EXCRETION

- is the process of removing metabolic wastes (metabolic means it has entered the body cells)

A. The metabolic activities of living organisms result in the production of waste materials Metabolic ActivityWastes cellular respiration carbon dioxide + water dehydration synthesis water certain metabolic processes mineral salts protein metabolism nitrogenous

1. nitrogenous wastes (come from the breakdown of amino acids) are produced when excess amino acids are utilized in cellular respiration. 2. nitrogenous wastes vary from the extremely toxic ammonia to less toxic urea and the nontoxic uric acid. 3. excretion maintains homeostasis by regulating the chemistry of body fluids and maintaining body temperature.

II. ORGANS of EXCRETION for HUMANS A. Liver- multipurpose organ which include functions of 1) making bile 2) detoxifies blood, 3) destroys red blood cells 4) makes urea from excess amino acids. 1. deamination the amine group (NH2) + an extra Hydrogen are removed from amino acids (a.a. can not be stored in the body) and converted to ammonia which is later converted into urea

2. cirrhosis- inflammation of liver cells & surrounding tissues liver cells don't function properly. 3. gout- also associated with diets containing increase levels of specific organ compounds. 4. jaundice a condition when bile is not excreted properly and metabolic wastes are reabsorbed into the blood; this cause skin to look yellow.

B. Urinary System (organs of urinary system are: kidneys, ureters, urinary bladder, urethra) Kidneys 1. Kidneys have two functions a. remove metabolic wastes from the blood (make urine) b. control the concentration of many substances in body tissue. 2. Ureter carries urine to bladder 3. Urinary Bladder stores urine 4. Urethra carries urine outside the body

C. Lungs - excrete Carbon Dioxide, Water & Heat which are waste products of cell respiration D. Sweat Glands of Skin Water, salts, and some urea diffuse from the blood into the sweat glands and are subsequently excreted as perspiration.

Respiration is only incidentally excretory, its primary function being temperature regulation. Evaporation of the sweat (98% water and 2%salts and urea) occurs when heat is absorbed from skin cells. This absorption of heat lowers body temperature. Temperature regulations an example of homeostasis. Skin has two layers the epidermis and the dermis. The epidermis is the above layer while the dermis is the inner layer.

epidermis: tightly packed epithelial cells. Tough, waterproof; protects the dermis dermis: elastic connective tissue supports skin, binds it to muscles & bones has blood vessels, lymph vessels nerves, sense receptors, glands & hair follicles layer of fat (adipose tissue) below sebaceous glands which secrete oil sweat glands secrete Respiration (urea, water, salt)

Functions of the SKIN 1. Protection 2. Excretion 3. Sensory 4. Temperature Regulation

Why is urine yellow? The liver has many functions. One of them is to breakdown red blood cells. Within the red blood cell is a protein structure called hemoglobin. When hemoglobin breaks down it produces a pigment called urochrome. This yellow pigment is constantly filtered out of the blood as a waste product. Since red blood cells are constantly being destroyed by our liver, urochrome is continually being made. This pigment makes our urine yellow.