Digestive Organs

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Digestive Organs
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Organs

• Include organs which are concerned with
• mastication
• salivation

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• swallowing
• deglutition
• digestion
• absorption
• initial storage of nutrients
• elimination

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• Therefore include
• Mouth
• ? lips
• ? cheek
• ? palate
• ? teeth- males have 40 teeth, females 36 normally
• ? labial and buccal glands

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• Pharynx
• Alimentary canal
• Several accessory glands
• ? parotid
• ? mandibular
• ? sublingual

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• Liver
• Pancreas
• Alimentary canal begins at esophagus and
  terminates at the anus
• G.I. tract begins at the stomach- ends at the
  anus.

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Esophagus

• The esophagus extends from the laryngo-pharynx to
  cardia of the stomach. Composed of cervical,
  thoracic, and short abdominal part.

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• Esophagus describes different relationships to
  surrounding structures.
• The muscular coat (tunica muscularis) of the
  esophagus consists of striated muscle (voluntary)
  only in cranial 2/3.

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Stomach

• approximately the size of a large man's stomach
  (2-4 gallons). lined by non glandular mucosa
  (stratified squamous epithelium) and glandular
  mucosa (simple columnar epithelium).

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• Histologically, stomach composed of 2 parts
  "proventriculas' and glandular part separated by
  margo plicatus.
• Proventricullus is where bot larvae attach.

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Vomiting

• Horse cannot vomit because
• 1. stomach not palpable through abdominal wall
• 2. cardiac sphincter too strong/ tight

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• 3. esophagus enters cardia more obliquely at
  acute angle.
• 4. muscular coat of caudal 1/3 of esophagus
  consists of smooth muscle
• 5. Stomach lies entirely within the intrathoracic
  part of abdominal cavity. No abdominal press.

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Pathologies

• Diseases of stomach and intestines include
• ? vomiting
• ? indigestion
• ? gastritis

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• gastric typany
• ? rupture of the stomach
• ? gastric dilation
• ? gastric ulcers
• ? colic

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• invagination or intussection
• ? enteritis
• ? superpurgatin
• ? constipation
• ? stricture
• ? sand colic
• ? peritonitis

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Small intestine

• Primary site of digestion occurs in 1st 3rd of
  small intestine-known as the duodenum. Most
  pancreatic enzymes enter the digestive tract
  here. 2nd and 3rd portions known as the ileum
  and jejunum. Most important function is
  breakdown of non cellulose CHO and proteins, but
  some fat digestion occurs here as well.

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Cecum

• The first third of the horses large intestine is
  known as the cecum. Digestion of cellulose takes
  place here. The cecum of a horse has a large
  number of microflora which are able to break the
  cellulose chain, allowing the horse to digest
  plant material that you or I are unable to digest
  at all. A similar mechanism exists in the rabbit
  and in the adult pig- though to a lesser degree.
  The horse is able to sustain itself on cellulose
  based plant life entirely-although not as
  efficiently as a ruminant animal.

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Colon and rectum

• The horses colon and rectum are large, act to
  absorb some nutrients broken down in the cecum
  and also to absorb water that has been secreted
  into the tract throughout the upper G.I. Fecal
  balls are formed here.