Phys 4

Question 1

Where is the Na/K ATPase located exclusively?

Answer 1

the basolateral membrane

Question 2

Sodium transport is almost always…

Answer 2

active and via transcellular route

Question 3

Sodium reabsorption mainly occurs via..

Answer 3

Na+ leak channels

Question 4

What is the function of carbonic anhydrase?

Answer 4

it catalyzes the conversion of CO2 and H2O to bicarb and H+

Question 5

Why does the concentration of chloride rise along the PCT?

Answer 5

because water and Na+ are leaving, and it’s staying (starts at 100mmol/L and goes to 120mmol/L)

Question 6

Where do we find AQP1? AQP2? Which is under the control of ADH?

Answer 6

1. PCT
2. CD
3. CD

*Aquaporins control trans cellular movement of water

Question 7

What aquaporins are found in the ascending lim of the Loop of Henle?

Answer 7

NONE NONE NONE—> tons of tight junctions + no aquaporins = impermeable to H2O

Question 8

What is responsible for glucose reabsorption?

Answer 8

90% SGLT2, 10% SGLT1

SGLT2–>low affinity, high capacity
SGLT1–>high affinity, low capacity (why it’s at the end; not much glucose left, but it can find the ones that are)

Question 9

What is a treatment for diabetes?

Answer 9

SGLT2 inhibition (blood glucose levels drop because you don’t reabsorb the glucose)

Question 10

What is the transport maximum for glucose?

Answer 10

200mg/dl

-past this point, extra glucose is excreted (glycosuria)

Question 11

Of all the particles that enter the ascending limb, what percentage are reabsorbd?

Answer 11

75%

Question 12

What is the permeability of the DCT to water?

Answer 12

DCT is relativity impermeable to water

Question 13

What do thiazide diuretics work on?

Answer 13

• they block the Na/Cl pump in the DCT, and this increases the excretion of Na/Cl
• enhance Ca reabsorption in the DCT by increasing Na/Ca exchange
• reduce urinary excretion of Ca (and can be used to treat kidney stones/osteoporosis)

*natriuresis and decreases blood volume and pressure

Question 14

What makes the Collecting Ducts impermeable to water?

Answer 14

lack of ADH

Question 15

What conditions lead to aldosterone being released?

Answer 15

1. decreased blood volume/blood pressure
2. low EC Na+ (hyponatremia)
3. high EC K+ (hyperkalemia)

• 1 and 2 promote renin/RAAS
• *3 directly stimulates adrenal cortex to secrete aldosterone

Question 16

What two structures are impermeable to urea?

Answer 16

DCT, thick ascending limb

Question 17

What is the function of UT-A?

Answer 17

it is stimulated by ADH to increase urea permeability in the inner medullary collecting duct

Question 18

What triggers aldosterone release?

Answer 18

1. angiotensin II (indirect in response to fall in Na+)
2. increased plasma K+

• released from adrenal medulla
• *regardless of 1 or 2, it ALWAYS leads to Na+ reabsorption and K+ excretion

Question 19

Loop Diuretics (furosemide)

Answer 19

MOA: inhibits Na/K/Cl co transporter in thick ascending LoH

• decreases reabsorption of Na, K, CL
• diuresis–>increases urine output (treat edema)

Question 20

K+ sparing spironolactone

Answer 20

MOA: aldosterone dependent K+ sparing diuretic

• inhibits Na/K exchange in distal tubule and collecting duct
• promotes K+ retention of Na+ and water loss
• hypotensive effect