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