Transcript PowerPoint

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The organs of the digestive system can be
separated into two groups
 The alimentary canal or gastrointestinal tract –
perform all the functions of digestion as the long,
coiled, hallow, muscular tube winds through the
body
 Accessory digestive organs – assist the digestive
process
Also known as the oral cavity
This is where food enters the body. As it enters the
body it is mixed with saliva and masticated
(chewed)
 It is a mucous membrane lined cavity
 It is protected by the lips
 The cheeks form the sides of the mouth, the hard
palate forms the anterior roof, and the soft palate
forms the posterior roof
 The floor of the mouth is occupied by the muscular
tongue
 At the anterior portion of the mouth are the paired
palatine tonsils (sides) and lingual tonsil (base)
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Subdivided into three parts
 Nasopharynx – the section that part if the
respiratory system
 Oropharynx – posterior to the oral cavity
 Laryngopharnyx – part that connects to the
esophagus
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This area helps to propel food, which is also
known as peristalsis
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Also known as the gullet
Runs from the pharynx, through the
diaphragm, and to the stomach
It is essentially a passageway for peristalsis
It is composed of the same four basic layers
of all the other organs from the esophagus to
the large intestine
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Mucosa – the moist, innermost layer that
lines the cavity
Submucosa – a soft connective tissue layer
just below the mucosa that contains blood
vessels, nerve endings, and lymphatic vessels
Muscularis externa – the smooth muscle layer
which is made up of a circular inner layer and
longitudinal outer layer
Serosa – the outermost wall
C-shaped organ on the left side of the abdominal
cavity that is hidden by the liver and diaphragm
 The stomach acts as a temporary storage tank for
food as well as a site for food breakdown
 The stomach has an additional muscle layer so that
it can move and churn its contents
 It also has various cells that produce digestive
enzymes and gastric juice to break down the food
as well as mucous producing cells to protect the
stomach.
 The processed food is called chyme as it leaves the
stomach and heads for the small intestine.
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It is the main digestive and food absorption
organ
It is the longest part (8-18 feet) of the
alimentary canal and is a long twisted
passageway
It is composed of three areas called the
duodenum, jejunum, and ileum
Walls of the small intestine have microvilli, villi
and circular folds to help increase the surface
area and therefore increase absorption
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Larger in diameter, but shorter in length than
the small intestine
Its main purpose is to dry out the indigestible
food residue by absorbing water and to
eliminate this residue from the body as feces
through the anus
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Produce saliva – a mixture of mucus and
serous fluids
Saliva moistens and binds food together into
a mass called a bolus
Amylase in the serous fluid begins the
digestive process by breaking down the
starch in food
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Helps process food by breaking the food
down into smaller pieces while helping the
food mix with the saliva
Normally an adult will have 32 teeth
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A soft, pink, triangular gland that extends
across the abdomen from the spleen to the
duodenum
Produces a multitude of enzymes that
chemically break down food
The enzyme secretions form the pancreas
enter the small intestine at the duodenum
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Largest gland of the body
Its function in digestion is bile production,
which emulsifies fats
This means the large fat molecules are
separated into smaller molecules. This
increases the surface area and gives fat
digesting enzymes more places where they
can work.
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Small, thin-walled green sac
Stores bile while digestion is not occurring
While being stored, the bile is concentrated
by removing water
If bile is stored too long or too much water is
removed, the cholesterol it contains may
crystallize forming gallstones.
Ingestion – the voluntary act of putting food in the
mouth
 Propulsion – movement of materials through the
digestive system by peristalsis
 Food Breakdown by Mechanical Digestion – physically
fragmenting the materials
 Food Breakdown by Chemical Digestion – chemically
fragmenting the materials
 Absorption – moving usable digested food into the
body
 Defecation - moving unusable digested food out of the
body
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