neural control

• stomach ber 3/min
• Duodenum ber 12/min
• Terminal ileum ber 9/min
• Ber is slow wave contractions, subthreshold
• Enteric pike potentials = calcium influx depolarisation, potassium efflux repolarisation
• Spike potentials 1-10/sec
• Depolarisation caused by stretch receptors, ach, PSNS, Gastric, cck
• Repolarisation stimulated by adrenaline, noradrenaline, SANS
• Higher slow wave potentials = > frequency of spike potentials
• Ber basic electrical rhythm
• Syncytium bc gap junctions
• Ca binds calmodulin = triggers smooth muscle contraction
• Inc. Contractility = kinases dec. Contractility = phosphatases. Phosphatases Inc. By NO, guanylate cyclase, gtp, cAMP, protein kinaesthetic G
• Sildenafil, tadenafil, vardenafil agonists for phosphatases, git relaxation
• Minoxidil and diazoxide open k+ channels (repolarisation easier)
• Tonic contraction = continuous
• Psns excites plexuses. Sns inhibits plexuses.
• Psns. Vagus. Synapse at target. Sns. Greater splanchnic t5-9. Lesser splanchnic t10-11. Least splanchnic t12
• Greater splanchnic. Foregathered. Coeliac ganglia
• Lesser splanchnic. Superior mesenteric ganglia/artery. Midgut
• Least splanchnic. Inferior mesenteric ganglia/artery. Hindgut
• Chyme is transferred to the duodenum with the aid of the migrating myoelectric complex (MMC). This is characterised by 10-20 minutes of intense antral contractions every 1-2 hours during fasting clear particles from the stomach
• peristaltic rush = powerful peristalsis through ANS and intrinsic control of myenteric plexus during infectious diarrhoea
• defecation = Faeces entering the rectum stretches the walls and stimulates the myenteric plexus to initiate peristaltic contractions in the descending colon downward. The myenteric plexus relaxes the internal sphincter. If the external sphincter is voluntarily relaxed, defaecation occurs. This is augmented by parasympathetic activity.
• gastrin, cholecystokinin, cerulein and clonin all have a sulfate group attached to tyrosine
• Gastrin

  Produced by G cell in the mucosal gland of the gastric

  antrum

  Can also be found in the fetal pancreatic islet,

  hypothalamus, medulla oblongota and vagus nerve