(11) Digestive System Flashcards
Its Functions:
• Prehension and mastication
• Provides an alternate or supplemental airway
• Facilitates intra- and interspecific communication (by facial posturing), defense and vocalization
MOUTH
• The wide gape of it is related to the dog’s role as predator
• The ability to open it wide permits the use of the teeth in securing prey
• Also permits rapid consumption of large pieces of food without extensive mastication
• Elongated in all but brachycephalic breeds
MOUTH
• In anatomic term includes only the opening between the lips into the vestibule of the oral cavity
MOUTH (ORAL FISSURE)
• The space extending from the lips to the pharynx, bounded laterally by the cheeks
• Divided into: 1. vestibule, 2. oral cavity proper
• Contains the salivary glands , teeth and tongue
• Teeth separate the outer vestibule from the central oral cavity proper
ORAL CAVITY
ORAL CAVITY Divided into:
- vestibule, 2. oral cavity proper
It separate the outer vestibule from the central oral cavity proper
Teeth
• The space external to the teeth and gums, and internal to the lips and cheeks
• bounded laterally by the cheeks and lips, medially by the teeth and gums that contains the openings of certain salivary glands
ORAL VESTIBULE
the space between the incisors and the lips
Labial vestibule
the space between the cheek teeth and the cheeks
Buccal vestibule
These two open into the dorsocaudal part of the vestibule
parotid and zygomatic salivary ducts
It is located opposite the caudal part of the superior fourth premolar tooth, approximately 5 mm from the fornix of the vestibule parotid duct opens through the cheek
Parotid papilla
• The region containing the teeth, tongue and openings of certain salivary glands
ORAL CAVITY PROPER
Identify the dorsal boundaries of the oral cavity proper.
Hard palate, small part soft palate
Identify the ventral boundaries of the oral cavity proper.
Tongue and reflected mucosa
Identify the lateral and rostral boundaries of the oral cavity proper.
Dental arches and teeth
Identify the caudal boundaries of the oral cavity proper.
Palatoglossal arches
the major sublingual and mandibular salivary glands open rostrally ventral to the body of the tongue on the caruncles
Sublingual caruncles
formed by the underlying mandibular and major sublingual ducts and a variable number of lobules of the polystomatic portion of the sublingual gland
Sublingual fold
a rounded eminence that extends caudally to blend with the first transverse ridge formed of the mucosa covering the hard palate, just caudal to the superior central incisor teeth; behind the incisor teeth where the incisive ducts open, ducts lead to vomeronasal organ
Incisive papilla
the spaces between the teeth
Interdental spaces
form the rostral and most of the lateral external boundaries of the vestibule; has philtrum; superior and inferior lips with tactile hairs
Lips
the median cleft of the upper lip
Philtrum
oral commisure; where upper and lower lips unite
Angle of the mouth
form the caudal portion of the lateral walls of the vestibular
cavity; buccinator muscle; support, send food from outer vestibule into mouth cavity proper
Cheeks
gingiva; the oral mucosa over the jaws, enclosing the necks of the teeth
Gums
roof of the mouth cavity proper; partly bony, partly membranous partition separating the respiratory and the digestive passages of the head
Palate
bony shelf formed by the palatine processes of the incisive, maxillary, and palatine bones; covered by ridged mucosa
Hard palate (palatum durum)
six to ten paired elevations crossing the hard palate transversely
Palatine ridges
caudal continuation of the hard palate, composed of small muscles, salivary glands, and connective tissue, separates the oral and nasal cavities
Soft palate (velum palatinum)
serves a part of the boundary between the nasopharynx and the laryngopharynx
palatopharyngeal arch (arcus palatopharyngeus)
serves as part of the boundary between the oral cavity and the oral pharynx
palatoglossal arch (arcus palatoglossus)
the main arteries to the hard palate
major palatine arteries (aa. Palatinae majores)
Main arteries to the soft palate are the, aided by the ascending pharyngeal (a. pharyngea ascendens) and the major palatine
minor palatine arteries (aa. palatinae minores)
• are highly specialized structures that serve for the procuring, cutting, and crushing of food as well as for social interaction.
