Renal Tubules

Front 1

Proximal Tubule 3 general symports with Na

Back 1

1. Glucose
2. Amino Acids
3. Phosphate

Front 2

Proximal Tubule 1 antiport

Back 2

1. H+

Front 3

Proximal Tubule - glucose transport

Back 3

- SGLT2 and SGLT1

Front 4

Proximal Tubule- Amino Acid transport

Back 4

- Neutral
- Dibasic/ cation
- Dicarboxylic/ anion

Front 5

Proximal Tubule- Phosphate transport

Back 5

- NPT2A (NPT2C)

Front 6

What affects/decreases reabsorption of PO4 in proximal tubule?

Back 6

- PTH

Front 7

Proximal tubule has passive reabsorption of what 6 chemicals?

Back 7

- urea
- uric acid
- K
- Ca
- Mg
- Cl (also active with anion)

Front 8

Protein in proximal tubule

Back 8

- reabsorbed via megalin/cubulin in clatherin pits

Front 9

What is secreted in proximal tubule?

Back 9

- Organic cations and organic anions

Front 10

Mechanism for cation/anion transport in proximal tubule?

Back 10

- plasma to cell via OCT
- Cell to urine via OC/H+ antiport

Front 11

Water transport in proximal tubule?

Back 11

- AQ-1

Front 12

What is purpose and mechanism of NHE-3's H+ secretion

Back 12

- Bicarbonate reclamation
- Secretion of H+ combines with HCO3-, which then changed to H20+ CO2 and CO2 diffuses into cell, changes back into bicarb and exits into plasma

Front 13

The cubulin/megalin pits serve a purpose besides protein reabsorption in the creation of what molecule? How?

Back 13

- Vit D by hydroxylating it to active form within the mitochondria

Front 14

The thin descending loop of henle is permeable/impermeable to what molecules? (name the transporter)

Back 14

- permeable to water (with Aq-1)
- impermeable to NaCl

Front 15

The altered permeability in the thin descending loop of Henle allows what to happen to the urine at the apex of the loop?

Back 15

- become more concentrated

Front 16

The thin/thick ascending loop of henle is permeable/impermeable to what molecules? (name the transporter)

Back 16

-permeable to NaCl (NKCC2- Na, K, 2 Cl)
- impermeable to water

Front 17

The altered permeability in the thin/thick ascending loop of henle allows what to happen to the urine?

Back 17

- become more dilute

Front 18

What occurs in the thick ascending loop of henle (mTAL) and the thin descending in the single effect?

Back 18

- mTAL- pushes solutes (NKCC2) into interstitium (gradient between mTAL and interstitium) so tubule is hypoosmotic to the interstitium

- Thin descend- pushes water to interstitium, so that the interstitium and thin descending are isoosmotic, but the thin descending is hyperosmotic to the mTAL

Front 19

Describe Countercurrent multiplication

Back 19

- the continuous secretion of water from the thin descending loop and secretion of solutes from the thick ascending loop to keep a 200 gradient between the two
- this also allows the thin descending to have the same osmolality as the interstitium, but is hyperosmotic to the mTAL

Front 20

What is the effect of ADH on the final urine osmolality if ADH is high? (detailed steps)

Back 20

- ADH within plasma binds to V2R
- V2R activates G protein, phosphate kinase to PKA
- PKA acts on a vessicle within the cell that contains AQ-1
- AQ-1 is placed on the apical surface of the cell to increase H2O reabsorption (without Na)

Front 21

If ADH is low what happens to the AQ-1 on the apical surface? Effect on concentration of urine in the tubule?

Back 21

- AQ-1 is endocytosed by a vessicle
- water remains in the tubule so urine is more dilute

Front 22

What are the 2 main receptor types in the first part of the distal convoluted tubule?

Back 22

1. NCC~ Na and Cl into cell
2. TRPM6- Mg into the cell

Front 23

What inhibits NCC?

Back 23

- Thiazide diuretics

Front 24

What is the major and minor transporters in the second part of the distal convoluted tubule?

Back 24

Major- TRPV5- Ca into cell
Minor- NCC- Na/Cl into cell

Front 25

What 2 things affect TRPV5?

Back 25

- PTH and active Vit D increases transcription to increase Ca reabsorption

Front 26

What are the 4 channels in the connecting segment?

Back 26

1. ROMK (K secreted)
2. ENaC (Na enters alone)
3. H-ATPase (H secreted alone)
4. TRPV5 (Ca reabsorbed)

Front 27

What are the 2 main channels in the Cortical CD?

Back 27

1. ENaC (Na enters)
2. ROMK (K secreted)

Front 28

Which diuretic works on the Cortical CD and how?

Back 28

- K-sparing by blocking the uptake of Na via ENaC (reducing bp), prevents the electrochemical barrier from forming so there is no drive for K to leave the cell via ROMK
(amiloride/triameterine)

Front 29

How does aldosterone work?

Back 29

- increases the expression of ENaC
- increases the permeability of ROMK
- increases expression of the Na/K ATPase
(increases bp)

Front 30

What is the main cell types found in the cortical collecting duct?

Back 30

principle cell and intercalated cells

Front 31

What is the purpose and transporter of Type A intercalated cells in OMCD and IMCD?

Back 31

- Secretes acid (H+) via H ATPase
- HCO3- goes to plasma

Front 32

What is the purpose/transporter of Type B intercalated cells in OMCD and IMCD?

Back 32

- Secrete bicarbonate via pendrin
- H+ goes to plasma

Front 33

The terminal segment of the IMCD is comprised of what type of cells?

Back 33

IMCD cells

Front 34

What is the major and 4 minor transporter found in IMCD cells and its purpose?

Back 34

- AS (amiloride sensitive) allows Na to be reabsorbed
- Minor
1. ANP receptors (Na secreted and not reabsorbed via AS)
2. HK- ATPase (K reabsorbed, H secreted)
3. AQ 2, 4 for water reabsorption
4. ADH receptors

Front 35

Which area of the tubule creates the JG cells?

Back 35

- epithelial cells of the afferent arterioles

Front 36

What is the purpose of the JG cells?

Back 36

- release renin when there is a decrease in stretch (decrease in blood pressure)

Front 37

Which area of the tubule creates the macula densa?

Back 37

- epithelium of the early distal convoluted tubule

Front 38

What is the purpose of the macula densa?

Back 38

- detects ion composion/tubular flow rate to send signals to mesangium when bp drops

Front 39

Where are the Lacis/Goormaghtigh cells located?

Back 39

- beneath macula densa, but above the mesangium

Front 40

What is the proposed purpose of the Lacis/ Goormaghtigh cells?

Back 40

- link arterioles and mesangium

Front 41

Microscopic features of the Proximal convoluted tubules

Back 41

- thick brush border
- extensive interdigitations
- high number mitochondria
- irregular nuclei
- no clear borders

Front 42

What is the microscopic differences between the proximal and distal convoluted tubule (according to the dct)

Back 42

- the distal convoluted tubule does not have a thick brush border

Front 43

What are the microscopic features of the collecting duct?

Back 43

- regular nuclei
- recognize individual cells
- sits on bm (no interdigitating cells)
- low number mitochondria

Front 44

Which diuretic acts in the proximal tubule and how?

Back 44

- Carbonic anhydrate inhibitor by decreasing bicarbonate reabsorption