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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