1. Homeostasis – “keeping things in balance”
The Excretory System
The function of the excretory system is to eliminate waste products from the body in ways that maintain homeostasis.
Homeostasis – “keeping things in balance”
The excretory system includes skin, lungs, liver, large intestines, kidneys, ureters, urinary bladder, urethra.

2. The ureters carry urine from the kidney to the bladder.
The kidneys remove urea, excess water and other waste products from the blood and passes them to the ureter. This fluid is urine.
Kidney
Kidney
Urea –is a toxic compound that is produced when amino acids are used for energy.
Ureter
Ureter
The ureters carry urine from the kidney to the bladder.
The bladder is a saclike organ where urine is stored until it is excreted.
The urethra carries urine from the bladder and releases it from the body.
Bladder
Urethra

3. Inside the Kidneys
Blood with waste products enters the kidney through the renal artery.
The nephrons in the kidneys filter the blood.
Clean blood is sent back out - or reabsorbed - into renal vein and returns to circulation in the blood system.
The waste (urine) is sent through the ureter to the bladder.
Illustration copyright 2000 by Nucleus Communications, Inc.

4. More on the Kidneys
The kidneys filter all the blood in the body approximately every 45 minutes.
When blood is filtered through the kidneys, small molecules, including salts, amino acids, sugars and many drugs are removed from the blood. Although many are reabsorbed into the blood, drugs generally remain in the filtrate and are eliminated in the urine. This is how drugs (legal and illegal) become concentrated in the urine.

5. Of the different body systems we have studied . . . .
Can you name the ways that your body removes wastes??
What role does the circulatory system play in waste removal?