EXCRETORY SYSTEM

Excretion Excretion: the process by which metabolic wastes and excess substances are removed from an organism

Major Metabolic Waste Products 1. Carbon dioxide formed during celllular respiration

2.Water formed during cellular respiration also formed during dehydration synthesis 2.Water formed during cellular respiration also formed during dehydration synthesis

3. Nitrogenous wastes - ammonia - urea - uric acid: comes from the breakdown of amino acids

4.Mineral salts by-product of metabolic reactions 4.Mineral salts by-product of metabolic reactions

Gotta Get Rid of Them!  In high concentrations, these waste products are poisonous to an organism  To maintain homeostasis an organism must get rid of these waste products IIn high concentrations, these waste products are poisonous to an organism TTo maintain homeostasis an organism must get rid of these waste products

Excretion in Protists  In unicellular organisms, wastes diffuse out of the cell through the cell membrane and into the surrounding water

In ameba and paramecium water constantly enters the cell by osmosis Excess water is pumped out by a contractile vacuole Water is pumped out against the concentration gradient Homeostasis is maintained In ameba and paramecium water constantly enters the cell by osmosis Excess water is pumped out by a contractile vacuole Water is pumped out against the concentration gradient Homeostasis is maintained

Organs of Excretion 1. Lungs exhale carbon dioxide and water which are waste products 1. Lungs exhale carbon dioxide and water which are waste products

2. Liver Detoxification: remove certain bacteria, drugs, and hormones from blood, and change them into less poisonous forms. - Excess amino acids are broken down and converted to urea 2. Liver Detoxification: remove certain bacteria, drugs, and hormones from blood, and change them into less poisonous forms. - Excess amino acids are broken down and converted to urea

3. Kidneys Remove wastes of cellular metabolism from the blood (urea, mineral salts) Regulate concentration of substances including water in the blood 3. Kidneys Remove wastes of cellular metabolism from the blood (urea, mineral salts) Regulate concentration of substances including water in the blood

ZSkin -Excretes small amounts of urea and salt in sweat -Removes excess heat from the body through sweating and blood vessels opening wider

Urinary System 8. Kidneys - 3. Cortex: outer part - 4. Medulla: middle part - 5. Pelvis: inner part ***Nephron: the filtering unit of the kidney, 1.25 million in each kidney 8. Kidneys - 3. Cortex: outer part - 4. Medulla: middle part - 5. Pelvis: inner part ***Nephron: the filtering unit of the kidney, 1.25 million in each kidney

9.Ureter Tube from kidney to bladder which carries urine from the kidneys to the bladder

10. Bladder - Stores urine

11.Urethra Opening from bladder to outside of body. 11.Urethra Opening from bladder to outside of body.

Urine Formation 2 Stages 1. Filtration: both useful substances and wastes are removed from blood 2. Reabsorption: returns important substances to the blood