Ion transport

Question 1

What percentage of salt is reabsorbed in the proximal convoluted tubule?

Answer 1

67%

Question 2

What is the ideal homeostatic concentration of K+ in the extracellular fluid?

Answer 2

4.2 mEq/L

Question 3

Two different mechanisms cause aldosterone

secretion from the adrenal gland

Answer 3

Increased K+ levels

Angiotensin II

Question 4

What happens to reabsorption when there is a decrease in peritubular hydrostatic pressure?

Answer 4

Increases reabsorption

Question 5

What happens to reabsorption when there is a decrease in peritubular colloid osmotic pressure?

Answer 5

Decreases reabsorption

Question 6

What happens to capillary oncotic pressure as you move from the affarent to efferent arteriole?

Answer 6

Oncotic pressure increases

Question 7

Will a urinary tract infection cause an increase or decrease in net filtration?

Answer 7

increased hydrostatic pressure in the tubule, decreased net filtration

Question 8

Will low albumin cause an increase or decrease in net filtration?

Answer 8

decreased capillary osmotic pressure, increased net filtration

Question 9

What four things can cause K+ to shift into cells?

Answer 9

1. B-agonists
2. Insulin
3. Aldosterone
4. Alkalosis

Question 10

What three things can cause K+ to shift out of cell?

Answer 10

1. Hyperosmolarity (cell shrinks)
2. Exercise
3. Cell lysis

Question 11

What is the average fractional excretion of K+?

Answer 11

10-20%

Question 12

Physiological factors affecting potassium secretion?

Answer 12

1. Intracellular K+

2. Aldosterone

Question 13

Two different mechanisms that cause aldosterone secretion from the adrenal gland

Answer 13

1. Increased extracellular K+

2. Renin –> Angiotensin II

Question 14

K+ losing diuretics

Answer 14

Furosemide

Thiazide

Question 15

K+ sparing diuretics

Answer 15

Amiloride

Question 16

Furosemide

Answer 16

Increased flow, increased NaCl excretion, increased K+ excretion. Na+, K+, Cl- are blocked from from leaving concentrate, so it increases flow and Na+ conc. Then, Na+ will leave nephron and K+ will enter and be excreted

Question 17

Amiloride

Answer 17

K+ sparing, blocks Na+ conductance so it keeps K+ in the bloodstream so it is not excreted.

Question 18

Most Cl- enters the cell actively or passively?

Answer 18

Passively! Na+ moves in and draws water with it. So Cl- concentration becomes greater and it forms a gradient so that it can flow passively.

Question 19

Routes by which molecules pass in and out of tubule

Answer 19

Paracellular (between cells)

Transcellular (through cells)

Question 20

Where are Na+/K+/Cl- transported together? Also the site of action of the ferosimide diuretics.

Answer 20

Thick ascending loop of Henle

Question 21

Where is Na+ transported with Glu, AA? Also the location in which H+ moves out of the cell with Na+ moving in.

Answer 21

Proximal tubule

Question 22

Where are Na+ and Cl- transported together? Also the site of action of the thiazide diuretics.

Answer 22

Distal convoluted tubule

Question 23

Where does net sodium reabsorption occur?

Answer 23

In the thick ascending limb of the loop of Henle

Question 24

Does chloride tend to go through cells or between cells?

Answer 24

Between cells due to the passive gradient that is built up

Question 25

How does insulin drive K+ into cells?

Answer 25

Indirectly by stimulating the Na+/H+ antiporter. So, Na+ moves into cell, which activates the Na+/K+ ATPase pump.

Question 26

In the late distal tubule, what is secreted by principal cells in order to increase its concentration in the urine?

Answer 26

K+

Question 27

This system keeps plasma K+ levels in check with increasing dietary K+ intake

Answer 27

Aldosterone system

Question 28

Symptoms of Bartter’s syndrome (mutation of Na+/K+/Cl- transporter in thick ascending limb)

Answer 28

Low K+ (K+ losing)
Alkalosis
Polydipsia
Polyuria
Normal to low BP

Question 29

Symptoms of Gitelman’s syndrome (mutation of Na/Cl transporter in distal tubule)

Answer 29

Low K+
Alkalosis
Polydipsia
Polyurea
Normal to low BP

Question 30

Symptoms of Liddle’s syndrome (increased principal sodium channels open)

Answer 30

Low K+
Alkalosis
Hypertension

Question 31

Where does net reabsorption of Na+ occur in the tubule?

Answer 31

In the thick ascending limb of the loop of Henle via the Na/K/2Cl co-transporter