DIGESTIVE SYSTEM Flashcards
is composed of several organs which provide
the key functions for the survival of animals
digestive system
physical and chemical breakdown of feeds
as they pass through the gastrointestinal tract
digestion
physical reduction of particle size
Mastication
act of swallowing
Deglutition
bringing
of swallowed food up again to the mouth
Regurgitation
classification of animals
- consume animal
products; such as dogs and cats
carnivores
classification of animals
- consume plant products; such as
cattle, sheep, goat, and horses
herbivores
classification of animals
- consume a
combination of plant and animal products; such as humans and pigs
omnivores
type of digestive system
- simple stomach such as in
birds, dogs, and pigs
monogastric
type of digestive system
- multi-compartmented stomach, this
was referred to as compound stomach, are cranial fermenters, such as cattle,
goats, and sheep
ruminants
type of digestive system
- animals with simple
stomach, but with very large and complex large intestine such as horses,
rabbits, and ostrich
hind gut (caudal) fermenters
oral cavity
- is the entrance to the digestive system
- are used primarily for grinding
food and mixing it with saliva
- may also serve as
a prehensile organ for grasping food, and as a defensive and offensive
weapon
oral cavity or the mouth
oral cavity
- referring to the outer part, between the teeth and the lips (labia) and cheeks
the oral vestibule
oral cavity
- enclosed by the teeth and the dental pad, which
contains the tongue and communicate with the oral part of the pharynx.
oral cavity proper
part of teeth
- the part that protrudes
above the gum line
crown
part of teeth
- the part found at the gum line
neck
part of teeth
- the part
embedded in the tooth socket
root
teeth according to permanence
- milk tooth; present at birth
temporary teeth
teeth according to permanence
- persist throughout the life of the animals
adult teeth
prominent transverse folds of thick mucous membrane covering the hard palate
palatine rugae
All domestic animals develop a set of deciduous teeth (milk teeth) that eventually
fall-out and are replaced with permanent teeth this is called?
diphyodont
teeth according to function
- cutting teeth –
nippers
Incisors
teeth according to function
- tearing or seizing
teeth – holding teeth
Canines
teeth according to function
- grinding or shearing teeth
Premolars and Molars
layers of teeth - the visible, outer layer; extremely hard; composed primarily of calcium phosphate minerals; irreplaceable, as the cells that generate it (ameloblasts) are lost following formation of the tooth, except continuously growing teeth
Enamel
layers of teeth - middle layer of the tooth, the layer directly beneath the surface enamel; yellowish in color, with a center (dental cavity)
Dentin
layers of teeth
- center layer; softest layer,
containing vital tissues composed of
blood and nerves
Pulp
teeth based on the manner of growth
- found in carnivores, omnivores and incisors
of ruminants, possess a crown, a neck, and a root
- grows to adult size, but wears-off without further growth, and with no eruption
to compensate for the wear
true teeth
teeth based on the manner of growth
- tushes of pigs and incisor teeth of rodents do not possess a definite neck or
root.
- continuously grows from active pulp
constantly growing teeth
teeth based on the manner of growth
- entire dentition of horses and cheek
teeth of ruminants, possess extremely long root and no definite neck
- gradually pushed out of the sockets to compensate for the wear
constantly erupting teeth
teeth based on the amount of development
- dentition when all teeth are similar
Homodont
teeth based on the amount of development
- dentition when teeth have different appearances such
as incisors, canine, premolars, and molars.
Heterodont
teeth based on the amount of development
- dentition when much of the crown is embedded in the
gum, e.g. cheek teeth of horse.
Hypsodont
teeth based on the amount of development
- dentition when several primitive cones come together to
form one tooth, e.g. cheek teeth of the pig.
Bunodont
teeth based on the amount of development
- dentition when the cones become ridges, e.g. cheek
teeth of the horse.
Lophodont
teeth based on the amount of development
- dentition when the ridges become sharp, e.g. cheek
teeth of ox.
Selenodont
teeth based on the amount of development
- dentition when the enamel of the tooth is restricted to
the crown, e.g. teeth of dog (short crowned teeth).
Brachydont
parts of tongue
- free part at the rostral end
apex
parts of tongue
- the muscular part
body
parts of tongue
- the caudal part adjacent to the pharynx.
