What happens if you block the Sodium/Potassium/Chloride cotransporter in the ascending limb?

Answer 10

Decreased reabsorption
Decreased fluid volume
Decreased blood pressure
Decreased potassium

Question 11

What are some examples of drugs that block the Sodium/Potassium/Chloride contrasnporters?

Answer 11

Furosemide (Lasix)
Bumetanide

Question 12

Where at in the kidney is osmolarity the highest?

Answer 12

Medulla

Question 13

What is the significance of different permeability to salts and water in the ascending and descending Loop of Henle?

Answer 13

Nephron is permeable to water on the descending side and permeable to ions on the ascending side. This allows for a highly concentrated medulla at the bottom and a dilute outer cortex.

Question 14

How does the movement of urea affect the concentration gradient?

Answer 14

Urea affects the concentration gradient because it is allowed to leave (be reabsorbed) in the collect duct.
1. ADH increase the reabsorption of Urea in the lower Collecting Duct
2. ADH inserts aquaporins and you reabsorb more water. (So, if you block it, you pee a lot)

Question 15

What do thiazide diuretics do?

Answer 15

Block Na/Cl Cotransporter
(Distal Tubule)

Question 16

What does aldosterone do?

Answer 16

Increase sodium reabsorption
Increases Potassium excretion
(increases blood pressure)

Question 17

How would a medication that blocks aldosterone-mediated insertion of sodium channels and sodium potassium pump decrease blood pressure and fluid volume?

Answer 17

If you stop reabsorbing sodium, it will increase the amount of Potassium that is going to stay in the body.

Question 18

What medication is a Potassium Sparing diuretic?

Answer 18

Spironolactone

Question 19

What does the Hydrogen/Potassium exchanger do in the kidneys?

Answer 19

Move hydrogen out
Reabsorbs Potassium

Question 20

What happens to Potassium levels when Hydrogen levels are low (Metabolic Alkalosis)

Answer 20

Low Hydrogen = Low Potassium

Question 21

What type of patients have high potassium levels?

Answer 21

Dialysis Patients
(High Hydrogen = High Potassium)

Question 22

How does cell lysis affect Potassium?

Answer 22

Hyperkalemia
(potassium that was inside the cell is now outside)

Question 23

What type of treatments cause cell lysis and hyperkalemia?

Answer 23

Chemotherapy
Radiation

Question 24

Why might a severely hyperkalemic patient be administered insulin to decrease potassium levels?

Answer 24

Increasing insulin will lower blood Potassium because it moves it into the cell.

Question 25

What would a sodium/glucose co-transporter inhibitor do in the kidney? (Canagliflozin)

Answer 25

Prevent Reabsorption of Glucose and Sodium
(Lowers blood sugar by peeing glucose out)