Organ Motility

Organ Motility

1. Stomach

   • Structure
     • Layers
       • Muscularis Externa
         • Outer Longitudinal
       • Submucosa
         • Blood vessels, lymph
       • Mucosa
         • Rugae
   • Functions
     • Reservoir
       • Receptive relaxation
     • Smaller size, mix gastric secrete
     • Empty duodenum controlled rate
   • Innervation
     • Extrinsic
       • Para
         • Stimulate motile, secrete
       • Symp
         • inhibit
     • Enteric
       • Myenteric Plexus
         • Para - Vagus
         • Symp - Coeliac Ganglion
     • Sensory afferent
       • Pa, Distension, pH, pain
       • % receptors, ENS
       • Centrally: Vagus, Splanchnic
   • Motility Coordination
     • Receptive Relax
       • Orad thin
         • lower oeso distend -> induice lower oeso sphincter, orad relax
           • < Pa, > vol. (1.5 litres)
     • Vasovagal Reflex (Vagus)
       • Afferent
         • Mechanoreceptors to CNS
           • chewing, oeso n stomach distend
       • Efferent
         • orad relax
         • VIP from postganglionic peptidergic vagal neurones
     • Mix
       • Fundus, Body muscle thin
         • Weak contract; layers contents -> density
       • Caudad thick
         • Mix, propel to dudenum
         • Contract waves start mid body, stronger toward pylorus
     • Movement Pattern
       • Propulsion: Toward pylorus
       • Grinding: Antrum churn
         • Smaller
       • Retropulsion
         • Bolus push back proximal stomach
           • Further mix; smaller
           • Any solid
           • X overload, protect small intestine (HCl)
     • Slow wave
       • 3-5/ min
       • Para, gastrin, motilin > AP frequency
       • Symp, secretin < AP rate
     • Fasting Activity
       • Periodic Gastric contract
         • Migrating Myoelectric Complexes (MMCs)
           • Motilin from endothelial cells mediate
           • 90 min intervals
           • Clear stomach residue previous meal
     • Gastric Emptying
       • After meal
         • 1,5L solid, liquid, gastric secrete
         • 3h empty
           • Rate
             • Neutralise H+ in duodenum
             • enuf time digest, absorb
             • Ensure stable microbiota
               • pH
               • Flushed
       • Physical factors
         • L > Solid
       • Saline > Acid > Oleate
         • Acid > neutralise
         • Oleate = fatty; fat digest complicated, slower

2. Small Intestine

3. Large intestine

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