- It is covered with thick keratinized stratified squamous epithelium
- the
dorsal surface contains a large number of projections (lingual papillae)
root
five types of lingual papillae
- are the most numerous of the lingual papillae; fine,
small, cone-shaped papillae (hair-like) covering most of the dorsum
of the tongue.
Filiform papillae
five types of lingual papillae
- are club shaped projections, scattered amongst
the filiform papillae and have taste buds.
Fungiform papillae
five types of lingual papillae
- are short vertical folds, appear as a series of red
colored, leaf–like ridges of mucosa and bear many taste buds.
Foliate papillae
five types of lingual papillae
- are dome-shaped,
large, circular projections surrounded by a deep groove and with
taste buds.
Circumvallate papillae (or vallate papillae)
five types of lingual papillae
- one of the sparsely scattered elevations on the
tongue, often considered to be modified filiform papillae.
Conical papilla
lingual papillae that are found in all domestic animals
filiform, fungiform, and vallate papillae
lingual papillae that are present in the horse, pig, and dog, but not in ruminants
foliate papillae
lingual papillae that is present in ruminants and large in size
conical papillae
lingual papillae that do not bear taste
filiform and conical papillae
serves as the common passageway for food and air, and
is located caudal to the oral and nasal cavities. It is lined by mucous
membrane and surrounded by muscles
Pharynx
3 parts of pharynx
- nasopharynx
- oropharynx
- laryngopharynx
is a muscular tube extending from the pharynx
(oropharynx) to the stomach, until immediately caudal to the diaphragm
Esophagus
parts of esophagus based on location (3)
- cervical
- thoracic
- abdominal
esophagus of animals based on muscular control
- is
voluntary as far as at the level near the base of the heart
- has a well-marked cardiac sphincter thus vomiting is extremely rare
horse
esophagus of animals based on muscular control
- voluntary, but only until few inches near the cardia.
pig
esophagus of animals based on muscular control
- is easily dilatable
and voluntary throughout
ruminants (cattle and sheep)
esophagus of animals based on muscular control
- voluntary
throughout.
dog
parts of stomach
- entrance to the stomach and proximal to the heart
cardia
parts of stomach
- body, has greater curvature (convex side) and lesser curvature
(concave side)
fundus
parts of stomach
- connected to the small intestine
pylorus
circular muscles of stomach
- muscular ring
- separates the stomach from the esophagus
Cardiac sphincter
circular muscles of stomach
- strong annular muscle
- at the junction of the stomach and the duodenum
Pyloric sphincter
allow the stomach volume to expand to accommodate meals
gastric folds
depression created by deep infoldings of the columnar epithelium of the tunica mucosa
gastric pits
layers of stomach (nonruminants)
- that covers the outer surface
of the stomach and continuous with the parietal peritoneum
tunica serosa
layers of stomach (nonruminants)
- composed of three smooth muscle layers – outer longitudinal,
middle circular, and internal oblique muscles
tunica muscularis
layers of stomach (nonruminants)
- containing blood vessels and nerves
tunica submucosa
part of tunica mucosa
- has no glands and composed of squamous epithelium
esophageal part
part of tunica mucosa
- which contains gastric glands
glandular part
part of glandular part
- adjacent to the esophageal region, contains
cardiac glands (also called mucous glands), and no enzymes are
produced in this region
Cardiac region
part of glandular part
- the body of the stomach, contains fundic glands
(or true gastric glands) composed of 3 types of cells: chief cells, parietal cells, neck chief cells
Fundic region
part of glandular part
- contains pyloric glands that secrete mucus and small
amount of proteolytic enzymes.
Pyloric region
cells of fundic region
- pepsinogen (a zymogen or precursor or pepsin used to break down
proteins into smaller peptides)
chief cells
cells of fundic region
- secrete
hydrochloric acid.
