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The Digestive
System
By: Jama Willbanks, MS, NREMT-P
The Alimentary Canal

A long muscular tube that begins at the
mouth and includes the oral cavity, pharynx,
esophagus, stomach, small intestines, and
large intestines.
The Alimentary Canal
The
accessory organs include the
salivary glands, tongue, teeth, liver,
gallbladder, and pancreas.
The Mouth

Food is tasted,
broken down by teeth,
lubricated and
partially digested by
saliva.
The Teeth

Break down food by
chewing and grinding
(mastication).
The Tongue
The Tongue



Muscular organ.
Contains special
receptors called taste
buds.
Aids with chewing and
swallowing food.
Hard Palate and Soft Palate
Hard palate: a bony structure that forms
the roof of the mouth and separates the
mouth from the nasal cavities.
 Soft palate: behind hard palate, separates
the mouth from the nasopharynx.

Salivary Glands


The parotid, sublingual, and submandibular
glands produce a liquid called saliva.
Saliva lubricates the mouth during speech and
chewing and moistens food so it can be
swallowed easily.
Salivary Glands


Saliva contains an enzyme called salivary
amylase.
Salivary amylase begins the chemical
breakdown of carbohydrates or starches into
sugars that can be taken into the body.
Salivary Glands at Work
Bolus

After the food is chewed
and mixed with saliva, it is
called a bolus.
The Pharynx (Throat)


The pharynx is a tube that carries both
air and food.
It carries the air to the trachea and food
to the esophagus.
The Esophagus


The esophagus is the muscular tube posterior
to the trachea that receives the bolus from the
pharynx and carries it to the stomach.
The esophagus relies on peristalsis, a
rhythmic, wavelike, involuntary movement of
its muscles to move the food in a forward
direction.
The Stomach


The stomach receives food from the
esophagus.
The mucous membrane lining of the stomach
contains folds called rugae that disappear as
the stomach fills with food and expands.
Stomach


Food usually remains in the stomach for
about one to four hours.
During this time, food is converted into a
semifluid material called chyme by gastric
juices produced by glands in the stomach.
The Small Intestine

When the food, in the
form of chyme, leaves
the stomach it enters
the small intestine.
Purpose of the Small Intestine

Products of digestion are absorbed into the
bloodstream for use by the body cells.
The Small Intestine

The small intestine is a coiled section of the
alimentary canal about twenty feet long and
one inch in diameter.
Villi

Walls of small
intestine are lined
with villi that
contain blood
capillaries and
lacteals.
The Small Intestine
 It
is divided into three sections:
duodenum, jejunum, and ileum.
Duodenum


The first nine to ten inches of the small intestine.
Bile from the gallbladder and liver and
pancreatic juice from the pancreas enter this
section through ducts or tubes.
Jejunum & Ileum




The jejunum is about eight inches long.
It forms the middle section of the small
intestine.
The Ileum is the final 12 feet and connects
with the large intestine at the cecum.
The ileocecal valve prevents backflow.
Large
Intestine


Approximately 5 feet
long.
Approximately 2 inch
diameter.
Purpose of Large Intestine




Absorption of water and any remaining
nutrients.
Storage of indigestible materials before they
are eliminated.
Synthesis and absorption of some vitamins.
Transportation of waste.
Purpose of Large Intestine

Transportation of waste.
Sections of the Intestine


Cecum
Colon
 Ascending
 Transverse
 Descending
 Sigmoid Colon
• Rectum: final six to eight inches.
Big Word of the Day
Esophagogastroduodenoscopy
esophagus
gastric
duodenum
scope
We’ll just call it EGD
 EGD: A diagnostic
test used to aid in
identifying abnormalities of the
esophagus, stomach, and small
intestines.
 Abnormalities such as: esophagitis,
inflammatory bowel disease, ulcers,
tumors, gastritis, and polyps.
Accessory Organs
 Liver
 Gallbladder
 Pancreas
Liver




Largest gland in the body.
Located under the diaphragm and in the upper
right quadrant of the abdomen.
Secretes bile which is used to emulsify fats in
the digestive tract.
Bile also makes fats water soluble (which is
necessary for absorption).
Liver




Stores sugar in the form of glycogen.
Glycogen is converted to glucose and
released into the bloodstream when needed.
Stores iron and certain vitamins.
Produces heparin which prevents clotting in
the blood.
Liver



Produces blood proteins such as fibrinogen and
prothrombin which aid in clotting of the blood.
Detoxifies substances such as alcohol and
pesticides.
Destroys bacteria.
Gallbladder



Small, muscular sac located under the liver and
attached to it by connective tissue.
Stores and concentrates bile which it receives
from the liver.
Gallbladder contracts to push bile through the
common bile duct and into the duodenum.
Pancreas



Located behind the stomach.
Produces pancreatic juices which contain
enzymes to digest food.
Produces insulin which regulates the
metabolism of glucose into energy.