TEAS® Science Study Guide
Urinary System
The urinary system filters waste from the blood, produces urine, and regulates fluid and electrolyte balance.
Path of urine
Kidneys → ureters → bladder → urethra → out of the body
Ureters and urethra are easy to confuse. Ureters (two of them) run from the kidneys to the bladder. The urethra (one) carries urine out.
The kidney
The kidney’s functional unit is the nephron — the microscopic structure that actually does the filtering. Each kidney contains about a million.
Three steps of urine formation
- Filtration — Blood pressure forces water and small molecules out of the blood and into the nephron.
- Reabsorption — Useful substances (water, glucose, ions) are pulled back into the blood.
- Secretion — Additional waste is added to the filtrate. What remains becomes urine.
Healthy urine should contain no glucose and no protein. Glucose in the urine can indicate diabetes; protein can indicate kidney damage.
Beyond waste removal
The kidneys also regulate blood pressure, maintain pH balance, control fluid volume, and trigger red blood cell production. They are homeostasis organs as much as filtration organs.
Terms to know
- Nephron — The functional filtering unit of the kidney.
- Ureter — Kidney to bladder. Urethra — Bladder to outside.
- Filtration — Removing substances from the blood into the nephron.
- Reabsorption — Returning useful substances to the blood.
What the TEAS asks most
- What is the functional unit of the kidney? Nephron.
- Ureter or urethra — which carries urine out of the body? Urethra.
- Should healthy urine contain glucose? No.
- What do the kidneys regulate besides waste? Blood pressure, pH, and fluid balance.