GI System - Neural Innervation Flashcards
The neurons of the ENS are arranged into two plexi. Name them.
Myenteric
Submucosal
Which plexus mostly controls GI tract motility?
Myenteric (Auerbach), as it is located between the inner circular and outer longitudinal layers of the muscularis.
What is the function of the motor neurons of the Submucosal plexus?
Supplies the secretory cells of the mucosal epithelium.
Controls secretions of the GI tract.
What is the function of interneurons of the ENS?
Connects the myenteric and Submucosal plexuses.
Sensory neurons of the ENS have two sensory functions. What are they?
Chemoreceptors - activated by certain chemicals digested in the lumen of a GI organ.
Stretch receptors - activated when food distends or stretches the wall of a GI organ.
What regulates ENS activity?
Autonomic Nervous System
Where the vagal parasympathetic fibres innervate?
Most of the GI tract.
Exception: last half of the large intestine
What part of ANS supplies the last half of the large intestine?
Parasympathetic fibres of the sacral spinal cord
Where do sympathetic nerves which supply the GI tract arise from in the spinal cord?
Thoracic and upper lumbar regions of the spinal cord
Name the foregut structures
Oesophagus Stomach Liver Gall bladder Pancreas Spleen Proximal half of duodenum
Name the midgut structures
Distal half of duodenum Ileum Jejunum Caecum Appendix Ascending Colon Proximal 2/3rds of the Transverse Colon
Name the Hindgut Structures
Distal Third of the Transverse Colon
Descending Colon
Sigmoid Colon
Rectum
Upper Anal Canal
What is branches off the aorta to provide the foregut structures with a blood supply?
Celiac Trunk
What branches off the aorta to provide the midgut structures with a blood supply?
Superior Mesenteric Artery
What branches off the aorta to provide the hindgut structures with a blood supply?
Inferior Mesenteric Artery
