III: Tubular Transport II

Question 1

Histology of thin descending and ascending limb membrane

Answer 1

Epithelial membrane without brush border + LOW metabolic activity

Question 2

Histology of thick ascending limb membrane

Answer 2

Thick epithelial membrane + HIGH metabolic activity

Question 3

In pictures, differentiate between thin and thick limb of loop of henle

Answer 3

Thin descending loop of henle looks round with 2/3 round cells

Thick ascending loop of henle looks round with MANY round cells

Question 4

Thin descending limb contains in both membranes

Answer 4

AQP1

Question 5

In thin descending limb what is reabsorbed

Answer 5

High H2O and low solute reabsorption

Question 6

There is an increase osmolarity in

Answer 6

Tubular lumen

Question 7

How much H2O is reabsorbed in the loop of henle

Answer 7

20%

Question 8

Thin ascending limb is permeable/nonpermeable to water

Answer 8

Impermeable

Question 9

Where does reabsorption of Cl- begin

Answer 9

At thin ascending limb

Question 10

Reabsorption of Cl- in ascending limb through

Answer 10

Transcellular pathway (CLC-K1)

Question 11

Na+ reabsorption is through

Answer 11

Paracellular pathway

Question 12

In thick ascending limb, what is reabsorbed

Answer 12

Solutes and not water

Question 13

How much filtered Na+ and Cl- does the THICK ascending limb reabsorb

Answer 13

25%

Question 14

K+, Cl- and Ca++ also reabsorbed in the

Answer 14

Thick ascending limb

Question 15

Descending and ascending limb permeability

Answer 15

Descending is permeable
Ascending is impermeable

Descending reabsorbs water
Ascending reabsorbs solutes

Question 16

What is reabsorbed in thick ascending limb

Answer 16

Na+, K+, Cl-, HCO3-, Mg+

Question 17

Channels involved in Thick ascending limb (reabsorption of Na+, Cl-, K+, Mg++, Ca++, HCO3-)

Answer 17

NHE3 (H+, Na+)
AQP
NKCC2 (Na+, 2Cl-, K+)
ROMK (K+)
Na+/K+ATPase

Direct ones for K+ and Cl-

Question 18

Why is there a decrease in tubular osmolarity in thick ascending limb

Answer 18

Because no H2O is reabsorbed

Question 19

Distal convoluted tubule sections

Answer 19

Initial portion
Distal portion (connecting tubule)

Question 20

Collecting tubule sections

Answer 20

Cortical

Medullary

Question 21

Initial part of distal convoluted tubule called the

Answer 21

Cortical diluting segment

Question 22

Initial part of distal convoluted tubule reabsorbs (Na+, Cl-) %

Answer 22

5%

Question 23

What is not reabsorbed in INITIAL part of distal convoluted tubule

Answer 23

Water or urea

Question 24

If not water or urea is reabsorbed in INITIAL part of distal convoluted tubule then (osmolarity)

Answer 24

Low tubular osmolarity

Question 25

Channels involved in INITIAL portion of distal convoluted tubule

Answer 25

NCC (Cl-, Na+) Na+/K+ATPase Paracellular transport of Ca++, Mg++, Na+, Ka+ Transcellular transport of Cl- and K+

Question 26

There is paracellular transport of

Answer 26

Mg++, Ca++,

Question 27

There is transcellular transport of

Answer 27

Cl-

Question 28

Location of connecting tubules (cortex and medulla)

Answer 28

Begin at cortex but most are at medulla

Question 29

Cells involved in connecting tubules

Answer 29

ADH | Aldosterone

Question 30

Function of ADH

Answer 30

Reabsorb water

Question 31

Function of aldosterone

Answer 31

Reabsorb Na+ and secrete K+

Question 32

Intercalated cells at CONNECTING TUBULES function

Answer 32

Regulate acid-base balance

Question 33

H+ secretion in intercalated cells. Which cells does this

Answer 33

Type A cells

Question 34

HCO3- secretion in intercalated cells. Which cell does this?

Answer 34

Type B cell

Question 35

How much Na+ is reabsorbed in distal tubule + collecting tubules

Answer 35

3%

Question 36

Why is there only a 3% reabsorbtion of Na+ in distal tubule and collecting ducts

Answer 36

Because it is hormone regulated

Question 37

Inhibitor channels

Answer 37

Amiloride triamterene | Sironolactone

Question 38

Inhibition of amiloride triamterene

Answer 38

Blocks Ca++ channels | Inhibit ENaC therefore inhibit aldosterone induced increase in Na+ reabsorption

Question 39

Which channel is blocked through amiloride triamterene

Answer 39

ENaC

Question 40

Inhibition of Spironolactone

Answer 40

Aldosterone antagonist. Prevents aldosterone from entering nucleus = blocks mRNA synthesis

Question 41

Aquaporins depend on...

Answer 41

ADH

Question 42

Why do aquaporins depend on ADH

Answer 42

Because ADH stimulates water absorption

Question 43

What would happen if there was no ADH

Answer 43

There will be no water permeability

Question 44

ADH causes

Answer 44

Increased osmolarity ADH release Water permeability

Question 45

In diabetes insipidus there is no

Answer 45

ADH

Question 46

In SIADH there is

Answer 46

High ASDH

Question 47

Intercalated cells regulate

Answer 47

Acid-base homeostasis

Question 48

Type A cells in intercalated cells in charge of

Answer 48

Acidosis Secrete H+ Reabsorb HCO3- Reabsorb K+

Question 49

Type B cells in intercalated cells in charge of

Answer 49

Alkalosis Secrete HCO3- Secrete K+ Reabsorb H+

Question 50

Collecting tubule at medullary segment, H2O reabsorption

Answer 50

Adjusted due to permeability controlled by ADH

Question 51

Collecting tubule at medullary segment permeability to urea

Answer 51

Permeable

Question 52

What does the collecting tubule at medullary segment secrete

Answer 52

H+

Question 53

What % of Na+ is finally reabsorbed in collecting tubule of medullary segment

Answer 53

<1%Na+