Urinary System

Kidney Embryology

• Pronephros
• Mesonephros
• Metanephros
  • Metanephric blastema
  • Metanephric diverticulum

Metanephric Blastema

• Glomerulus
• Renal tubules

Metanephric Diverticulum

• Collecting ducts
• Renal calyces
• Renal pelvis
• Ureter

Urinary Tract Embryology

Primordial	Female	Male
Urogenital sinus	Urinary bladder	Urinary bladder
	Proximal 1/3 urethra	Prostatic urethra
	Middle 1/3 urethra	Membranous urethra
Urogenital fold	Distal 1/3 urethra	Penile urethra

Hormones Acting on Kidney

Hormone	Locations	Effect
ANP	Arterioles	Vasodilation
Catecholamine	Arterioles	Vasoconstriction
Prostaglandin	Afferent arteriole	Vasodilation
Angiotensin	Efferent arteriole	Vasoconstriction
Angiotensin	Proximal convoluted tubule	Na reabsorption
Aldosterone	Collecting tubule	Na reabsorption
ADH	Collecting tubule	Water reabsorption
Parathyroid hormone	Proximal convoluted tubule	Phosphate secretion
Parathyroid hormone	Distal convoluted tubule	Ca reabsorption

Relative Concentrations Along Proximal Convoluted Tubules

Ion Channels of the Kidney

Loop of Henle

Distal Convoluted Tubule (DCT)

Filtration Fraction (FF)

Parameter	FF = GFR ÷ RPF
GFR	Glomerular filtration rate (mL/min)
RPF	Renal plasma flow (mL/min)

Fractional Excretion (FE)

Parameter	(UX ÷ UCr) ÷ (PX ÷ PCr)
UX	Urine X
UCr	Urine creatinine
PX	Serum X
PCr	Serum creatinine

Trans-tubular Potassium Gradient (TTKG)

Parameter	(UK ÷ UOsmolality) ÷ (PK ÷ POsmolality)
UX	Urine potassium (mEq/L)
UOsmolality	Urine osmolality
PX	Serum potassium (mEq/L)
POsmolality	Serum osmolality

Cockcroft-Gault Equation of Creatinine Clearance

Parameter	(140 – Age) × W ÷ (72 × Cr) × 0.85 (if female)
Age	Age (year)
W	Weight (kg)
Cr	Serum creatinine (mg/dL)

MDRD Equation of Glomerular Filtration Rate (GFR)

Parameter	186 × Cr-1.154 × Age-0.203 × 1.212 (if black) × 0.742 (if female)
Age	Age (year)
Cr	Serum creatinine (mg/dL)