What are the 2 patterns of movement in the GI tract
Peristalsis - reflex response -result of wall stretch
segmentation - mixes lumen content
Electrical activity of GI tract
spontaneous rhythmic fluctuation with MP -64 and -45
specialised cells aka interstitial cells of cajal
spike potential→ increase tension→ cause contraction
Depo→ ca2+ influx
Repo→ K+ efflux
stimulated by stretch, ACh, Parasympathetic
3 ways GI motility is regulated
The extrinsic nervous system (Sympathetic)
originate between T5 &L2 of the spinal cord
innervated all of GI tract
Nerve ending secrete mainly NE and epinephrine
Stimulation = inhabits GI activity
The extrinsic nervous system (parasympathetic)
divided into cranial and sacral
cranial PN fibres are almost in the vagus nerves except to mouth and pharyngeal
sacral originates from 2-2 sacral segment of spinal cord
it passes through pelvic nerve to distal half of large intestine
stimulation causes increased activity
ENS (layers of cells)
-Lumen
-Mucosa (epithelium, lamina propria, muscularis mucosa)
-Submucosa (submucosal plexus)
- Muscularis propria (circular muscle, myenteric plexus, longitudinal plexus)
- Serosa
6 main polypeptides of GI
Cholecystokinin
Secretin
GIP
GLP-1
Gastrin
Motilin
CCK
Secretin
GIP
GLP-1
Gastrin
Motilin
3 segments of the Oesophagus
cervical
thoracic
Abdominal
Innervation and muscle types of the oesophagus
Proximal 1/3 → striated:
- innervated by somatic motor neurons of vagus nerve
distal 2/3 → smooth muscle
- innervated by visceral motor neurons of vagus nerve
- synapse with postganglionic neurons
Lower oesophageal sphincter (LOS)
3 phases of swallowing
5 features that make up the anti- reflux barrier
4 aspects of gastric motility
When PC reaches the pyloric sphincter, the sphincter closes tightly→ No further emptying
Chyme not delivered into duodenum is forced backward into the stomach – “retropulsion.”
3 parts of the stomach
Entry of food into duodenum depends on:
Emesis
Motility of the Small intestine (SI)
Regulation of SI