The Excretory System
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The excretory system removes wastes
from the body.
nephrons
ureters
urethra
cystitis
urethritis
hemodialysis
How Excretion Works
The excretory system uses several organs to
remove all types of wastes from the body.
The body produces wastes in the form of solids,
liquids, and gases that must be removed so that
the body can function well.
The Lungs, Skin, and Large Intestine
The large surface
area of your skin
allows you to
excrete water and
salts when you
sweat.
The Lungs, Skin, and Large Intestine
The lungs expel carbon dioxide when you
exhale.
Sweating is a form of excretion that helps to
regulate body temperature.
Solid wastes are eliminated through the large
intestine.
The Liver
The liver is the first organ to receive chemicals
absorbed from the small intestine.
The liver detoxifies the body by processing and
excreting into bile toxins such as drugs, alcohol,
and some cellular waste products.
The Urinary System
Kidneys
The Parts of
the Urinary
System
Bladder
Ureters
Urethra
The Urinary System
The main function of the urinary system is to filter
waste and extra fluid from the blood.
Urine is liquid waste material excreted from the
body. It consists of water and body wastes that
contain nitrogen.
The Kidneys
The kidneys remove waste products from the blood
through tiny filtering units called nephrons.
Nephrons
The functional units of
the kidneys
The Kidneys
The kidneys adjust the amount of salts, water, and
other materials excreted according to the body’s
needs.
In this way, the kidneys monitor and maintain the
body’s acid-base and water balances.
The Kidneys
The kidneys perform the vital function of removing
waste from the blood.
Kidney
Nephron
The Ureters
Urine travels from the kidneys to the bladder
through the ureters about every 15 seconds.
Ureters
Tubes that connect the
kidneys to the bladder
The Bladder and Urethra
The bladder stores about 2 cups of urine
comfortably for two to five hours.
Sphincter muscles help keep urine from leaking.
The Bladder and Urethra
The bladder’s sphincter muscles close tightly like a
rubber band around the opening of the bladder into
the urethra.
Urethra
The tube that leads from the bladder to
the outside of the body
Maintaining Your Excretory Health
Healthful behaviors will help keep your
excretory system healthy.
The excretory function removes wastes that can
become toxic from the body.
Maintaining Your Excretory Health
Tips for Maintaining Your Excretory Health
Drink at least eight 8-ounce glasses of water each day.
Limit your intake of caffeine and soft drinks, which can increase
the amount of water lost through urination.
Follow a well-balanced eating plan.
Practice good hygiene.
Get regular medical checkups.
Excretory System Problems
Excretory system problems commonly result
from infection or blockage.
Disorders of the excretory system can have
several different causes, including infection,
blockage of urine, or natural aging.
Excretory System Problems
Cystitis and urethritis are usually caused by a
bacterial infection. Left untreated, the infection can
spread to the kidneys.
Cystitis
Inflammation of the
bladder
Excretory System Problems
Symptoms of cystitis and urethritis include
burning pain during urination, increased frequency
of urination, fever, and possibly blood in urine.
Urethritis
Inflammation of the
urethra
Kidney Problems
Nephritis
Inflammation of the nephrons.
Kidney
Stones
Salts in the urine crystallize into solid stones
and move into the ureter, causing pain and
blocking the passage of urine.
Uremia
Decreased blood filtration by the kidneys
leads to abnormally high levels of nitrogen
waste products remaining in the blood.
Kidney Failure
Kidney failure occurs when the kidneys lose their
ability to function.
It can be caused by infection, decreased blood
flow, or diseases that damage kidney tissue.
Kidney Failure
Hemodialysis takes three to five hours and is
done three or four times per week.
Hemodialysis
A technique in which an artificial
kidney machine removes waste
products from the blood
Kidney Failure
Peritoneal dialysis uses the peritoneum, a thin
membrane that surrounds the digestive organs, to
filter the blood.
Kidney Failure
Kidney transplant involves the replacement of a
nonfunctioning kidney with a healthy kidney from
an organ donor.
After You Read
Reviewing Facts and Vocabulary
1. What is the main function of the excretory
system? What organs are part of it?
The main function is to remove all types of
waste from the body. The organs include the
large intestine, lungs, skin, liver, kidneys, and
bladder.
After You Read
Reviewing Facts and Vocabulary
2. How are a ureter, a urethra, and urethritis
different?
A ureter is a tube that connects a kidney to
the bladder. The urethra leads from the
bladder to outside the body. Urethritis is an
inflammation of the urethra.
After You Read
Reviewing Facts and Vocabulary
3. How can you prevent cystitis and
urethritis?
Practice good hygiene and personal health
to prevent harmful bacteria and infection.