Digestive System
 Your body needs fuel to operate
 Just like a car, train, or airplane needs fuel to operate
 The body system that converts fuel to usable energy is
your Digestive System
 This system also helps control the elimination of used-
up fuel in the form of wastes.
 The process of changing food into material the body
can use is called digestion
 Involves both mechanical & chemical processes
 Mechanical Process of digestion
 Chewing and mashing food into smaller pieces
 Chemical Process of digestion
 Breaking food down into
particles with digestive enzymes
 Enzymes are proteins that effect the many body
processes.
 Digestive Enzymes speed up the breakdown of food.
The Mouth and Teeth
 Digestion starts in the mouth
 Teeth tear and grind food
 into small pieces
(Mechanical)
 Taste buds on your tongue sense
flavor & mouth produces saliva (chemical)
 Saliva is a fluid made by the salivary glands that moisten
and softens food, making it easier to swallow.
 Saliva also contains enzymes that help break down food
Stomach & Small Intestine
 Food passes from mouth to esophagus
 The Esophagus is a muscular tube that pushes food down
into the stomach in a process called peristalsis
 Peristalsis is a series of involuntary waves that carry food
particles along.
 Stomach
 Food continues to be broken down
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Glands in stomach wall release gastric juices, a blend of hydrochloric
acid and enzymes. (chemical)
 Hydrochloric acid is strong enough to break down metal
Stomach has protective lining that protects this powerful acid from
digesting itself
Stomach and Small Intestine (cont.)
 Stomach serves as a temporary storage area for food.
 Some food remains in stomach for as long as 4 hours
 Most digestion occurs in Small Intestine
 Small intestine is a coiled, tube like organ that is about 20
feet long.
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Here nutrients separate from
the bulk of the food
Nutrients then enter the
bloodstream and travel to the
body cells where they are used
for growth, energy, and repair.
Organs That Aid Digestion
 Assisted by 3 Important Organs
 Food does NOT pass through
these organs
 Liver
 2nd largest organ in body
 Produces Bile, a substance that helps break
down fats
 Gallbladder
 Stores Bile and releases it into small intestine as needed
 Pancreas
 Makes additional digestive enzymes that are released directly into small
intestine.
 Produces Insulin to help glucose to be absorbed into the body cells
 Diabetes is a disorder of the pancreas.

Pancreas produces too little or no insulin
Excretory (Urinary)
System
 Once all nutrients are extracted from food, all that remains
is liquid and solid waste.
 Body wastes consist of food materials that can NOT be
digested
 Excretory System is your body’s waste removal system
 Process of removing wastes from your body is known as
excretion
http://www.youtube.com/watch?v=XF_lF3J4ZKs
The Process of Excretion
 Food particles that cannot be digested move from the
small intestine to the large intestine, or colon
 Liquid waste is either absorbed in colon, released
through pores in skin (perspiration), or sent to the
kidneys
 Kidneys are organs that filter water and dissolved
wastes from the blood and help maintain proper levels
of water and salts in the body
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Waste materials filtered out by the kidneys leave the body as
urine
Solid waste products that remain are called feces and leave the
body through the anus
Parts of the Excretory System
 Kidneys- Main organs, remove liquid waste (urea)
from the blood
 Ureters- The tubes that carries urine from the kidney
to the bladder
 Bladder- Stores liquid waste before it leaves the body
 Urethra- The tube that releases liquid waste (urine)
from the body
Parts of the Excretory System
Problems of Digestive & Excretory
System
 Have you ever overeaten or ate too fast?
 This discomfort is called Indigestion

Indigestion is body’s way of telling you to eat slowly and
control amount you eat
 Diarrhea (watery feces)
 Food might be contaminated with bacteria
 Heartburn – burning sensation in center of chest or
throat. Has nothing to do with heart
 Result of stomach acids flowing backward into
esophagus
Taking Care of Your Digestive and
Excretory Systems
 Eat a variety of healthy foods. Choose low-fat & high
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fiber foods from all food groups. FRUITS & VEGGY’S
Don’t rush meals
Chew food thoroughly. Don’t wash large pieces down
Drink plenty of water!! Water is good for digestive
system, drink 6 to 8 ounce glasses a day.
Wash hands regularly. Before preparing or eating food
wash hands with soap & water. Always wash after
using the restroom.