Digestive System Flashcards
Teeth
Performs the principal function of mastication (chewing), but also in food gathering (prehension) and are used as weapons in some species
Salivary Glands
The extramural glands (outside the digestive system), which empty into the digestive system via ducts, classified by size, duct length and secretions (can be serous, mucous or both)
Palate
The roof of the oral cavity composed of the rostral bony part (hard palate) and a caudal musculomembranous part (soft palate), acts to separate the respiratory and digestive passages in the head.
Pharynx
Acts as the common passageway for the digestive and respiratory systems, connects the nasal and oral passageways with the trachea and esophagus serving to direct the intake of food and air into proper channels
Esophagus
Muscular tube that transports food fro the oral cavity and the pharynx down the neck and through the thorax to the stomach. Is at first dorsal to the trachea and then shifts to the left of the trachea.
Stomach (Simple)
- Breaks down food into chyme, food enters the stomach through the esophagus, glandular mucosa in the gastric folds produce digestive enzymes. Food then moves to the pyloric atrium and through the pylorus where it enters the duodenum
- Lined by glandular epithelium, non-glandular epithelium or both
Ruminant Stomach (Complex)
- 4 chambered stomach: rumen, reticulum, omasum and abomasum
- rumen: the largest compartment, divided into sacs, fermentation vat for micro-organisms to break down cellulose into metabolizable components, fills the abdomens left side
- reticulum: the most cranial compartment, located on the median plane against the diaphragm, honeycomb appearance
- omasum: the spherical compartment caudal to the reticulum, book/page like appearance of muscular laminae
- abomasum: the elongated “true stomach” lined by glandular tissue/mucosa, located on the right side in contact with the ventral abdominal wall
Small Intestine
Principal site of digestion and absorption, runs from the pylorus to the large intestine. Consists of 3 parts: the relatively fixed and short duodenum, the freely moveable long middle portion called the jejunum (mesentry allows great range of motion), and the short terminal part called the ileum which empties into the large intestine
Large Intestine
The cecum, colon, rectum and anal canal, extends from the ileum to the anus and functions to dehydrate fecal contents by absorbing water
Horse Large Intestine- Cecum
Huge, comma shaped structure occupying much of the right abdominal cavity, consists of the base (the bulbous beginning of the cecum ), the body (the continuation of the base cranially along the right wall and floor of the abdominal cavity), the apex (the tapered end of the cecum on the floor of the abdominal cavity, the ventral colon wraps around it)
Horse Large Intestine- Pelvic Flexure
The connection of the left ventral and left dorsal colons in the left paralumbar fossa, near the pelvic inlet
Horse Large Intestine- Right and Left Dorsal Colon
- left dorsal colon is a continuation of the pelvic flexure cranially on top of the left ventral colon and against the left abdominal wall
- right dorsal colon is the greatly expanded continuation of the diaphragmatic flexure caudally to the transverse colon
Rectum
The large intestine within the pelvic cavity, extending from the descending colon to the anal canal
Liver
- The largest gland in the body, divided into four lobes and sub-lobes. Filters blood and produces bile
- located against the diaphragm, encloses the right kidney
Gallbladder
The sac storing and concentrating bile, located between the quadrate and medial lobes of the liver, not present in the horse