• Perform the principal function of mastication but also aid in food gathering (prehension) and are formidable weapons in some species
TEETH
visible part of the tooth, encased in enamel
crown
embedded in the gum, encased in cement
root
between the root and the crown
neck
row of teeth, usually refers to superior (upper/maxillary) or inferior (lower/mandibular) dental arcade
Dental arcade/arches
tooth socket
Alveolus
specialized connective tissue that connects the tooth to the socket
Periodontal ligament
The first set that is fully erupted and functional early in the second month after birth; is replaced by a second, stronger, permanent set of teeth
Temporary dentition (milk or deciduous)
teeth are differently developed in different regions of the mouth for specific functions
heterodont
dental formula - arranged as
I/I - C/C - P/P - M/M
• low crowned teeth
• have crown, neck, and root
• suited to a softer diet with less wear
• stop growing
brachydont
• some of the crown of the tooth is below the gumline, extruded later with attrition of the masticatory surface
• characterized by continual eruption
• equine and bovine are examples (except ruminant incisors and canines are brachydontal)
hypsodont
forms the body of the tooth
Dentin
is soft tissue surrounded by dentine, composed of connective tissue, richly vascularized and innervated; contained within the central pulp cavity of the tooth
Pulp
Surface faces the tongue
Lingual surface
Surface faces the lip or cheek (vestibule)
Vestibular surface (labial/buccal)
the surface adjacent to the next tooth in the dental arch (all are distal or mesial)
Contact surface
the contact surface adjacent to the next caudal or lateral tooth
Distal surface
the contact surface adjacent to the next rostral or medial tooth
Mesial surface
surface that faces the ipsilateral opposite superior or inferior dental arch; masticatory or chewing surface
Occlusal surface
Direction toward the crown
Coronal
Direction toward the apex of the root
Apical
small, peg like, most rostral teeth adapted to cutting
Incisor (I)
robust, long, pointed and slightly curves teeth that are adapted to piercing and grasping prey for food
Canines (C)
“cheek teeth”
Premolars and molars
irregular, often have several cusps ( projections of the crown of the tooth); smaller than molars, adapted to assist the canine teeth with grasping
Premolars (P)
“carnassial or sectorial teeth” of the upper jaw; largest teeth of the upper arcade
Upper 4th premolar
irregular teeth with cusps, broader than premolars, used primarily for crushing, present only in adults; variable in size and form; adapted to chewing or shearing
Molars (M)
DENTAL FORMULA
• Temporary : ?
(I3/3 C1/1 P3/3 M0/0)2 = 28
DENTAL FORMULA
• Permanent : ?
(I3/3 C1/1 P4/4 M2/3)2 = 42
• a system for numbering each tooth in the mouth
• each tooth is assigned a 3-digit number
Modified Triadan System
Quadrant: right upper/maxillary
Quadrant number: ?
100
Quadrant: left upper/maxillary
Quadrant number: ?
200
Quadrant: left lower/mandibular
Quadrant number: ?
300
Quadrant: right lower/mandibular
Quadrant number: ?
400
• A term used to designate the supporting tissues of the teeth.
PERIODONTIUM
This so-called “ ? ” is filled by blood vessels, lymphatics, and
nerves as well as collagenous and elastic connective tissue fibers and cells.
space
• Surround the teeth and are composed of dense fibrous tissue covered by smooth, richly vascularized mucosae.
• They bleed readily and heal quickly.
• It is thick around the necks of the teeth and extend down into the alveoli to be continuous with the alveolar periosteum.
• The labial surface of it is continuous with the mucosa of the vestibule.
• Internally it blend with the floor of the oral cavity proper and the hard palate.
