The nephron is the functional unit of the kidney, composed of the renal corpuscle (glomerulus and Bowman's capsule) and renal tubule (proximal convoluted tubule, loop of Henle, and distal convoluted tubule). Key functions include filtration, reabsorption, and secretion, with approximately 180 liters of blood filtered daily, 179 liters reabsorbed, and 1 liter excreted as urine. The ureters connect kidneys to the bladder, which stores urine, while sphincters help control urination.

1. Nephron
Anatomy
consists of
Renal corpuscle
Renal tubule

2. Renal corpuscle
1. Glomerulus
2. Bowman’s
capsule
Bowman’s
capsule
Glomerulus

3. Renal tubule
1. Proximal
convoluted
tubule
(PCT)
Proximal
Convoluted
(twisted)
tubule

4. Renal tubule
2. Loop of Henle
Loop of
Henle

5. Renal tubule
3. Distal
convoluted
tubule
(DCT)
Distal
Convoluted
tubule

6. Collecting
tubule
Collecting
tubule

7. Nephron Function
Three Processes -
1. Filtration
(blood to capsule)
2. Reabsorption
(return to blood)
3. Secretion
(added to urine)

8. 1. Filtration
In Renal corpuscle
 Glomerulus → Bowman’s
capsule
 Filters from blood
180 liters/day
(45 gallons)
[barrel is 55 gallons]

9. Filtration (cont)
 To Bowman’s capsule:
 Water
 Amino acids
 Glucose
 Urea
 Na, K, Cl
 Hormones
 Vitamins

10. Filtration (cont)
 What doesn’t cross
 Blood cells
 Medium to Large
proteins

11. 2. Reabsorption
Peritubular capillaries →
PCT, DCT, &
Loop of Henle
• Most of water
• Glucose
• Na K Cl
• Amino acids
• Vit &
Hormones
PCT
Loop of
Henle

12. 3. Secretion
Peritubular capillaries →
PCT and DCT
• Urea
• H+ (pH)
• Toxins
– Drugs
– Antibiotics

13. Secretion (cont)
Peritubular capillaries →
Collecting tubules
Collecting
tubules

14. Daily Totals
 Filtration ~ 180 liters
filtered out/day
 Reabsorption ~ 179
liters returned to the
blood/day
 ~ 1 liter excreted as
urine/day
(0.78 mL/min)

15. Ureter
 Connects kidney to
bladder
 10-12 inches long
 Made of smooth muscle
 Uses peristalsis
 Rhythmic contractions of
muscle

16. Bladder
 hollow, muscular
 Capacity:
 700-800 mL (average)
 Made of:
 Transitional epithelium
 Stretchy!
 Smooth muscle

17. Sphincters
 Internal
 Smooth muscle
 Autonomic
(Automatic)
 Controlled by spinal
cord

18. Sphincters
 External
 Skeletal muscle
 Cerebral control
 Micturition
 Expel urine from
bladder