JH-KEADLE The Excretory System

procedure 1. Mix a teaspoon of dirt and 150 mL of water in a beaker. Stir the mixture until most of the dirt is dissolved. 2. Add food coloring to the beaker. 3. Stir the mixture until all is mixed. 4. Layer a coffee filter over the neck of a second beaker and secure with a rubber band. Do not pull filters tightly across the top. Allow them to dip a little.

procedure 5. Pour the dirt and water mixture onto the filter paper. Pour slowly and carefully so as not to overflow the filter. 6. In your spiral, describe what is happening in the demonstration.

The nephron Using the laptops, look up an image of a nephron. Draw a picture of the nephron in your spiral.

Excretory System Why do our bodies need to filter waste from the body? Maintain homeostasis Removal of harmful materials Removal of excess fluids, chemicals, minerals, vitamins, salts, and other wastes from the blood

Excretory System Organs kidneys ureters urinary bladder urethra lungs skin

Organs of the Excretory System sweat glands lungs

Functions of Excretory System Rids blood of wastes (urea) Controls blood volume by removing extra water produced by cells Balances salts and water so cells can function properly http://commons.wikimedia.org/wiki/File:Illu_urinary_system.jpg

Organs of the Excretory System kidneys – major organs of the excretory system that filters blood and eliminates urea, excess water, and other wastes

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

Other Organs of Excretion There are other organs in our body that can excrete substances Lungs – carbon dioxide and water Skin – sweat, water, some chemicals Liver – breaks down molecules, recycles hemoglobin and turns it into bile

The Filtering Process Every drop of blood in your body passes through the kidneys and is filtered 300 times a day 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

Which is not a function of the excretory system? Removes wastes from the blood Removes excess water from the blood Removes carbon dioxide from the blood Removes excess salt from the blood

Which system does not include an excretory organ? Excretory system Integumentary system Cardiovascular system Respiratory system

Where is urine stored until the body is ready to eliminate it? Kidneys Ureters Bladder Urethra

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