Gastrointestinal Tract

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Gastrointestinal Tract

• Med Term

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Pharynx

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

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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/

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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

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• http//www.youtube.com/watch?vvBtJ1D3S_p8
• http//www.youtube.com/watch?vwqMCzuIiPaMfeature
  related

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The Simple Stomach/ Monogastric

• - 3 main sections FUNDUS, BODY, PYLORUS

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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.

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LAYERS OF THE INESTINAL WALL

• Mucosa, Submucosa, Muscle layer, Serosa

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

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Ruminant Stomach

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

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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.

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The Reticulum

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

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The Rumen

• Also called the paunch
• Large sac extending from the diaphragm to the
  pelvis, makes up 20 of the animals body weight,
  made up of numerous long papillae.
• Divided into the ventral and dorsal sac.

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The Omasum

• book
• round, lined with short, blunt papillae in folds
  that grind roughage before going on to the
  abomasum

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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.

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Structures of found in the abdomen

• PERITONEUM membrane that lines the abdominal
  cavity holds viscera in place

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

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

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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.

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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

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• Food moved through by peristalsis and stimulated
  by hormone secretin

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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

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

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• 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

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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

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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

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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

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