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The Excretory System Excretory System Facts! • As cells perform the chemical activities that keep you alive, waste products such as carbon dioxide and ammonia are formed. • To maintain homeostasis and keep you healthy, they must be removed. Functions of Excretory System • Rids blood of wastes like urea, ammonia, and carbon dioxide. • Controls blood volume by removing extra water produced by cells. • Balances salts and water so cells can function properly. Excretory System • Organs – – – – – – kidneys ureters urinary bladder urethra lungs skin lungs sweat glands Organs of Excretion There are other organs in our body that can excrete substances • lungs – carbon dioxide and water vapor are exhaled • skin – excess salt is released when you sweat. Organs of the Excretory System • kidneys –filters blood and eliminates cellular waste. Returns salt, ions and glucose to the blood. Organs of the Excretory System Organs of the Excretory System • ureters – two narrow tubes that urine flows through to get to the bladder. Organs of the Excretory System • urinary bladder – sac-like muscular organ that stores urine. Organs of the Excretory System • urethra – tube that urine travels to leave the body. The Filtering Process • Your cells have to maintain a certain level of water and salt to function properly. Vocabulary Word! • nephrons – tiny structures that filter blood in the kidneys. Filtering Out Waste • After entering the kidneys, blood flows through smaller and smaller arteries. • The blood eventually reaches a cluster of capillaries called nephrons. • In the nephron, urea, glucose, other chemicals, and some water move out of the blood and into the nephron. Filtering Out Waste • Blood cells and proteins stay in the capillaries. • Glucose, water, and small amounts of other substances are reabsorbed into the blood stream. • Urea and other wastes stay in the nephrons. Filtering Out Waste • The liquid left in the tube is urine. • The urine moves down the ureters and into the bladder. • When the bladder is full, you feel the urge to urinate. Filtering Summary • 1. both wastes and needed materials are filtered out of the blood • 2. the needed material is returned to the blood • 3. the waste is eliminated in the urine Analyzing Urine • Some medical problems can be found by testing urine • Glucose – diabetes • Protein – kidney failure • Drug residue – drug abuse Body systems that work with the excretory system; • circulatory system to carry waste to the kidneys. • respiratory system to remove carbon dioxide. • integumentary system to remove salt. Comparing Cells to Body What cell organelle helps to break down waste? lysosomes What cell organelle packages waste? golgi body