Distal convoluted tubule and the collecting duct

Question 1

What is the purpose of these areas?

Answer 1

• balance the water needs of the body
• areas where the permablility of the walls of the tubules varies with levels of ADH

Question 2

What are the adaptations of the cells lining the distal convoluted tube?

Answer 2

• many mitochondria to carry AT

Question 3

What happens in the distal convoluted tube if the body lacks salt?

Answer 3

• sodium ions will be actively pumped out the distal convoluted tubule
  
  • chloride ions following down an electrochemical gradient

Question 4

When can water leave the distal tubule?

Answer 4

if the walls of the tubule are permable in response to ADH

Question 5

Where does the collecting duct pass down?

Answer 5

the conc tissue fluid of the renal medulla

Question 6

What is the purpose of the site of the colecting duct?

Answer 6

where the conc and volume of the urine produce is determined

Question 7

What happens to water as it moves down the collecting duct?

Answer 7

moves out by diffusion down a conc gradient as it passes through the renal medulla

urine become more concentrated

Question 8

What happens to the conc of the sodium ions in the surrouding fluid through the medulla from the cortex to the pelvis?

Answer 8

increases

this means water can be removed from the collecting duct all the way along its length

producing a very hypertonic urine when the body needs to conserve water

Question 9

How is the permeablity of the collecting duct controlled?

Answer 9

• level of ADH
• determines how much or little water is reabsorbed

Question 10

Why do some animals have long loop of Henles and some have none at all?

Answer 10

• desert animals have lots of nephrons and very long loops of Henle that travel deep into the medulla
• fish have no loop of Henle and cannot propduce urine that is more conc than their blood