Renal Function Secretion + Absorption

Question 1

Where does secretion and reabsorption occur in the nephron
-where the most and where the least?

Answer 1

-most in PCT & DCT
-limited amount in LOH

Question 2

Reabsorption occuring is…

Answer 2

Selective, cell specific, energy dependent

Question 3

Is reabsorption in PCT regulated or not? What is commonly reabsorbed at this location?

Is reabsorption in DCT, CD regulated or not? What is commonly reabsorbed at this location?

Answer 3

1. Unregulated, mostly; glucose, AAs, water
2. Regulated, mostly water & ions

Question 4

Describe features of reabsorption at the PCT
-permeability
-substances lost or reabsorbed?
-osmotic level

Answer 4

Highly permeable
Many different solutes apart from K+
Isosmotic; as solutes get reabsorbed, water is reabsorbed with them

Question 5

Describe features of reabsorption at the LOH descending loop (DL) and thick ascending loop (TAL)
-permeability
-substances lost or reabsorbed?
-osmotic level

Answer 5

• At DL;
  -Water-permeable
  -as loop of henle moves down and drops into medulla it becomes hyperosmotic as lots of water is pulled out and lost (only water leaves)
• At TAL;
  -active reabsorption occuring
  -becomes impermeable to water
  -solutes lost but water retained
  -osmolarity dropped so filtrate back to being isosmotic at entry to DCT

Question 6

Describe features of reabsorption at the DCT
-permeability
-substances lost or reabsorbed?
-osmotic level

Answer 6

-Low permeability- water is retained
-glucose and other proteins lost
-ISOSMOTIC or sometimes hypoosmotic

Question 7

Describe features of reabsorption at the DCT
-permeability
-substances lost or reabsorbed?
-osmotic level

Answer 7

-low permeability
-water reabsorbed
-hyperosmotic

Question 8

Product of filtration sits in _______ of tubule

Answer 8

Lumen

Question 9

Why is reabsorption favoured over secretion in the peritubular capillaries

Answer 9

Due to lots of water having been secreted there is High oncotic pressure and low hydrostatic pressure which so water absorption if favoured

Question 10

What are the 2 types of pathways through which reabsorption can occur

Answer 10

1. Paracellular Pathway—>
   substance moves between cells via tight junctions called Zona occludes and Claudius within them
2. Transcellular Pathway—>
   substance moves through cell

Question 11

If substance doesn’t get reabsorbed, what happens to it

Answer 11

It is excreted

Question 12

Describe process of transcellular pathway reabsorption within nephron

Answer 12

On goodnotes*

Question 13

Unlike other places in body, where is the Na+K+ATPase pump present in the tubular cells?
Na+ transport always from _______ to __________

Answer 13

Basolateral membrane
Lumen it capillaries