parietal cells
first three compartments of ruminant stomach
- rumen
- reticulum
- omasum
- is voluminous diverticula marked expansion of the esophageal region - is lined with nonglandular stratified squamous epithelium where ingesta are subjected to microbial digestions
forestomach
- is a small glandular portion of the ruminant stomach - considered as the true stomach of ruminants - secretes gastric enzymes and hydrochloric acid
terminal compartment or abomasum
appearance of ruminant stomach compartments
- honey-comb; smallest section; most
anterior of the compartments; lies entirely on the left
median plane; acts as a liquid reservoir to soften heavy
matter in food
Reticulum
appearance of ruminant stomach compartments
- paunch; largest part of the adult compound
stomach; fermentation vat, an organ of maceration, a
site of bacterial digestion and an organ of absorption
Rumen
appearance of ruminant stomach compartments
- many plies; grinds food more finely and
absorb excess moisture; broad longitudinal folds or
leaves reminiscent of the pages in a book; not concern
in rumination
Omasum
part of abomasum
- anterior
end
fundic portion
part of abomasum
- posterior extension
of the fundus
body
part of abomasum
- connected to the
small intestine
pyloric part
tube connecting the stomach to the cecum and large
intestine; suspended from the dorsal part of the abdominal
cavity by a fold of peritoneum called great mesentery ;
absorption of nutrients from gastric and intestinal digestion
occurs
Small Intestine
it is called the fold of peritoneum
great mesentery
part of small intestine
- makes-up 5% of the total length of the small
intestine. It has an s-shaped portion which contains the pancreas
duodenum
part of small intestine
- makes-up 90% of the total length and has not clear
demarcation from other portions of the small intestine.
- forms the
mesenteric part of the intestine, and generally located in the left
dorsal position of the abdominal cavity.
jejunum
part of small intestine
- makes-up about 4 to 5% of the total length of the
intestine. This portion is connected to the cecum and large intestine
ileum
type of glands of small intestine
- are found throughout the small
intestine
intestinal glands or crypt of lieberkuhn or intestinal crypt
type of glands of small intestine
- are found in the first part of
the small intestine, and produce mucus-rich alkaline secretions
duodenal glands or brunner’s glands
type of glands of small intestine
- associated with the immune system
Peyer’s
patches
cells of crypt of lieberkuhn
- secrete mucus for
lubrication and protection
goblet cells
cells of crypt of lieberkuhn
- secrete water and electrolytes
enterocytes
cells of crypt of lieberkuhn
- secrete hormones such as somatostatin, motilin,
cholesystokinin, neurotensin, vasoactive intestinal peptides, and
enteroglucagon
enteroendocrine cells
cells of crypt of lieberkuhn
- secrete antimicrobial peptides
Paneth cells
reabsorbs the water and electrolytes
villi
part of large intestine
- a blind sac situated between the ileum
and the colon. It has a comma-shaped appearance and lies to the right of the
median plane. It consists of body, base, and apex
cecum or cul de sac
part of large intestine
- a coiled tubular organ
responsible in absorbing water from digested food
colon
part of colon (3)
- ascending colon
- transverse colon
- descending colon
part of colon
- forms a short connection that runs
transversely from the distal ascending colon to proximal
descending colon, running from right to left side of the
abdomen
transverse colon
part of colon
- relatively straight, running caudad on the
left side of the abdomen to the pelvic cavity, where it
terminates as the rectum
descending colon
part of large intestine
- the terminal part of the large intestine and is found
within the pelvic cavity. It serves as a temporary storage for feces
rectum
part of large intestine
- is the terminal part of the alimentary tract and is continuous
with the skin
anus
muscles of anus
- a circular smooth muscle
sphincter ani internus
muscles of anus
- composed of skeletal muscle fibers and adhere intimately to the skin
surrounding the margin of the anus
sphincter ani externus
muscles of anus
- for retraction of partially
prolapse anus during defecation
retractor ani
peritoneal structures
- holds the liver to the ventral midline
falciform ligament
peritoneal structures
- connecting the spleen and left kidney
renosplenic or nephrosplenic ligament
peritoneal structures
- connecting the liver and proximal duodenum
hepatoduodenal ligament
peritoneal structures
- part of the peritoneum that connects the stomach with
other visceral organs
omentum
part of omentum
- extends from the lesser curvature of
the stomach to the liver
lesser omentum
part of omentum
- attached to the greater
curvature of the stomach)
greater omentum
provide necessary digestive enzymes, and
provide a route of excretion of substances which accumulate on the teeth,
and provide lubricative and cleansing functions
Salivary Glands
type of salivary gland - located ventral to the ear in relation to the caudal border of the mandible - secretes primarily serous saliva
parotid salivary gland
type of salivary gland
- located ventral to the parotid, just caudal to the mandible
- are mixed
glands in domestic farm animals
mandibular salivary
gland
type of salivary gland
- located deep to the mucous membrane along the
ventral side of the lateral surface of the tongue near the floor of the mouth
sublingual salivary gland
minor salivary glands (4)
- labial
- buccal
- lingual
- palatine glands
salivary glands based on type of secretion
- that produce a watery clear fluid
serous glands
salivary glands based on type of secretion
- that secrete, a viscous material that acts as a protective covering for
the surface of mucous membranes
mucous
glands
salivary glands based on type of secretion
- that produce both
mucous and serous fluids
mixed glands
is a compound gland, which is irregularly lobulated and
lies adjacent to the proximal duodenum
Pancreas
part of pancreas
- responsible in producing sodium bicarbonate and digestive enzymes
through pancreatic duct
exocrine portion
part of pancreas
- consists of isolated groups
of pale-staining cells scattered throughout the gland called the pancreatic
islets (formerly islets of Langerhans).