• In those breeds with pigmented mucosae the it is likewise pigmented
Gums
• The muscular organ filling the oral cavity; forms the floor of the oral cavity
TONGUE
Part of tongue, widest most caudal position; attached to the basihyoid bone of the hyoid apparatus; lies within the oropharynx
root
main part of tongue, attached to the floor of the oral cavity by a mucosal fold called the frenulum
body
tip of tongue, free or unattached
apex
• important prehensile organ, also used by dog to dissipate heat
• involved with movement of ingesta within the mouth
TONGUE
Only dogs has a ? - a fibrous septum (rodlike, flexible) that forms the median groove on the dorsum of the tongue, act as the stretch receptor of the tongue
lyssa (lytta)
covers the tongue’s dorsum on the rostral 2/3; smallest and most numerous; thorn shaped structure serving the mechanical function of directing food caudally
Filiform
mushroom-shaped on the rostral 2/3 of tongue; gustatory
Fungiform papillae
largest and least numerous; circled by a cleft filled with taste buds rostral to the root (caudal third) of the tongue; with serous gustatory glands or von Ebner’s gland
Vallate (circumvallate) papillae
series of leaf-shaped ridges separated by furrows on lateral border of tongue; gustatory
Foliate
cone-shaped papillae located on the caudal 1/3 of the tongues dorsum; mechanical function
Conical and lenticular papillae
this pappilae can only be found in newborn puppies that function in suckling, helping to prevent milk from spilling, aid in sealing the lips around the nipple for suction; disappears when diet changes from milk to solid; mechanical and tactile
Marginal papillae
the sense of it to rostral two thirds of the tongue is carried over to the facial nerve
Taste (special sense)
This innervations of the tongue carried over the lingual branch of the mandibular nerve
Sensation (pain, temperature and tactile)
This innervation of the tongue is via the hypoglossal nerve
Motor innervation
muscular bundles running in diverse directions to form the bulk of the tongue; cause subtle changes in the shape of the tongue during swallowing, chewing and vocalization
Intrinsic muscles
Muscle that anchor the tongue to the skeleton
Extrinsic muscles
• This gland resembles letter “V”, surrounds the base of the ear
• molded around the ventral part of the auricular cartilage
• Parotid duct crosses the surface of the cheek and masseter muscle to enter the vestibule of the mouth next to the upper 4th premolar tooth
• Predominantly serous secretion
Parotid gland
• this gland is round or oval situated between lingoufacial and maxillary veins
• smaller than parotid
• found ventral to the ear medial to the angle of the mandible
• drains by a single duct
• duct runs deep to the mandible, lateral to the root of the tongue
• enters the oral cavity at the sublingual caruncle found on the floor of the mouth
• Mixed secretion
Mandibular glands
• Gland under the tongue having polystomatic and monostomatic part
• can be attached to the rostral edge of the mandibular gland
• duct runs with the mandibular duct
• Mixed secretions
Sublingual gland
• ventral to the eye
• deep to zygomatic arch
Zygomatic gland
• A part of pharynx between the soft palate and the epiglottis, it contains tonsillar tissue
OROPHARYNX
• lymph nodules; diffuse aggregates of lymphoid tissue
• Found on the dorsolateral oral mucosa of oropharynx
• Guard against passage of infectious agents to deeper parts of the digestive and respiratory systems
• Like a lymph node, with no capsule or afferent ducts
• Entrance usually in the form of crypts
Tonsils
• muscular tube, begins dorsal to the cricoid cartilage of the larynx
• carries food from pharynx to stomach
ESOPHAGUS
• Lies in the left cranial quadrant of the abdomen, within the rib cage and caudal to the liver
• Functions: storage, acidification and manipulation of the ingesta for periodic passage to the intestines
Stomach
entrance of the esophagus into the stomach
Cardia
a blind region or dome rising above the cardia, positioned farthest left of the midline
Fundus
largest portion of the stomach between the fundus and the pyloric part
Body
caudal third of the stomach
Pyloric part
dilated portion of the pyloric part of the stomach, between the body and the pylorus
Pyloric antrum
distal opening of the stomach into the small intestine; controlled by the pyloric sphincter
Pylorus
caudal convex border, the outside of the “C” shape of the stomach
Greater curvature
cranial concave border, the inside of the “C” shape of the stomach
Lesser curvature
a double fold of peritoneum; attaches the spleen to the greater curvature of the stomach; first structure observed on ventral incision
Greater omentum
space between the two folds of the greater omentum, opening into which is called the epiploic foramen
Omental bursa
attaches the porta of the liver to the lesser curvature of the stomach
Lesser omentum
• this ligament fixes the cardia to the region of the esophageal hiatus in the diaphragm
Gastro-phrenic ligament
• Connects the lesser curvature and pylorus to the hilus of the liver
Gastro-hepatic ligament
• Forms part of the greater curvature, attaches the spleen to the greater curvature of the stomach
Gastro-splenic ligament
• The principal site of digestion and absorption
SMALL INTESTINE
Small intestine are divided into (proximal to distal):
duodenum, jejunum, and ileum
is most extensive (longest) part of small intestine
jejunum
• A small-bore muscular tube with a smooth external surface of the small intestine
• Lies to the right of the midline and is held close to the dorsal
abdominal wall by its short mesentery
Duodenum
• The short terminal portion, positioned near the dorsal body wall just lateral to the ascending duodenum
Ileum
• A blind-ended pouch (diverticulum); projects from the junction of the ileum and large intestine
• Positioned right of the midline in the cranial abdomen, close to the dorsal body wall (in the region of the transverse process of vertebrae L2-L4) and dorsal to the jejunal loops
• consists of a base, body, and apex
CECUM
• The major part of the large intestines, larger in diameter than the S.I.
