10.1 Urinary System Anatomy

Notes

The urinary system removes metabolic wastes (urea, creatinine, uric acid), regulates water, electrolytes and pH, controls blood pressure and makes hormones (EPO, renin).

• Organs: two kidneys (retroperitoneal, at the back), two ureters (carry urine to the bladder by peristalsis), the urinary bladder (stores urine, smooth detrusor muscle), and the urethra (carries urine out).
• The kidney has an outer cortex, inner medulla with renal pyramids, and a renal pelvis that collects urine. The renal artery brings blood in and the renal vein takes it out.
• The nephron is the functional unit (about 1 million per kidney).
• Female urethra is short (about 4 cm), so women get urinary tract infections more often. Male urethra is about 20 cm and also carries semen.
• Normal urine is about 95% water, with urea and salts, and it is yellow from urochrome.