Download Digestive System

Digestive System
Characteristics
2 Part process to turn food into usable
energy
•  2 Types of Digestion
• 
1.  Physical Digestion – breaks down larger pieces
2.  Chemical Digestion – breaks down complex
chemicals into simpler ones
Physical Digestion
•  Teeth - most physical digestion takes place
•  Adult humans have 32 teeth.
–  8 Incisors - teeth with a single cutting edge
–  4 Canines - round teeth for puncturing.
–  8 Premolars - teeth with several cutting edges for
shredding.
–  12 Molars - teeth with a flat surface for grinding.
Parts of a tooth:
•  Enamel - the smooth, hard covering.
•  Dentin - the porous "bone" of the tooth.
•  Pulp - the cavity containing blood
vessels and nerves.
•  Cementrum - binds the enamel to the
dentin.
Parts of a Tooth
Main Organs
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Mouth
Esophagus
Stomach
Small intestine
Large intestine
** The total length of the digestive
system in an average adult is 8.5
meters (about 28 ft.)
Digestive System
Large
Intestine
Organs that help
•  Liver
•  Gallbladder
•  Pancreas
Mouth
•  The teeth physically break down food
into small particles, saliva begins to mix
with the food.
•  Saliva is a mixture of water, mucus, and
the digestive enzyme called salivary
amylase.
Esophagus
•  Muscular tube connects the
mouth with the stomach.
•  Food passes through this tube by
rhythmic smooth muscle
contractions and relaxations
called peristalsis.
Stomach
Stomach
•  holds 2-3 pints
•  produces about the same
amount of gastric juices every
24 hours.
•  Both mechanical and
chemical digestion occur in
this J-shaped elastic bag
Stomach continued
•  cardiac sphincter is closed, food
cannot reenter the esophagus.
•  pyloric sphincter, located at the lower
end of the stomach, opens to release
food a little at a time.
•  Food usually remains in the stomach for
3-4 hours.
Stomach Continued
•  The outer walls of the stomach are
composed of three layers of muscle
–  circular layer,
–  longitudinal layer, and
–  diagonal layer.
–  Together, these muscles twist and turn the
stomach
Small intestine
•  chemical digestion is completed and
nutrients are absorbed into the blood
stream
•  The lining is highly folded
to form microscopic fingerlike projections called villi
Villi
Large Intestine
•  Also known as your colon
•  1.5 liters of water in the material that
enters the large intestine (9L in small
intestine)
•  Minerals, vitamins, and the rest of the
water are absorbed into the blood
stream from the large intestine
Liver
•  30% of the blood pumped through the
heart in one minute passes through the
liver to be cleaned
•  The liver is the largest gland in the
body, weighing 21/2 to 31/2 pounds.
•  The liver produces bile to be stored in
the gallbladder.
Liver Disease - Cirrhosis
•  Caused by alcohol abuse
(average of 3 drinks/day
over a long period of time)
•  Also caused by chronic
hepatitis C (from sharing
needles in drug use)
Gallbladder
•  Food passing into the small intestine
causes the gallbladder to secrete bile
•  Bile helps liquefy fats to ease their
digestion.
Pancreas
•  Pancreatic fluid is secreted into the
small intestine to break down food
•  Insulin is released to break down sugar
Spleen
•  Most misunderstood organ
•  meshwork of tiny blood vessels
•  it filters the blood and removes
abnormal blood cells
•  it makes disease-fighting components
Fun Fact
To pass through the entire
digestive system takes 18
– 20 hours!
Quiz Yourself!
1.  What type of muscle lines the Esophagus?
2.  What are 3 things that make up saliva?
3.  There is an opening on the top and bottom of your
stomach what are they called?
4.  What are 4 parts of a tooth?
5.  Muscle contractions down the esophagus are
called?
13.  What does the Pancreas Make?
14.  What are two types of digestion and where do they
take place in the body?