The Excretory System
Dec 27, 2015
Excretory System
• 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.
Facts!
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
sweat glands
lungs
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• ureters – two
narrow tubes that urine flows through to get to the bladder.
The Filtering Process• Your cells have to maintain a certain
level of water and salt to function properly.
• nephrons – tiny structures that filter blood in the kidneys.
Vocabulary Word!
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.