Excretion: removal of cellular wastes

(Carbon dioxide, water, salt, nitrogenous wastes)

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

Excretion in lower organisms – unicellular

- diffusion across the cell membrane

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

2. Ureters: (transports urine)

- connects kidneys to urinary bladder

3. Urinary Bladder:

- stores urine

4. Urethra: (eliminates urine)

- carries urine from the bladder to the outside

Other Organs for excretion:

1. Lungs: excrete carbon dioxide and water from respiration

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

3. Skin

- sweat – perspiration (water, salts, urea)

- controls body temperature

Malfunctions:

1. Gout:

- uric acid deposits in the joints

Kidney Stones:

- high level of uric acid build-up which crystalizes forming stones