Digestive System Flashcards
Feeding
prehension
GIT
Gastrointestinal Tract
physical and chemical breakdown of feeds as they pass through the gastrointestinal tract.
Digestion
physical reduction of particle size.
Mastication (chewing)
act of swallowing
Deglutition (swallowing)
bringing of swallowed food up again to the mouth.
Regurgitation (especially in ruminant
animals)
animal products o Dogs, cats
Carnivore
plant products o cattle, sheep, goat, horses
Herbivore
combination of plant and animal products o Humans, pigs
Omnivore
chickens, pigs, turkeys, dogs, cats, Type of DS
Monogastric (simple stomach)
compound stomach, are cranial fermenters.
cattle, goats, sheep
Ruminants (multi-compartmented
stomach)
animals with simple stomach but with very large and
complex large intestine.
horses, rabbits, ostrich
Hind gut (caudal) fermenters
Major Structures
Oral cavity, pharynx, esophagus, stomach, small intestines, large intestines
Accessory organs
liver, gallbladder, pancreas, salivary glands
entrance of the DS. Used primarily for grinding food and mixing it with saliva but may also serve as a prehensile organ (grasping mechanism and as a defensive and offensive weapon).
Oral Cavity (mouth)
Oral Cavity is divided by the teeth into: outer part, between the teeth and the lips (labia) and cheeks.
oral vestibule
Oral Cavity is divided by the teeth into: enclosed by the teeth and the dental pad.
oral cavity proper
Teeth 3 major parts
crown, neck, root
protrudes the gum line
crown
part found at the gum line
neck
embedded in the tooth socket
root
tooth present at birth.
Temporary Teeth (milk tooth)
persist throughout the life of the animals.
Adult Teeth
Types of Teeth: cutting teeth (nippers)
Incisors
Types of Teeth: tearing or seizing (holding teeth)
Canines
Types of Teeth: grinding and shearing.
Premolars and Molars
visible outer layer, which is considered as the hardest substance in the body. Made of calcium phosphate minerals and considered irreplaceable as the cells that generate it (ameloblasts) are lost following the formation of the teeth, except for continuously growing teeth.
Enamel
middle layer, is the layer directly beneath the surface enamel. This layer is yellowish in color and with a dental cavity at the center.
Dentin
center layer, is the softest layer containing vital tissues composed of blood vessels and nerves.
Pulp
carnivores, omnivores, and incisors of ruminants possess crown, neck, and root.
Grows to adult size; wear away without further growth, and no eruption to compensate for the wear.
True Teeth
tushes of pig and incisor teeth of rodents.
Do not possess a definite neck or root;
grow from persistent active pulp.
Constantly Growing Teeth
entire dentition of equine and cheek teeth of
ruminants; possesses extremely long root and no definite neck; filling in of bone pushes the teeth out of the socket to compensate for the wear.
Constantly Erupting Teeth
all teeth are similar
Homodont definition
all teeth have gone differentiation. incisors, canine, molars, premolars.
Heterodont definition
when several primitive cones come together to form
one tooth,
- cheek teeth of the pig.
Bunodont dentition
when the cones become ridges.
- cheek teeth of the horse
Lophodont dentition
when the ridges become sharp.
- cheek teeth of ox
Selenodont dentition
when the enamel of the tooth is restricted to the
crown.
- teeth of dog (short crowned teeth)
Brachydont dentition
when much of the crown is embedded in the gum.
- cheek teeth of horse.
Hypsodont dentition
Tongue: divided parts
free part at the rostral end.
apex
Tongue: divided parts
muscular part (meaty)
body
Tongue: divided parts
caudal part adjacent to the pharynx
root
Tongue is covered with?
thick keratinized stratified
squamous epithelium.
Surface is characterized by a large number
of projections , the papillae,
which are particularly well developed on the
dorsal surface.
lingual papillae
most numerous of the lingual papillae; fine, small, cone shaped papillae (hair-like) covering most of the dorsum of the tongue.
