Physiology Review Slides Lec. 17

Question 1

Thin ascending loop of Henle

Answer 1

• Impermeable to Water
• Reabsorbs NaCl
• Tubular Fluid becomes DILUTE
• Urea diffused INTO limb

Question 2

Thick Ascending limb in the Loop of Henle

Answer 2

• Impermeable to water
• Large amounts of Na+, Cl-, K+ and other ions are ACTIVELY transported from Tubule into Medullary Interstitium
• Tubular Fluid becomes DILUTE

Question 3

Early Distal Tubule

Answer 3

• Similar to the THICK Ascending limb of Henle

- Tubular fluid becomes more DILUTE (50mOsm/L)

Question 4

Fxn of Angiotensin II

Answer 4

• Increased Sodium and Water Reabsorption

- Returns Blood Pressure and EC volume towards normal

Question 5

Descending limb in the loop of Henle

Answer 5

• Highly permeable to Water

- LESS permeable to NaCl and Urea

Question 6

Proximal tubule

Answer 6

• Highly metabolic w/ a lot of Mitochondria
• Extensive brush borders
• Reabsorbs 65% of Filtered Electrolytes (Na+, K+, Cl-, HCO3-)
• Reabsorbs ALL filtered glucose
  (90% in the EARLY Prox Tubule) & AA
• Highly permeable to water

Question 7

Late Distal Tubule and CD

Answer 7

• Osmolarity of Fluid Depends on ADH

- Urea is NOT very permeant

Question 8

Where is water reabsorbed to increase urine concentration?

Answer 8

• The Late DISTAL Tubule

- The Collecting Duct

Question 9

Pumps in the THICK Ascending limb

Answer 9

1. Na+/K+ATPase Pump
   - drives reabsorption of K+ INTO cells AGAINST [ ] gradient
2. Na+/K+/Cl- CO-transporter
   - Moves 1 Sodium, 2 Chloride, and 1 potassium INTO the cell

• Slight leak of K+ into the LUMEN

Question 10

T/F: Potassium will find it’s way back to the Lumen

Answer 10

True

Question 11

Effects of Angiotensin II

Answer 11

• Stimulates ALDOSTERONE secretion
• Constricts the EFFERENT Arterioles
• DIRECTLY stimulates Na+ reabsorption in PROXIMAL tubules, Loop of Henle, Distal Tubules, and CD