Lecture 37 - tubule processes

Question 1

What are the roles that occur in each part of the renal tubule ?

• Proximal tubule
• Loop of Henle
• Distil tubule
• Collecting duct

Answer 1

Proximal tubule = bulk reabsorption
Loop of Henle = absorption/creates HOMG
Distil tubule = fine-tuning of electrolytes
Collecting duct = fine-tuning water reabsorption

Question 2

What are some examples of solutes which are reabsorbed (NOT secreted) by the renal tubules ?

Answer 2

= Glucose, water, Na+, Cl-, PO4, Ca2+

Question 3

What are some example of solutes which are secreted (NOT reabsorbed) by the renal tubules?

Answer 3

= Organic cations; monoamines(e.g dopamine, histamine) and drugs (e.g morphine)
= Organic acids

Question 4

What are some examples of solutes which are secreted and reabsorbed by the renal tubules?

• Regulated
• Unregulated

Answer 4

= K+, NH3, H+, HCO3 - regulated

= Urea - not regulated

Question 5

How is water reabsorbed in the collecting duct?

Answer 5

Water is reabsorbed from collecting duct lumen down the osmotic gradient
- hypersomotic medullary gradient is established by the loop of henle which accumulates salts and urea in medulla of kidney

Question 6

What are the processes that occur in the loop of hence?

Answer 6

Descending limb removes water from filtrate
Ascending limb removes NaCl from filtrate
- establishes a hyperosmotic medullary gradient - through the accumulation of salt and urea in the kidney