Filiform papillae
are club shaped projections, scattered amongst the
filiform papillae and have taste buds.
Fungiform papillae
are short vertical folds, appear as a series of red colored, leaf–like ridges of mucosa and bear many taste buds.
Foliate papillae
(or vallate papillae) - are dome-shaped, large,
circular projections surrounded by a deep groove and with taste buds.
Circumvallate papillae
one of the sparsely scattered elevations on the tongue, often considered to be modified filiform
papillae.
Conical papilla
filiform, fungiform, and vallate papillae, found in?
found in all domestic animals
present in the horse, pig, and dog, but not in ruminants.
foliate papillae
have large conical papillae.
ruminants
papillae that do not bear taste, but all other types of papillae do
Filiform and Conical
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
Pharynx 3 regions
a) Nasopharynx
b) Oropharynx
c) Laryngopharynx
Is a muscular tube extending from the
pharynx (oropharynx) to the stomach, until
immediately caudal to the diaphragm.
Esophagus
Esophagus 3 parts (based location)
- Cervical
- Thoracic
- Abdominal parts
voluntary as far as the base of the heart. has a well-marked cardiac sphincter thus vomiting is extremely rare. It is the only domestic animal in which acute
gastric dilatation can occur to the point of
rupture of the stomach wall without vomiting
horse
vomit easily.
Carnivores and Omnivores
esophagus is also voluntary, but only until few inches near the cardia.
Pigs
easily dilatable and voluntary throughout.
Ox/sheep
voluntary throughout
dog
dogs, horses, and pigs have
simple stomach
The old term ________ is discouraged
because it perpetuates the misconception
that ruminants possess more than one
stomach, although the ruminant actually has
a single stomach with multiple compartments.
Monogastric
Simple Stomach regions: (entrance) - proximal to the heart
Cardia
Simple Stomach regions: has greater curvature (convex side) and lesser curvature (concave side),
large bulge
Fundus
Simple Stomach regions: connected to the small intestine.
Pylorus
Simple Stomach Regions: – greater curvature and pyloric region (outflow)
body
__ how many distinct circular muscles are found in
the entrance and exit of the stomach,
namely:
Cardiac sphincter and Pyloric sphincter
muscular ring, separates the stomach from the esophagus.
Cardiac sphincter
strong annular muscle, at the junction of the stomach and duodenum. The junction of the
stomach and the duodenum.
Pyloric sphincter
Stomach has _____ that allow it to
expand to increase volume and
accommodate more food.
gastric folds
The lining of the stomach has ________ created by deep infoldings of the
columnar epithelium of the mucosa.
gastric pits or depressions
Stomach – Non ruminants: 4 layers
Tunica Serosa, Tunica Muscularis, Tunica Submucosa, Tunica Mucosa
covers the outer surface of the stomach and continuous with the parietal peritoneum.
Tunica Serosa
composed of three smooth muscle layers – outer longitudinal, middle circular, and internal oblique muscles.
Tunica Muscularis
containing blood vessels and nerves.
Tunica Submucosa
containing blood vessels and nerves.
Tunica Submucosa
Tunica Mucosa has 2 parts
Esophageal part and Glandular part
has no glands and composed of squamous epithelium
Esophageal part
which contains gastric glands
- Glandular part
Glandular part have __ regions
Cardiac, Fundic, Pyloric
closest to the esophageal region, contains cardiac
gland (mucous glands), do not produce enzyme.
Cardiac region
body of the stomach, contains fundic glands (true gastric glands, composed of 3 types of cells,
body chief cells, neck chief cells, and parietal cells.
Fundic region
pyloric glands – secretes mucus and small amount of
proteolytic enzymes, no parietal cells.
Pyloric region
The Ruminant stomach is a single stomach
composed of __ compartments
4
The Ruminant stomach is a single stomach
composed of?
