Motility In The Gi Tract Notes
This is a sample of our (approximately) 3 page long Motility In The Gi Tract notes, which we sell as part of the Gastrointestinal (GI) System Notes collection, a 1st (70-80%) package written at Bristol University in 2012 that contains (approximately) 57 pages of notes across 19 different documents.
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Motility In The Gi Tract Revision
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Lecture 3 Motility in the GI Tract
Regulation of GI function o Transmitters
• Excitatory= ACh and Substance P
• Inhibitory= Vasoactive intestinal peptide (VIP) & Nitric Oxide (NO)
• Parasympathetic= ACh
• Sympathetic= Noradrenaline o Types
• Endocrine cell A
1. Circulating hormones (Endocrine)
2. Via blood
3. Act on secretory cells or even paracrine cells
• Endocrine cell B
1. Paracrine (locally) act on secretory cells
• Enteric nerves
• Act directly on smooth muscle, or endocrine cell A o Phases of GI control
• Sight, smell, taste and chewing
• Distension, acidity etc.
• Distension, acidity, osmolarity etc. Musculature of GI tract o Motor activity of GI performs 3 functions
Non-propulsive or Segmentation movements
• "Churning" to promote digestion
• Most frequent type of movement in small intestine
• Rhythmic contraction and relaxation of circular muscle layer
• Mixes chime & brings fresh chime into contact with mucosal surface
• Relatively low frequency
• Progressive contraction of successive sections circular muscle layer
• Propel chime short distance, allows time for digestion/absorption
• Contraction behind & relaxation in front of bolus of food
• Lower oesophageal sphincter (LES) & pyloric sphincter help function
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