A. Two types of digestion
1. Chemical accomplished by
enzymatic breakage of chemical
bonds, resulting in carbs, lipids,
proteins becoming monomers again.
2. Mechanical happens as food is
physically broken into smaller and
smaller pieces
B. Function is to ingest, break down
foodstuffs into monomers, absorb
nutrients, water and eliminate the
undigestible or harmful.
A. Alimentary
canal, GI
tract is
hollow tube
(30 feet)
located in
abdominopelv
ic cavity
B. 1-6 = path of
food
1. Mouth
2. Pharynx
3. Esophagus
4. Stomach
C.There are Four tunics
esophagus to anus.
a. mucosa secretes,
absorbs and protects
(has 3 layers)
b. submucosa dense
connective w/ elastin,
protects & nourishes
c. muscularis externa
(1)inner layer is circular
muscle = peristalsis
(2)outer layer is
longitudinal =
segmentation
d. adventia or serosa is
visceral peritoneum
1. Entry for digestive
system.
2. Accessory organs are
gums, teeth, tongue
(lingual frenulum),
uvula, soft and hard
palate, salivary glands
(parotid) tonsils
(lingual, palantine,
pharyngeal) lips and
cheeks
a. Propels food toward
esophagus
b. Nasopharynx, oropharynx
and laryngopharynx
a. Food tube (10 inches
located behind
trachea) moves food
by peristalsis.
Esophagus is stratified
squamous epithelial
interspersed w/ goblet
cells = mucus to help
bolus slide down and a
double layer of muscle.
a. Function
(1) Mechanical/chemical digestion
(2) Secretes enzymes, mucus and
hormones
(3) Protein digestion
(4) Food storage
b. Anatomy
(1) greater/lesser curvature
(2) Fundus
(3) Cardiac/pyloric regions and
sphincters (superior is
gastroesophageal)
(4) Rugae
(5) 3rd layers of muscle is oblique
(6) Greater omentum can get quite
large
(1) mucous neck
cells- acidic mucus,
(2) parietal cells
(red) secrete HCl
(3) chief cells (blue)
secrete pepsinogen
(4) enteroendocrine
cells- release
hormones gastrin,
CCK, histamine
a. 3 parts = 6 feet
(1) Duodenum 10 inches for
absorption and final stages
of digestion
(2) Jejunum 8 feet
(3) Ileum 12 feet
(4) ileocecal valve
(5)Sphincter of Oddi
controls entry of brush
border enzymes, while
the bile duct controls
entry of bile into Sl.
(6) Microvilli (on villi)
increase surface area of
mucosa. They become
less as distance from
duodenum increases.
(7) Incidence of preyer’s
patches increase as
distance from
duodenum increases.
(8) Brunner’s glands in
submucosa = mucus
6.Plicae circulares are deep, permanent folds
of mucosa and submucosa that force chyme
to spiral thru the lumen, slowing its
movement so that absorption can take place
(1) Duodenum (crypts)
(a)Duodenum with
bile duct from the
liver & pancreatic
duct from pancreas,
is exposed to a
plethora of
digestive enzymes.
(2) Jejunum
(3) Ileum (preyer’s patches)
3 parts
a. Ascending
b. Transverse
c. Descending
d. Anatomy
(1)Hepatic
flexure
(2)Splenic
Flexure
(3)Colon 3 inches in
diameter and 5 feet
long. It becomes the
sigmoid colon which
ends at the rectum
(final 6 inches) as
feces pass out anus
e. Functions
(1) to absorb water, BP,
creation & elimination
of feces
1. Teeth
2. Tongue
3. Liver*
4. Gall Bladder
5. Pancreas*
6. Salivary* and other
*glands
a. Dental formula
Tongue ?
a. Moves food,
which is now
bolus
b. Initiates
swallowing
c. Sensory = Taste
buds
a. Liver is most versatile organ in the body w/
over 200 functions- stores glycogen, makes
bile, detoxifies.
1.Right lobe of liver
2.Left lobe of liver
4. Round ligament
8. Common bile duct
9. Hepatic artery
10.Portal vein
11.Cystic duct
12.Hepatic duct
13.Gallbladder
Arranged in 4 lobules
Stores bile which
emulsifies lipids
a. Located between
stomach and
small intestine.
b. Alpha cells
synthesize &
secrete
pancreatic juice
containing
digestive
enzymes and
hormone
glucagon.
.
a. Secrete salivary
amylase starts
digestion of starch
b. Helps bolus stick
together