Purpose of the gut Flashcards
What are the broad functions of the mouth?
Mechanical disruption (Physical breakdown of food)
Initial digestive enzymes released in saliva
Infection control
What are the broad functions of the oesophagus?
Rapid transport of bolus to stomach through thorax.
What are the broad functions of the stomach?
Storage facility Acid production - breakdown stuff and increase SA Chemical and physical breakdown Infection control Secrete intrinsic factor.
What are the broad functions of the duodenum?
Neutralisation / osmotic stabilisation of chyme -HCO3 rich secretions
Digestion wrapping up - pancreas secretions, bile
What are the broad functions of the Jejunum and Ilium?
Final digestion Nutrient absorption - mainly jejunum Water and electrolyte absorption - mainly ileum Bile recirculation - ileum B12 absorption - terminal ileum
What are the broad functions of the large bowel?
Final water absorption
Temporary storage
Final electrolyte absorption - some bile salt absorption, production of some SCFAs
What are the broad functions of the rectum / anus?
Defaecation
What divides the gut into its compartment?
Sphincters
How is the gut controlled?
Autonomic nervous system (sympathetic and parasympathetic)
Enteric nervous system
Hormones and paracrine substances
What do the parasympathetic post ganglionic fibres release?
ACh
Peptides - Gatrin releasing peptide, Vaso-inhibitory peptide
Where do the parasympathetic preganglionic fibres synapse?
In the walls of the viscera
At what vertebral levels are the sympathetic nerves of the gut located?
T5-L2
After passing through the sympathetic trunk without synapsing, what do the sympathetic nerves of the gut form?
They form abdominopelvic presynaptic splanchnic nerves
Greater splanchnic nerve (T5-T9)
Lesser splanchnic nerve (T10-T11)
Least splanchnic nerve IT12)
Where do the parasympathetic nerves mainly originate?
Brain and sacral spine (craniosacral)
What are the two main plexuses of the enteric nervous system?
Submucosal (Meissner’s) - in the submucosa
Myenteric (Auerbach’s) - in between circular and longitudinal muscle