Rumen, Reticulum, Omasum,= (forestomach) Abomasum
The terminal compartment is a small
glandular portion of the ruminant stomach
called___
Abomasum
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
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
many plies, grinds food more finely and absorb excess moisture, broad longitudinal folds or leaves resemble the pages in a book, not function in rumination.
Omasum
true/ glandular stomach of ruminants, secretes gastric enzymes and hydrochloric acid.
Abomasum
Muscular tube connecting the stomach to the
cecum and the large intestine.
small intestine
Suspended from the dorsal part of the abdominal cavity by a fold of peritoneum Called ____
great mesentery.
Small intestines 3 parts
Duodenum, Jejunum, Ileum
makes-up 5% of the total length of the small intestine. It has an s-shaped portion which contains the pancreas.
duodenum
makes-up 90% of the total length and has not clear demarcation from other either duodenum or ileum. Forms the mesenteric part of the intestine, and
generally located in the left dorsal position of
the abdominal cavity.
jejunum
makes-up about 4 to 5% of the total length of the intestine. This portion is connected to the cecum and large intestine.
ileum
small intestines glands
Intestinal gland, Duodenal gland, Peyer’s patches
crypt of Lieberkühn or intestinal crypt
Found throughout the small intestine.
Intestinal gland
Crypt of Lieberkühn - Cells:
Goblet cells, Enterocytes, Enteroendocrine cells, Paneth cells, Villi
secrete mucus for lubrication and protection.
Goblet cells
secret water and electrolytes
Enterocytes
secrete hormones
Enteroendocrine cells
secrete antimicrobial peptides
Paneth cells
reabsorbs the water and electrocytes
Villi
Brunner’s glands
Found in the first part of the small intestine;
produce a mucus-rich alkaline secretion.
Duodenal gland
associated with immune system.
Peyer’s patches
Is composed of several organs with distinct
functions.
large intestine
(cul de sac) – is a blind sac situated between the ileum and the great colon.
In herbivores, this organ stores food materials for microbial digestion and fermentation, especially in hindgut fermenters (e.g., horses).
Cecum
is a coiled tubular organ responsible in absorbing water from digested food.
Colon
Colon 3 parts
Ascending colon, transverse colon, descending 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
relatively straight, running caudad on the left
side of the abdomen to the pelvic cavity, where it terminates as the rectum.
Descending colon
terminal part of the intestine and is found in the pelvic cavity. Serves as a temporary storage for feces.
rectum
terminal part of the alimentary
tract, continuous with the skin.
anus
3 important muscles responsible for its function:
Sphincter ani internus, Sphincter ani externus, Retractor ani
circular smooth muscle
Sphincter ani internus
outside the preceding, composed of skeletal
muscle fibers and adhere intimately to the skin surrounding the margin of the anus.
Sphincter ani externus
retracts the partial prolapse that the anus undergoes during defecation.
Retractor ani
The following are structures associated with
the abdominal visceral muscles:
Peritoneal structures
tethers the liver to the ventral midline.
Falciform ligament
spanning between the left kidney and spleen.
Renosplenic (nephrosplenic) ligament
connecting the liver and proximal duodenum.
Hepatoduodenal ligament
parts of the peritoneum connecting the stomach with other structures.
Omentum
extending from the lesser curvature of the
stomach to the liver.
Lesser omentum
attached to the greater curvature of the
stomach (and the comparable portion of the ruminant stomach).
Greater omentum
Accessory Digestive Organs
Salivary glands, Pancreas, Liver,
Provide necessary digestive enzymes, a route of excretion of substances which accumulate on the teeth and provide lubricative and cleansing functions.
Salivary glands
3 major types of salivary gland.
Parotid, Mandibular, Sublingual
located ventral to the ear in relation to the
caudal border of the mandible.
Parotid Salivary Gland
located ventral to the parotid, just caudal to the
mandible.
Mandibular 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
There are also minor salivary glands such as:
labial, buccal, lingual, and palatine glands.
produce a watery clear fluid.
