Gastrointestinal Tract Med Term

Pharynx Common passageway for air and food. Commonly referred to as the throat.

The Esophagus Muscular tube from the pharynx through the diaphragm to the stomach Dilates as food passes through, lumen is typically closed otherwise. http://www.medicalvideos.us/videos/1804/

The art of swallowing 3 phases voluntary – passage of food from the mouth to the pharynx. At this point, the larynx is blocked by the epiglottis, so food should only go in the correct direction. Tongue also helps by pressing against the hard palate.   1st involuntary – reflex phase that passes the food from esophagus to the stomach. Respiration is suppressed as to keep food from going into the trachea. 2nd involuntary – muscles contract the food through the cardiac sphincter into the stomach

http://www.youtube.com/watch?v=vBtJ1D3S_p8 http://www.youtube.com/watch?v=wqMCzuIiPaM&feature=related

The Simple Stomach/ Monogastric - 3 main sections: FUNDUS, BODY, PYLORUS

Sphincter Muscles -sphincters are muscles in a ring shape that close an opening when they contract CARDIAC SPHINCTER – located between the esophagus and stomach. Food enters when it relaxes. Sphincter tightens when digestion is taking place. Prevents reflux. PYLORIC SPHINCTER – located between the pylorus and the duodenum. Contracts to prevent stomach contents from escaping during digestion. Relaxes to allow contents to leave stomach and continue to intestines.

LAYERS OF THE INESTINAL WALL Mucosa, Submucosa, Muscle layer, Serosa

CHYME = semifluid contents of stomach after digestion CHYME = semifluid contents of stomach after digestion. Moves through digestive tract via peristalsis.

Ruminant Stomach 4 CHAMBERS: rumen reticulum omasum abomasum Three forechambers to true stomach are called diverticula and help ferment the food.

Terms used in Ruminant Stomach Rumination- Includes regurgitation, remastication, ensalivation, and reswallowing of partially digested food. “Chewing of the cud” Remastication- Rechewing the food. Cud- bolus containing fiber, other food particles, rumen liqud, and flora; regurgitated by ruminants. Fermentation- anaerobic conversion of organic compounds, such as carbohydrates, to simpler compounds, producing energy.

The Reticulum Most cranial chamber and is honeycomb in appearance. Where hardware disease can occur.

The Rumen Also called “the paunch” Large sac extending from the diaphragm to the pelvis, makes up 20% of the animal’s body weight, made up of numerous long papillae. Divided into the ventral and dorsal sac.

The Omasum “book” round, lined with short, blunt papillae in folds that grind roughage before going on to the abomasum

The Abomasum “True stomach” Only glandular portion of the stomach. Secretes digestive enzymes to break down food particles, has a pylorus, opens into small intestines.

Structures of found in the abdomen PERITONEUM – membrane that lines the abdominal cavity; holds viscera in place

OMENTUM – fold of peritoneum overlying organs, esp stomach OMENTUM – fold of peritoneum overlying organs, esp stomach. lace-like in appearance

MESENTERY- peritoneal fold that attaches the intestines to the dorsal abdominal wall

Small Intestine where digestive process is completed Entero- refers to intestines VILLI of the small intestine (threadlike projections that line the mucosa) is where absorption takes place.

Parts of Small Intestine   DUODENUM: - attaches to the end the stomach ; pancreatic and bile ducts empty here; digestion and absorption occur here JEJUNUM: - middle section; held in place by mesentery; vigorous peristaltic wave action ILEUM: - most food absorption takes place here

Food moved through by peristalsis and stimulated by hormone secretin

Large Intestine Fermentation occurs here. Made up of: Cecum pouch that forms the first portion of the large intestines joins with the colon larger in herbivores breaks down fibrous material Colon ascending transverse, descending portions

cecum and colon have HAUSTRA in the rabbit, pig and horse (sacculated bands)

Rectum section of descending colon that dilates to store feces ANUS – termination of the digestive tract. made of both smooth and skeletal muscle   COPROPHAGY-ingestion of fecal material Rabbits

Pancreas elongated gland adjacent to the duodenum EXOCRINE and ENDOCRINE gland -secretes substances with or without using ducts -enzymes are needed for digestion (amylase, lipase), so they empty into the duodenum -also secretes insulin

Liver “hepat” = liver largest gland in the body, an exocrine gland located immediately caudal to diaphragm that is red/brown in color FUNCTIONS: secrete bile for digestion; metabolizes protein, fat, and carbs; destroys/neutralizes toxins; stores iron, glycogen, and vitamins

Gallbladder stores bile from the liver, which is brought to the duodenum during digestion bile is a fluid that aids in the digestion of fat “chole”- means bile RATS and HORSES do not have a gall bladder bile flows continuously from liver to duodenum