DIGESTIVE SYSTEM Flashcards by Ashley Celestino

is composed of several organs which provide

the key functions for the survival of animals

digestive system

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physical and chemical breakdown of feeds

as they pass through the gastrointestinal tract

digestion

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physical reduction of particle size

Mastication

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act of swallowing

Deglutition

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bringing

of swallowed food up again to the mouth

Regurgitation

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classification of animals
- consume animal
products; such as dogs and cats

carnivores

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classification of animals
- consume plant products; such as
cattle, sheep, goat, and horses

herbivores

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classification of animals
- consume a
combination of plant and animal products; such as humans and pigs

omnivores

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type of digestive system
- simple stomach such as in
birds, dogs, and pigs

monogastric

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type of digestive system
- multi-compartmented stomach, this
was referred to as compound stomach, are cranial fermenters, such as cattle,
goats, and sheep

ruminants

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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

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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

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oral cavity

- referring to the outer part, between the teeth and the lips (labia) and cheeks

the oral vestibule

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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

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part of teeth
- the part that protrudes
above the gum line

crown

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part of teeth

- the part found at the gum line

neck

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part of teeth
- the part
embedded in the tooth socket

root

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teeth according to permanence

- milk tooth; present at birth

temporary teeth

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teeth according to permanence

- persist throughout the life of the animals

adult teeth

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prominent 
transverse folds of 
thick mucous 
membrane 
covering the hard 
palate

palatine rugae

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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

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teeth according to function
- cutting teeth –
nippers

Incisors

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teeth according to function
- tearing or seizing
teeth – holding teeth

Canines

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teeth according to function

- grinding or shearing teeth

Premolars and Molars

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``` 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