Introduction%20and%20Physiological%20anatomy%20of%20Gastro%20Intestinal%20tract

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Introduction and Physiological anatomy of Gastro
Intestinal tract

• Every cell of living system needs energy
• Unicellular organisms
• Exists in the sea of nutrients
• Can satisfy their nutritional need just by
• Proteins present at the cell membrane

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Multi cellular organisms

• In multi cellular organisms, a groups of cells
  converted to a tissue , to perform specific
  function
• A number of systems are evolved in vertebrates
  including humans
• To provide nutrients to all the systems The
  Gastro intestinal tract is accounted for
  extraction of nutrients from the food

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The Food

• The most of the food we eat are macromolecules ,
  it can not cross the cell membrane easily
• so it must be converted to monomers
• Gastrointestinal tract is to make the food in
  absorbable form by help of chewing and mixing
  with various enzymes in mouth to small intestine

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Digestive system
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Components of GIT
Various parts Glands includes
Oral Cavity Salivary glands
Oesophagus Gastric glands
Stomach Pancreas
Duodenum Jejunum Liver and biliary system
Ileum Intestinal glands
Jejunum Endocrine glands
Cecum Enteric nervous system
Colon Circular smooth muscles
Rectum and anal canal Longitudinal muscles
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Structure of wall of the GIT
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Structure of wall of the GIT
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Structure of intestinal villi
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Salivary functions and its regulation

• Saliva is the mixed glandular secretion which
  constantly bathes the teeth and the oral mucosa
• First secretion encounter the food
• It is vital for oral health
• It is constituted by the secretions of the three
  paired major salivary glands
• Parotid, sub mandibular and sublingual
• It also contains the secretions of the minor
  salivary glands

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Structure of salivary Glands
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Parotid gland

• Parotid Is large accounts for 50 sec. of saliva
  (when stimulated)
• Situated in front of ear behind the ramus of
  mandible
• Gland drain in to oral cavity opposite to second
  molar tooth
• Secretions are basically serous

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Structure of sub mandibular and sub lingual gland
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Submandibular and sub lingual gland

• The submandibular gland is variable in size being
  about half the size of the parotid
• lies above the mylohyoid in the floor of the
  mouth.
• It opens into the floor of the mouth underneath
  the anterior part of the tongue
• The sublingual is the smallest of the paired
  major salivary glands,
• It is situated in the floor of the mouth beneath
  the sublingual folds of mucous membrane.

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Structure of salivary gland
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Composition of saliva

• Water 99.55 solid 0.45
• pH 7.04
• Na, K, Ca, Mg, Cl, HCO3- and phosphate
• Organic substances includes
• IgA, Lysozymes, albumin, glucose, lactate, urea
  and ammonia etc.
• Normal salivary flow rates are 0.3-0.4 ml/min
  when unstimulated and 1-1.5 litre/day when
  stimulated
• Approximately 0.5 0.6 litres of saliva is
  secreted perday

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Functions of saliva

• Initiate the digestion of starch
• Protects oral cavity (IgA and lysozymes)
• Provide lubrication for food to make bolus
• Facilitate the taste
• When salivary flow is reduced, dryness of the
  mouth occurs and information from osmoreceptors
  are translated to increase the water intake
• Helps in speaking, swallowing, chewing
• Buffer the gastric secretions reflux in to the
  oesophagus

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Control of salivary secretionBasically
controlled by parasympathetic, sympathetic
stimulation causes proteinaceous secretion
without affecting the volume
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Xerostomia (salivary flowlt 0.2 ml/min)

• The presence of saliva is vital to the
  maintenance of healthy hard (teeth) and soft
  (mucosa) oral tissues.
• Severe reduction of salivary output results in a
  rapid deterioration in oral health
• Patients suffering from dry mouth can experience
  difficulty with eating, swallowing, speech, the
  wearing of dentures, trauma to and ulceration of
  the oral mucosa, taste alteration, poor oral
  hygiene, a burning sensation of the mucosa,
• oral infections including Candida and rapidly
  progressing dental caries
• After radio therapy, old age and multidrug
  therapy