COLON
modified in all species; on right side ( colon )
ascending colon
right to left; cranial to the root of the mesentery ( colon )
transverse colon
the longest segment of the large intestine; continuous to rectum on the left side
descending colon
• The large intestine within the pelvic cavity, extending from the descending colon to the anal canal
RECTUM
the short termination of the alimentary canal, opening to the exterior as the anus
Anal canal
the external opening of the intestine
Anus
• Usually referred to as anal sacs, consist of two sinuses with one on each side of the anal canal
• frequently become enlarged, or they may become abscessed and painful, causing constipation
• functions for territorial scent marking as in wolves
PARANAL SINUS
• The region of the pelvic outlet.
• It includes the anal and urogenital regions
PERINEUM
• a glandular organ similar in appearance to a salivary gland
• v-shaped; right lobe associated with the mesoduodenum, left lobe associated with the caudal surface of the stomach near the spleen
• functions as both an endocrine and an exocrine gland
PANCREAS
largest part of pancreas, produces enzymes essential for the
digestion of carbohydrates, fats and proteins
Exocrine gland
produces insulin and glucagon essential in regulating the sugar content of blood ( pancreas )
Endocrine gland
more cranial usually smaller of the two ducts of pancreas opens into the cranial part of descending duodenum on major duodenal papilla; occasionally absent.
Pancreatic duct
largest duct of pancreas, caudally positioned main conduit of the gland in dogs, opens on the minor duodenal papilla
Accessory pancreatic duct
• The largest gland of the body
• Function:
• Has both exocrine and endocrine functions
• Also play a role in the metabolism of food and the detoxification of numerous substances
• Positioned immediately caudal to the diaphragm; attached to the diaphragm by the triangular, coronary, and possibly the falciform ligaments
• covered with peritoneum except by the porta (portion that transmits the hepatic vessels, nerves and bile duct)
• divided by fissures into lobes
LIVER
• With renal impression ( lobe of a lung )
Right lateral lobe
• Lies along the midline
• Gallbladder lies bet
• Falciform ligament lies bet. The quadrate and left medial lobe
Quadrate lobe
This lobe of liver has two processes
Caudate lobe
largest part, forms the majority of the renal impression ( liver )
Caudate process
• “U”-shaped attachment on the diaphragmatic surface of the liver; provides the only attachment of the liver to any wall of the abdomen
Coronary ligament
• Thin, transparent fold of peritoneum at the right and left termination of the coronary ligament
Triangular ligament (R and L)
• This ligament extends between the liver and the diaphragm and ventral body wall caudally to the umbilicus
Falciform ligament
• Contained in the free border of the falciform ligament; a vestige of the umbilical vein of the fetus
Round ligament
• Doubled layer of the peritoneum that extends between the renal fossa of the liver and the right kidney ( ligament )
Hepatorenal ligament
• Positioned approximately at the level of the 8th intercostal space
• stores bile produced by the liver
• released as needed into the cystic (bile) duct to the cranial duodenal papillae in the proximal portion of the small intestine
GALLBLADDER
This duct carries bile from the gallbladder to the duodenum; also receives the hepatic duct from the hepatic parenchyma
Cystic duct
3-5 ducts receiving bile from multiple lobes and carrying it to the cystic duct
Hepatic ducts
the continuation of cystic duct following entrance of the last hepatic duct; opens on major duodenal papilla
Common bile duct
