KidneyObjective:
Nephron Anatomy and Function
Nephron Anatomyconsists of
Renal corpuscle Renal tubule
Renal corpuscle1. Glomerulus2. Bowman’s
capsule
Bowman’s capsule
Glomerulus
Renal tubule1. Proximal
convolutedtubule(PCT)
Proximal Convoluted
(twisted)
tubule
Renal tubule2. Loop of Henle
Loop of Henle
Renal tubule3. Distal
convolutedtubule(DCT)
Distal Convoluted
tubule
Collecting tubule
Collecting tubule
Nephron Function
Three Processes - 1. Filtration
(blood to capsule)2. Reabsorption
(return to blood)3. Secretion
(added to urine)
1. Filtration
In Renal corpuscle Glomerulus → Bowman’s
capsule Filters from blood
180 liters/day(45 gallons)
[barrel is 55 gallons]
Filtration (cont) To Bowman’s capsule:
Water Amino acids Glucose Urea Na, K, Cl Hormones Vitamins
Filtration (cont) What doesn’t cross
Blood cells Medium to Large proteins
2. ReabsorptionPeritubular capillaries →
PCT, DCT, & Loop of Henle
• Most of water• Glucose• Na K Cl• Amino acids• Vit &
Hormones
PCT
Loop of Henle
3. SecretionPeritubular capillaries →PCT and DCT • Urea• H+ (pH) • Toxins
– Drugs– Antibiotics
Secretion (cont)Peritubular capillaries →Collecting tubules
Collecting tubules
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)
Ureter Connects kidney to bladder 10-12 inches long Made of smooth muscle Uses peristalsis
Rhythmic contractions of muscle
Bladder hollow, muscular Capacity:
700-800 mL (average) Made of:
Transitional epithelium Stretchy!
Smooth muscle
Sphincters
Internal Smooth muscle Autonomic (Automatic) Controlled by spinal cord
Sphincters
External Skeletal muscle Cerebral control Micturition
Expel urine from bladder