Renal Tubules & Urine Formation/Concentration

Question 1

Describe the osmolarity in the renal tubules in relation to water/solutes

Answer 1

Similar composition to plasma

Question 2

T/F Glucosuria is always abnormal

Answer 2

True, glucose should always be reabsorbed

Question 3

List the 3 things that could make a perfect molecule

Answer 3

• freely filtered
• not reabsorbed
• not secreted

Question 4

What are some mechanisms that allow solutes and water to be reabsorbed?

Answer 4

• Passive diffusion
• Active transport
• secondary active transport

Question 5

Describe the electrochemical gradient movement of ions

Answer 5

No movement of sodium due to the charges attracting each other (they stay where they are since they dont want to go down the concentration gradient)

Question 6

Give an example of an adaptive mechanism to maximize reabsorption

Answer 6

1- brush border in proximal tubule
2- peritubular flow
3- peritubular capillary pressures

Question 7

The peritubular capillaries’ adaptive mechanism results in the net transport of water/solutes into or out of them?

Answer 7

Into the peritubular capillaries

Question 8

what part of the nephron is the area with most reabsorption?

Answer 8

Proximal tubule

Question 9

What is needed in the proximal tubule to move filtrate?

Answer 9

Blood supply and ATP

Question 10

Sodium is usually (secreted/reabsorbed) in the proximal tubule?

Answer 10

Reabsorbed via Na/K ATPase

Question 11

Where is the Na/K/ATPase pump located in the cell?

Answer 11

Basolateral membrane

Question 12

Why is Na resorption favored in the tubule?

Answer 12

Because of the gradient created across the luminal membrane by the pump

Question 13

Describe how sodium can manipulate the concentration gradient of other susbtances

Answer 13

it has an osmotic draw (water follows it)

Question 14

The sodium gradient can generate _____________ to reabsorbe glucose

Answer 14

energy

Question 15

What pairs NA and glucose to be transported across luminal membrane?

Answer 15

SGLT2

Question 16

What allows passive diffusion of Na/glucose across basolateral membrane?

Answer 16

High glucose concentration in the cell

Question 17

What is an effect seen with saturated SGLT2 receptors?

Answer 17

Glucosuria (glucose in urine)

Question 18

T/F the loop of henle has a brush border

Answer 18

False

Question 19

Which part of the loop of Henle is permeable to water?

Answer 19

Thin descending

Question 20

The thin ascending limb of the Loop of Henle is (impermeable or permeable) to water

Answer 20

impermeable

Question 21

Which part of the Loop of Henle is high in metabolic activity?

Answer 21

Thick ascending

Question 22

What is the overall charge in the lumen of the thick ascending Loop of Henle?

Answer 22

Positive

Question 23

T/F the thick ascending loop of Henle is impermeable to water

Answer 23

True

Question 24

Describe osmolarity in the Loop of Henle

Answer 24

Hyperosmolar interstitium

Question 25

The descending loop is permeable to water to allow tubular fluid to?

Answer 25

equilibrate with surrounding interstitium

Question 26

Where in the Loop of Henlse is the fluid very concentrated with low flow?

Answer 26

Vasa recta

Question 27

What is the goal of the loop of Henle?

Answer 27

Manipulate medullary interstitium for the gradient

Question 28

The ____________________ is the diluting segment of the nephron.

Answer 28

early distal convoluted tubule

Question 29

The macula densa and juxtaglomerular cells are in the ?

Answer 29

early distal convoluted tubule

Question 30

The final impact on the electrolyte concentration and the pH is done in?

Answer 30

late distal tubule/cortical collecting duct

Question 31

What determines the electrolyte/pH in the late distal tubule?

Answer 31

BP and electrolyte balance

Question 32

The permeability of water in the medullary collecting duct depends on ?

Answer 32

ADH

Question 33

If ADH is present, describe urine formation?

Answer 33

less urine formed (water is reabsorbed)

Question 34

From where is ADH released?

Answer 34

Hypothalamus

Question 35

Would urine be more or less concentrated with ADH?

Answer 35

more concentrated (increased aquaporins=more water reabsorbed)

Question 36

What part of the nephron determines urine concentration?

Answer 36

collecting duct