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Motility In The Gi Tract Notes

Medicine Notes > Gastrointestinal (GI) System Notes

This is an extract of our Motility In The Gi Tract document, which we sell as part of our Gastrointestinal (GI) System Notes collection written by the top tier of Bristol University students.

The following is a more accessble plain text extract of the PDF sample above, taken from our Gastrointestinal (GI) System Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Lecture 3 Motility in the GI Tract



Regulation of GI function o Transmitters
? Intrinsic NS

* Excitatory= ACh and Substance P

* Inhibitory= Vasoactive intestinal peptide (VIP) & Nitric Oxide (NO)
? Extrinsic NS

* Parasympathetic= ACh

* Sympathetic= Noradrenaline o Types
? Hormonal regulation

* 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
? Neural regulation


* Enteric nerves

* Act directly on smooth muscle, or endocrine cell A o Phases of GI control
? CEPHALIC phase

* Sight, smell, taste and chewing
? GASTRIC phase

* 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
? Peristaltic movements

* 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
? Reservoir function

* Lower oesophageal sphincter (LES) & pyloric sphincter help function

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