The Digestive System
Dr. Ali Ebneshahidi
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
, Functions of the Digestive System
ingestion – the oral cavity allows food to enter the digestive
tract and have mastication (chewing) occurs , and the resulting
food bolus is swallowed .
Digestion:
Mechanical digestion – muscular movement of the digestive
tract (mainly in the oral cavity and stomach) physically break
down food into smaller particles .
chemical digestion – hydrolysis reactions aided by
enzymes (mainly in the stomach and small intestine)
chemically break down food particles into nutrient
molecules , small enough to be absorbed . .
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
, Secretion – enzymes and
digestive fluids secreted by
the digestive tract and its
accessory organs facilitate
chemical digestion .
Absorption – passage of the
end – products (nutrients) of
chemical digestion from the
digestive tract into blood or
lymph for distribution to
tissue cells .
Elimination – undigested
material will be released
through the rectum and anus
by defecation .
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
, Organization of The Digestive System
Organs of the digestive system are divided into 2 main
group : the gastrointestinal tract (GI tract) and
accessory structures .
GI tract is a continuous tube extending through the
ventral cavity from the mouth to the anus – it consists
of the mouth , oral cavity , oropharynx , esophagus ,
stomach , small intestine , large intestine , rectum , and
anus .
Accessory structures include the teeth, tongue (in oral
cavity) , salivary glands , liver , gallbladder , and
pancreas .
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Dr. Ali Ebneshahidi
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
, Functions of the Digestive System
ingestion – the oral cavity allows food to enter the digestive
tract and have mastication (chewing) occurs , and the resulting
food bolus is swallowed .
Digestion:
Mechanical digestion – muscular movement of the digestive
tract (mainly in the oral cavity and stomach) physically break
down food into smaller particles .
chemical digestion – hydrolysis reactions aided by
enzymes (mainly in the stomach and small intestine)
chemically break down food particles into nutrient
molecules , small enough to be absorbed . .
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
, Secretion – enzymes and
digestive fluids secreted by
the digestive tract and its
accessory organs facilitate
chemical digestion .
Absorption – passage of the
end – products (nutrients) of
chemical digestion from the
digestive tract into blood or
lymph for distribution to
tissue cells .
Elimination – undigested
material will be released
through the rectum and anus
by defecation .
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
, Organization of The Digestive System
Organs of the digestive system are divided into 2 main
group : the gastrointestinal tract (GI tract) and
accessory structures .
GI tract is a continuous tube extending through the
ventral cavity from the mouth to the anus – it consists
of the mouth , oral cavity , oropharynx , esophagus ,
stomach , small intestine , large intestine , rectum , and
anus .
Accessory structures include the teeth, tongue (in oral
cavity) , salivary glands , liver , gallbladder , and
pancreas .
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