Serous Glands
secrete, a viscous material that acts as a protective covering for the surface of mucous membranes.
Mucous Glands
produce both mucous and serous fluids.
Mixed Glands
secretes primarily serous saliva. The mandibular and sublingual salivary glands are mixed glands in domestic farm animals.
Parotid salivary gland
Most minor salivary glands have__
mucous secretions
Is a compound gland, which is irregularly lobulated and lies adjacent to the proximal duodenum (first loop of the duodenum).
Pancreas
producing sodium bicarbonate and digestive enzymes through pancreatic ducts.
Exocrine (acinar) portion
consists of isolated groups of pale-staining cells scattered throughout the gland called the pancreatic
islets (formerly islets of Langerhans).
Endocrine portion
The _____ are responsible in
producing the hormones that pass directly
into the bloodstream most notably glucagon
and insulin, which are the primary regulators
of blood sugar levels.
pancreatic islets
3 major types of cells within the pancreatic islets:
alpha, beta, delta
responsible in producing glucagon, which raises the level of glucose (sugar) in the blood.
alpha cells
responsible in producing insulin for decreasing and utilization of blood glucose by body tissues.
beta cells
responsible in producing somatostatin which inhibits the release of numerous other hormones in the body.
delta cells
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
The blood enters the liver via:
hepatic artery, portal vein, heptic vein
branch of the celiac artery.
hepatic artery
main trunk of the portal system and blood leaves the liver via the:
portal vein
enters the posterior vena cava. The blood leaves the liver through the hepatic vein.
hepatic vein
= The liver’s digestive secretion, bile, leaves
the liver through [hepatic ducts], which join the
[cystic duct] from the gallbladder to form the
[common bile duct], which then passes to
proximal duodenum into the lumen to which it
opens in common with the pancreatic duct on
the major duodenal papilla.
All domestic animals except the _____have
a gallbladder for storage of bile.
horse
The morphologic unit of the liver is the___
a polygonal cylinder of liver cells (the hepatocytes) in the center of which is a central vein at the angles on the periphery.
hepatic lobule
In and around the sinusoids are fixed macrophages, which in this location are called ____
Kupffer cells
3 lobes: right, middle, or central, and left lobes; no gall bladder
equine
Not divided into lobes
bovine
4 lobes: right lateral, right medial, left lateral, and left medial
porcine
5 lobes: left lateral, left central, right central, right lateral, and caudate lobe.
canine
Is the rhythmic, coordinated contraction of
muscles to move ingesta along the GIT.
Peristaltic Movement
There are usually two layers of smooth
muscles:
inner layer is circular and outer layer is longitudinal,
circular muscles contract behind the food mass.
inner layer is circular
muscles contract ahead of food mass.
outer layer is longitudinal
AVIAN
Modification of the ____ into a ____,
the shape of which is adapted to the
foraging behaviors and diet of
individual species.
jaws, beak
AVIAN
The _____ is incompletely fused
resulting in a longitudinal opening
between oral and nasal cavities called
the choanal cleft.
palate
AVIAN
Which provides pepsin, and hydrochloric acid
for enzymatic digestion,
Proventriculus or glandular stomach (first chamber)
AVIAN
Highly keratinized mucosa on the inside, the
cuticle, forms a thick, leathery sheet, which is
removed during processing for human
consumption; has grit
Gizzard or muscular stomach (or ventriculus muscularis)
AVIAN
remnant of the embryonic connection to the yolk sac.
The short ileum terminates at the large
intestine, a point demarcated clearly in
domestic birds by the presence of paired
ceca.
Meckel’s diverticulum
AVIAN
that temporarily holds feces
coprodeum
AVIAN
that has openings for two ureters
Urodeum
that houses the male reproductive organs (or has opening for the female reproductive tract), and has the opening of the bursa of Fabricius.
Proctodeum
= Absorption of water and electrolytes in the
ceca, rectum, and coprodeum contribute to
overall fluid and electrolyte balance
