distal tubule & collecting duct

Question 1

Where does the distal tubule start and end?

Answer 1

Between macula densa and the cortical collecting duct (where other distal tubules join to empty into it)

Question 2

What are the overall functions of the distal tubule and collecting ducts? (Select all that apply)

• NaCl & water reabsorption
• Short term regulation of Na excretion
• H+ ion secretion
• K+ reabsorption

Answer 2

• NaCl & water reabsorption
• Short term regulation of Na excretion
• H+ ion secretion

Question 3

What is the main function of the early dt/distal convoluted tubule vs the late dt/connecting tubule?

Answer 3

Early dt = NaCl reabsorption

Late dt = NaCl & H₂O reabsorptoin

Question 4

What cells make up the early dt vs the late dt?

Answer 4

• Early distal tubule
  
  • Distal convoluted cell - NaCl reabsorption
• Late distal tubule
  
  • Connecting tubule cell (75%)
    
    • NaCl & H₂O reabsorption
    • K+ secretion
  • Intercalated cell (25%)
    
    • H+ secretion

Question 5

What are the 3 segments of collecting duct? What proportions are their principal to intercalated cell?

Answer 5

• Cortical cd
  
  • 75p:25i
• Outer medullary cd
  
  • 80p:20i
• Inner medullary cd
  
  • 99p:1i

Question 6

Function of principal cell vs intercalated cells

Answer 6

Principal cells: NaCl & H2O reabsorption; K+ secretion. _{(just like connecting tubule cell)}

Intercalated cell: H+ secretion