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The Digestive
System
Structures
Identify the basic structures of the
digestive system
Oral Cavity
lips
teeth
tongue
hard and
soft palate
salivary
glands
Teeth
gathers, cuts, grinds food
firmly embedded in bone
carnivores - sharper
herbivores - flatter
deciduous teeth - temporary
teeth that are replaced by
permanent ones
Tooth Anatomy
crown - portion of a tooth
above the gum line or gingiva
covered in enamel
root - portion of a tooth below
the gum line; anchors tooth to
bone
twice as long as the crown
Tooth
Anatomy
incisors - foremost teeth used
to bite into food
canines - longest teeth used
for tearing at food
premolars - teeth used for
crushing and grinding food
molars - caudal most teeth
used for crushing and grinding
food
Dental
Formulas
Numbers represent
tooth
count on ONE side of the
mouth
Upper # represents maxillary
teeth, lower # represents
mandibular teeth
Letter represents type of
tooth.
Canines: {I3/3: C1/1: P4/4:
M2/3} = 42
Oral Cavity, cont.
Saliva - necessary digestive
enzyme produced by salivary
glands
Tongue - skeletal muscle that
aids in chewing
forms a bolus to be swallowed
once food is ground up
Esophagus
layered tube that extends
from the pharynx into the
stomach
peristalsis - organized
contractions that allow
passage of material (food)
sphincter - circular muscle at
end of esophagus that opens
to allow passage of food
Stomach
cardia - inlet region of
stomach associated with
esophagus (sphincter)
body - storage region
fundus - storage region that
allows expansion
antrum - region leading into
small intestine
pyloris - controls flow into
small intestine (sphincter)
Liver
lies directly in front of the
stomach
processes nutrients
secretes bile (secretion that
aids in digestion)
Small Intestine
duodenum - first short section;
associated with pancreas
jejunum - long middle region
ileum - terminal region of
small intestine
Large Intestine
AKA colon
main function is absorption of
water
Rectum
termination of the intestinal
tract
exits the body at anus
(sphincter that controls
defecation)
Additional
peritoneum
smooth
epithelial
Structures
lining of abdomen
mesentery - extension of the
peritoneum; carries blood
vessels and nerves to small
intestine
omentum - surrounds
abdominal organs; also
carries blood vessels
Monogastric
Digestion
Oral Cavity
where food
enters
mechanical
breakdown
begins
saliva starts
digestion
Esophagus
musculome
mbranous
tube
extends
from
pharynx to
stomach
peristalsis
Stomach
chamber,
adds gastric
juices to
food
Hydrochloric
Acid
break food
into smaller
particles
Small
Intestine
complex
tube
takes food
particles not
absorbed by
stomach
duodenum,
jejunum,
ileum
Cecum
blind pouch
at beginning
of large
intestine
little function
Large
Intestine
last major
organ of
tract
main
function =
absorption
of water
reservoir for
waste
Rectum
terminal
portion
opening =
anus
undigested
food passes
as waste
Hind-Gut
Fermenters
guinea pigs,
one
horses, rabbits
stomach
additional
need to
digest plant
fiber from
grass/hay
microbial
fermentation
Oral Cavity
selects
pieces of
forage with
sensitive
prehensile
lips
grinds up
food before
swallowing
Esophagus
carries food
to stomach
enters
stomach at
acute angle
cannot
vomit!!!!
Stomach
small
stomachs
limits
amount of
food intake
continuous
foraging,
picking at
food
Small Intestine
major
digestive
organ
50 - 70% all
nutrients
absorbed
from here
Cecum
hind-gut
first part of
large
intestine
ferments
plant fiber
using
microbes
Large Intestine
similar to
monogastric
absorption
Rectum
terminal
portion
opening =
anus
forms fecal
balls
Ruminant
Digestion
4 chambered
stomach
regurgitation
rumination
lips are
tough
long course
tongues for
grabbing
food
chew and
grind food
LESS
swallows
course bits
Oral Cavity
Esophagus
musculome
mbranous
tube
carries food
to stomach
peristalsis
Stomach
4 chambers
Rumen
Reticulum
Omasum
Abomasum
Rumen
first
chamber
food enters
microbes for
digestion
fermenting
vat
Reticulum
second
chamber
collects
indigestible
particles
(metals)
Rumination
regurgitation
of food for
re-chewing
“chewing
cud”
Omasum
third
stomach
chamber
food enters
after
rumination
Abomasum
fourth
chamber
True
stomach
gastric
juices are
secreted
Small Intestine
complex
tube
moves food
from
stomach to
large
intestine
Cecum
blind pouch
at beginning
of large
intestine
little function
like
monogastric
s
Large Intestine
last major
organ
function =
absorption
reservoir for
waste
Rectum
terminal
portion
opening =
anus
removes
waste
very runny
stool= little
wasted