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Digestive system
Function the Digestive System
 Digestion
Breakdown of ingested food
 Absorption
 Passage of nutrients into the blood
 Metabolism
 Production of cellular energy (ATP)
The Digestive System
 Two main
groups
 Alimentary
canal.
 Accessory
digestive
organs.
Organs of the Alimentary Canal
 Mouth
 Pharynx
 Esophagus
 Stomach
 Small intestine
 Large intestine
 Anus
Mouth (Oral Cavity)
 Vestibule; space
between lips
externally and teeth
and gums internally.
 Oral cavity proper;
area surrounded by
the teeth and gums,
containing the
tongue.
Mouth (Oral Cavity)
 Lips (labia); protect
the anterior opening
 Cheeks; form the
lateral walls.
 Hard palate; forms
the anterior roof.
 Soft palate; forms
the posterior roof.
 Uvula; fleshy
projection of the
soft palate.
 Tongue; lies in the middle of
the cavity attached at hyoid
and styloid processes of the
skull, and by the lingual
frenulum
tongue
Pharynx
 Muscular tube extends
from base of skull to be
continues with the
esophagus.
 It is divided into;
 Nasopharynx , posterior
to nasal cavity
 Oropharynx , posterior
to oral cavity
 Laryngopharynx ,
posterior to larynx
Esophagus

Muscular tube,
continuation of the
pharynx.

Runs from pharynx.
through the thoracic
cavity, piercing the
diaphragm, to end in the
stomach.

Conducts food and fluid.
Stomach

Located on the left side of the
upper part of the abdominal
cavity.

Composed of upper and lower
ends, anterior and posterior
surfaces, lesser and greater
curves.

Divided into the following
regions;
 Cardiac region; near the
upper end, (heart).
 Fundus
 Body
 Phylorus; funnel-shaped
terminal end.
peritoneum
 Serous membranes lines the
abdominal and pelvic cavities and
covers the related organs.
 It is attached to the stomach curves.
 Lesser omentum; attaches the liver
to the lesser curvature.
 Greater omentum; attaches the
greater curvature to the transverse
colon, and then to the posterior
body wall.
 Contains fat, blood vessels,
lymphatic vessels, lymph nodes
and nerve plexuses;
 Help to insulate, cushion, and
protect abdominal organs.
 Transmit blood, lymph and nerve
supply to the abdominal organs.
Small Intestine
 Muscular tube extending
form the stomach (the
pyloric sphincter) to the
commencement of the
large intestine (ileocecal
valve).
 The body’s major
digestive organ.
 Site of nutrient absorption
into the blood stream.
Subdivisions of the Small Intestine
Fixed part;
 Duodenum
 Attached to the pyloric
end of the stomach.
 C shape, curves around
the head of the pancreas.
 It is the site for
digestion.
Subdivisions of the Small Intestine
Mobile part;
 Jejunum
 Constitutes 2/5 of the length.
 Attaches to the duodenum.
 Ileum
 Constitutes 3/5 of the length.
 Extends from jejunum to
commencement of large
intestine, (ileocecal valve).
 Both Jejunum, and Ileum are the
site for digestion.
Large Intestine
 Large diameter
muscular tube, extends
from the end of the
small intestine to the
rectum.
 Larger in diameter, but
shorter than the small
intestine.
 Frames the small
intestine in the
abdominal cavity.
Structures of the Large Intestine
 Cecum – saclike
first part of the
large intestine.
 Appendix. hangs
from the cecum.
Structures of the Large Intestine
 Colon
 Ascending
 Transverse
 Descending
 S-shaped
sigmoidal
 Rectum
 Anus; external
body opening
Accessory Digestive Organs
 Salivary glands
 Teeth
 Pancreas
 Liver
 Gall bladder
Salivary glands
 Saliva-producing
glands are three
pairs.
 Parotid glands,
located anterior
to ears.
 Submandibular
glands, below
the mandible.
 Sublingual
glands, below
the tongue.
Teeth
 Humans have two
sets of teeth
 Deciduous (baby
or milk) teeth 20
teeth are fully
formed by age
two.
 Permanent , 32
teeth, fully
formed by 20
years.
Classification of Teeth
Figure 14.9
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide
Pancreas
o Endocrine and exocrine
gland .
o Lies behind the
stomach.
oComposed of head,
body, tail and uncinate
process.
oIts head lies in the
concavity of the
duodenum.
oThe body Lies behind
the stomach.
oIts tail lies in relation to
the spleen
Liver
 Largest gland in the body
 Located on the right side of
the upper part of the
abdominal cavity under the
diaphragm
 Consists of four lobes
 Connected to the gall
bladder via the common
hepatic duct
Gall Bladder
 It is a small sac found
in hollow fossa of
inferior surface of the
liver.
 Connected to the
liver via the common
hepatic duct
 Stores, and
concentrates bile.
 Connected to the
duodenum by the bile
duct.