1. Excretion of Waste
The Urinary System

2. Human Urinary Tract
Human urinary tract diagram

3. The Kidney’s job: Urea (nitrogen waste from proteins) Excess Salts
Filtration and removal of metabolic wastes from the blood
Urea (nitrogen waste from proteins)
Excess Salts
Excess Water
Excess Glucose (sugar)
Excess Minerals (Na+, K+, Ca2+)

4. Function of the Kidney- filtration, secretion, reabsorption, excretion
kidney animation

5. Nephron- the functional unit of the kidney. Each kidney has about 1
Nephron- the functional unit of the kidney. Each kidney has about 1.3 million of these little filtration units! Magnified, they look like this:

6. Formation of Urine:
Filtration: materials from the blood are forced out of the glomerulus into the Bowman’s capsule (“filtrate”).
Reabsorption: some of the substances that left the blood need to be returned, for homeostasis purposes, and so are selectively diffused or actively transported out of the proximal convoluted tubule back into the capillaries
Secretion: final “tweak”. Some more wastes and H+ ions are secreted from the blood into the distal convoluted tubule

7. Human Urinary Tract
Human urinary tract diagram