RP4: Tubular Reabsorption and Secretion

Question 1

Answer 1

early distal tubule cell

Question 2

Answer 2

alpha intercalated cell

Question 3

Answer 3

early proximal tubule cell

Question 4

Answer 4

Beta intercalated cell

Question 5

Answer 5

principal cell

Question 6

Answer 6

thick ascending limb cell

Question 7

Answer 7

late proximal tubule

Question 8

How can solutes go from the lumen into the tubular cells?

Answer 8

paracellular path
transcellular path

using active or passive (diffusion)

Question 9

How can water go from the lumen into the tubular cells?

Answer 9

osmosis paracellularly or transcellularly

Question 10

How do solutes and water go from the interstitial fluid (basolateral side) to the peritubular capillaries?

Answer 10

bulk flow

Question 11

When something travels from the tubular cell to the capillary via interstial fluid what is the process called?

Answer 11

reabsorption

Question 12

Which membrane of the tubular cell is apical?

Answer 12

facing the lumen

Question 13

Which membrane of the tubular cell is basolateral?

Answer 13

facing the peritubular capillary

Question 14

Once fluid is reabsorbed across the tubule epithelium into the interstitial fluid, it enters peritubular capillaries via…

Answer 14

Bulk Flow

Question 15

The normal rate of Peritubular Capillary Reabsorption is…

Answer 15

124 ml/min

Question 16

Does sodium reabsorption occur Transcellular or Paracellular?

Answer 16

BOTH

Question 17

Sodium reabsorption is passive or active across the apical membrane?

Answer 17

passive

Question 18

Sodium reabsorption is passive or active across the basolateral membrane?

Answer 18

active

Question 19

Why is sodium reabsorption passive across the apical membrane?

Answer 19

the transepithelial potential difference (TEPD) between the tubular lumen and interstitial fluid is -3 mV

Question 20

What is transport maximum?

Answer 20

Maximum rate some substances can be transported across the epithelium (absorption or secretion)

Question 21

What is renal threshold?

Answer 21

plasma concentration that saturates the carrier (tubular load)

Question 22

Reabsorption of water is strickly…

Answer 22

passive (where ever the solutes go the water will follow)

Question 23

__________ highly permeable to H2O

Answer 23

Proximal tubule

Question 24

PT Reabsorption of Na+, Cl-, Urea and H2O exhibit…

Answer 24

Gradient-Time Transport

Question 25

Ascending limb of Loop of Henle is permeable or not to water?

Answer 25

not permeable to H2O

Question 26

If water is reabsorbed to a greater extent than the solute, the solute will become _____ concentrated in the tubule

Answer 26

more ex: creatinine, inulin

Question 27

If solute is reabsorbed to a greater extent than water, the solute will become ____ concentrated in the tubule

Answer 27

less ex: amino acids, glucose

Question 28

What is unique about the cells of the proximal tubule?

Answer 28

- high capacity for active/passive reabsorption - large # of mitochondria - large surface area - high permeability to H2O

Question 29

What does the proximal tubule reabsorb?

Answer 29

65% of... Na+ Cl- HCO3- K+ all glucose all amino acids

Question 30

What does the proximal tubule secrete?

Answer 30

metabolic waste products like H+, bile salts, toxins, drugs, and PAH

Question 31

What type of transport does the early proximal tubule use for Cl-?

Answer 31

paracellulary

Question 32

What type of transport does the late proximal tubule use for Cl-?

Answer 32

- transcellular (apical - secondary active antiporter; basolateral - facilitated diffusion) - paracellular

Question 33

What type of transporters are in the early proximal tubule?

Answer 33

SGLT2 GLUT2

Question 34

What type of transporters are in the late proximal tubule?

Answer 34

SGLT1 GLUT1

Question 35

What type of transporters in the proximal tubule are in the apical membrane?

Answer 35

SGLT2 (early PT) SGLT1 (late PT) - secondary active

Question 36

What type of transporters in the proximal tubule are in the basolateral membrane?

Answer 36

GLUT2 (early PT) GLUT1 (late PT) - facilitated diffusion

Question 37

Where is 90% of the glucose reabsorbed?

Answer 37

early proximal tubule

Question 38

Where is 10% of the glucose reabsorbed?

Answer 38

late proximal tubule

Question 39

What is the affinity and capacity of the early proximal tubule transports (SGLT2 and GLUT2)?

Answer 39

low affinity high capacity

Question 40

What is the affinity and capacity of the late proximal tubule transports (SGLT1 and GLUT1)?

Answer 40

high affinity low capacity

Question 41

What transport inhibitor is used as a treatmetn for type 2 diabetes?

Answer 41

SGLT2 inhibitors (glifozins and invokana)

Question 42

How does the tubular fluid conc of Na+ and H2O change as it goes through the proximal tubule?

Answer 42

does not change (isotonic)

Question 43

How does the tubular fluid conc of glucose, amino acids, and HCO3- change as it goes through the proximal tubule?

Answer 43

decreases (reabsorbed into plasma)

Question 44

How does the tubular fluid conc of Cl-, urea, and creatinine change as it goes through the proximal tubule?

Answer 44

increases

Question 45

What percent of the filtrate is reabsorbed at the end of the proximal tubule?

Answer 45

70%

Question 46

What are the features of the thin descending limb of the loop of henle?

Answer 46

- high H2O permeability - NO active solute transport - urea secretion via facilitated diffusion

Question 47

What are the features of the thin ascending limb of the loop of henle?

Answer 47

- does not reabsorb anythign really - impermeable to water - urea secretion via facilitated diffusion

Question 48

What are the features of the thick ascending limb of the loop of henle?

Answer 48

- impermeable to water and urea - major site of Na+, K+, Cl- reabsorption - H+ secretion - forms a hyposmotic solution - distal end forms the JG apparatus

Question 49

By the end of the loop of henle what type of solution is formed?

Answer 49

hyposmotic

Question 50

Where is the major site of Na+, K+, and Cl- reabsorption at?

Answer 50

thick ascending limb

Question 51

Since the thick ascending limb is impermeable to H2O what happens to the luminal osmolarity when solutes are reabsorbed?

Answer 51

osmolarity decreases

Question 52

What percent of the filtrate is reabsorbed by the end of the loop of henle?

Answer 52

20%

Question 53

What is the main functions of the early distal tubule?

Answer 53

- absorbs solute without water - impermeable to water and urea - reabsorbs Na and Cl - further dilutes the filtrate

Question 54

What are the two cell types in the late distal/cortical collecting duct?

Answer 54

- principal cells - intercalated cells

Question 55

What is the function of the principal cells in the late distal/cortical collecting duct?

Answer 55

- aldosterone and ADH action - reabsorb Na+ and water - secrete K+ - impermeable to urea

Question 56

What is the function of the alpha intercalated cells in the late distal/cortical collecting duct?

Answer 56

- important in acidosis - secrete H+ - reabsorb K+ and HCO3- - primary active transport of H+ across apical membrane

Question 57

What is the function of the beta intercalated cells in the late distal/cortical collecting duct?

Answer 57

- important in alkalosis - secrete K+ and HCO3- - reabsorb H+

Question 58

What is the function of hte medullary collecting duct?

Answer 58

- processes a small amount of Na+ and water (but important for regulation) - aldosterone and ADH action - urea reabsorbed via faciliated diffusion - secretes H+

Question 59

What percent of the filtrate is reabsorbed by the end of the collecting duct (final urine)?

Answer 59

9%