Download digestive system powerpoint

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
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.
Hard Palate and Soft Palate
• 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
• 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 feet 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 indigestable 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.