GI Motility 4 Flashcards
What 4 physiological processes is the GI system involved in?
- Motility
- Secretion
- Digestion
- Absorption
Which nervous system controls the GI system?
Enteric nervous system
What are the 4 accessory glands to the GI system?
- Salivary glands
- Liver
- Gallbladder
- Pancreas
What type of muscle makes up sphincters?
Smooth muscle
What are the layers of the gut wall (lumen to abdominal cavity)?
- Mucosa
- Submucose
- Muscular externa
- Serosa
Which nerve plexus regulates gut motility?
Myenteric nerve plexus (Auerbach’s)
Which nerve plexus regulates blood flow and secretion?
Submucosal nerve plexus (Meissner’s)
What does the myenteric nerve plexus innervate?
The longitudinal and circular smooth muscle layers
What does the submucosal nerve plexus innervate?
- Glandular epithelium
- Intestinal endocrine cells
- Submucosal blood vessels
Innervations of the Vagus nerve.
- Oesophagus
- Stomach
- Small intestine
- Liver
- Pancreas
- Caecum
- Appendix
- Ascending colon
- Transverse colon
What is the caecum?
A pouch that lies in between the small intestine (ileum) and the large intestine (ascending colon).
What does sympathetic and parasympathetic activity do to gut motility and secretion?
- Sympathetic activity inhibits gut motility and secretion.
- Parasympathetic activity stimulates gut motility and secretion.
Where is the myenteric nerve plexus located?
Between the longitudinal and circular muscle layers.
Where is the submucosal nerve plexus located?
Between the circular muscle and submucosal layer.
What is Hirschsprung’s disease?
Congenital absence of the myenteric plexus, leading to a lack of peristalsis, spasms and constipation.
What are the 3 types of GI movement?
- Segmentation
- Peristalsis
- Tonic contraction
What is the migrating motor complex?
Strong contractions that pass down down the distal stomach and small intestine every 90 minutes.
What is paralytic ileus?
Cessation of gut motility that is mainly caused by abdominal surgery (can also be caused by infection, inflammation, electrolyte abnormalities and drug ingestion).
What is deglutition?
Swallowing
What is mastication?
Chewing
What part of swallowing is under voluntary control?
- The formation of a blue through mastication
- The propelling of the bolus to the oropharynx when the tongues moves up against the hard palate
How is involuntary deglutition initiated?
1) Bolus stimulates mechanoreceptors in the pharynx
2) Glossopharyngeal afferent impulses are sent to the swallowing centre
How does the body ensure that the bolus only travels down the oesophagus?
- Soft palate elevates and blocks off the nasopharynx
- Respiration is inhibited
- Larynx rises so that the epiglottis covers the trachea.
Which efferent nerve co-ordinates deglutition?
Vagus nerve which stimulates peristalsis to commence (starting from the pharynx).
