2. Excretion: removal of cellular wastes (Carbon dioxide, water, salt, nitrogenous wastes)

3.  Respiration  Dehydration Synthesis  Protein Metabolism  Other Activities  Carbon Dioxide & Water  Water  Nitrogenous Wastes  Mineral Salts Nitrogenous Wastes include: (produced from Deamination) - deamination occurs in the liver – the breakdown of proteins Ammonia – most toxic Urea – less toxic Uric Acid – non-toxic

4. Excretion in lower organisms – unicellular - diffusion across the cell membrane

5. Excretion in Humans: Wastes: Carbon Dioxide, water, salts, urea, uric acid A.Urinary System: 1. Kidney: (2) (produces urine) - filters the blood to make urine - functional unit – nephron (1.25 million in each kidney) - urine – water, salt, urea, uric acid

7. 2. Ureters: (transports urine) - connects kidneys to urinary bladder

8. 3. Urinary Bladder: - stores urine 4. Urethra: (eliminates urine) - carries urine from the bladder to the outside

10. Other Organs for excretion: 1. Lungs: excrete carbon dioxide and water from respiration

11. 2. Liver: - urea – humans main nitrogenous waste – made in liver – removed by the kidneys - break down of red blood cells - deamination – produce urea from protein metabolism

12. 3. Skin - sweat – perspiration (water, salts, urea) - controls body temperature

14. Malfunctions: 1. Gout: - uric acid deposits in the joints

15. Kidney Stones: - high level of uric acid build-up which crystalizes forming stones