endocrine portion
- are responsible in
producing the hormones that pass directly into the bloodstream most notably
glucagon and insulin - the primary regulators of blood sugar levels
pancreatic islets
cells within the pancreatic islets
- responsible in producing glucagon for increasing blood glucose level
alpha cells
cells within the pancreatic islets
- responsible in producing insulin for decreasing and utilization of blood
glucose by body tissues
beta cells
cells within the pancreatic islets
- responsible in producing somatostatin
which inhibits the release of numerous other hormones in the body
delta cells
- s considered as the largest gland in the body (about 1 to 2%
of the total adult body weight) - situated posterior to the diaphragm and
conforms closely to the shape of the structure
liver
blood enters the liver via?
hepatic artery and portal vein
branch of the celiac
artery
hepatic artery
main trunk of
the portal system
portal vein
blood leaves the liver via?
hepatic vein
enters the posterior
vena cava
hepatic vein
is for the storage of bile in all domestic animals except horses
gallbladder
The morphologic unit of the
liver
hepatic lobule
a polygonal cylinder of liver cells
hepatocytes
- At the angles on the periphery, where adjacent hepatic lobules meet - consisting of branches of the hepatic artery and portal vein (interlobular vessels), an interlobular bile duct, and lymphatics
portal triads
In and around the sinusoids are
fixed macrophages
Kupffer
cells
liver lobes of equine
right, middle or central, and left lobes
liver lobes of bovine
not divided into lobes
liver lobes of porcine
right lateral, right medial, left lateral, left medial
liver lobes of canine
left lateral, left central, right central, right lateral, and caudate lobe
the rhythmic, coordinated contraction of muscles to
move ingesta along the GIT
Peristalsis
contract behind the
food mass.
circular muscles
contract ahead of food mass
longitudinal muscles
avian digestive system
- the palate is incompletely fused resulting in a longitudinal opening
between oral and nasal cavities
choanal cleft
avian digestive system
- the esophagus features a distensible dilation
crop or ingluvies
avian stomach
- which provides pepsin, and hydrochloric acid for enzymatic
digestion
proventriculus or glandular
stomach
avian stomach
- which
has a highly keratinized mucosa, has a cuticle which forms a thick, leathery
sheet, and has grit
gizzard or muscular stomach (or ventriculus muscularis)
avian digestive system
- remnant of the embryonic connection to
the yolk sac
Meckel’s diverticulum
avian digestive system
- large intestine has an expanded region
- common to
the both gastrointestinal and urogenital tracts
cloaca
portion of cloaca
- that temporarily holds feces
coprodeum
portion of cloaca
- that has openings for two ureters
urodeum
portion of cloaca
- that houses the male reproductive organs (or has opening for the
female reproductive tract)
- also has the opening of the bursa of Fabricius
proctodeum
avian digestive system
- referred to as the vent in birds, is the terminal part.
anus
terminates at the large intestine
ileum
avian digestive system
- a point
demarcated clearly in domestic birds by the presence of
paired ___
ceca
avian digestive system
- provides for temporary storage after
swallowing
crop
avian digestive system
- provides a
muscular force to grind and crush foodstuffs so
that they can be more effectively digested.
gizzard