CC - Reabsorption and Secretion

Question 1

What is reabsorption?

Answer 1

The movement of filtered solutes and water from the lumen of the tubule back to the plasma

Question 2

What volume of filtrate is actualy excreted into urine?

Answer 2

1.5L out of 180L filtrate

Question 3

What structures in the nephron are present in the medulla and in the cortex?

Answer 3

Cortex

• Arterioles
• Glomerulus
• Bowman’s capsule
• PCT
• DCT

Medulla

• Loop of Henle
• Collecting duct

Question 4

What are some structural properties of the PCT and DCT?

Answer 4

PCT

• Thick brush border (cilia)
• Many mitochondria
• Indistinct lateral borders

DCT

• Modes microvillous border
• Mitochondria at the base

Question 5

How is a substance reabsorbed? (3)

Answer 5

1. Transported across the tubular epithelial membranes
2. Into the renal interstitial fluid
3. Travels through the peritubular capillary membrane back into the blood

Question 6

What are 2 ways to increase osmolarity of the interstitium?

Answer 6

1) Sodium across the epithelium

• Sodium transporters located in various segements of the nephron

2) Sodium-linked glucose reabsorption

• Glucose is actively transported across the apical membrane by sodium-linked active transport

Question 7

Where is urea secreted and reabsorbed?

Answer 7

Secreted

• Into the Thin ascending limb of the L.O.H (reach the DCT)

Reabsorbed

• In the PCT with water
• In the collecting ducts with water

Question 8

What is secretion?

Answer 8

The transfer of molecules from the ECF into the lumen of the nephron

• Drugs are eliminated by secretion

Question 9

What is excretion?

Answer 9

Urine ouput is a result of all processes that occur in the kidney

Question 10

What formula allows for the calculation of amount of solute excreted?

Answer 10

Amount of solute excreted =
amount filtered + amount secreted