Oesophagus Anatomy and Physiology Flashcards
what are the 4 main layers of the digestive tract wall? (from inner to outer)
mucosa, submucosa, muscularis externa, serosa
where are the circular muscles and lengthen located as part of the tract wall?
muscularis externa
where is the muscularis mucosae located as part of the tract wall?
mucosa
what is a function of the muscularis mucosae?
folds to aid in absorptive and secretory functions
what type of muscles are in the upper 1/3 of the oesophagus?
striated skeletal muscle
what type of muscles are in the lower 2/3 of the oesophagus?
smooth muscle
what is the general mechanism of peristalsis?
wave of RELAXATION followed by CONTRACTION which is triggered by gut wall distension
do slow wave potentials always cause peristalsis?
NO there must be another stimulus (which causes depolarisation by opening Ca2+ channels to achieve threshold)
in peristalsis what is contraction mediated by?
ACh
in peristalsis what is relaxation mediated by?
NO and VIP
what happens infront of a bolus?
circular muscle relaxes and longitudinal muscle contracts
what happens behind a bolus?
circular muscle contracts and longitudinal muscle relaxes
what does contraction of longitudinal muscle do?
makes it shorter and fatter
what does contraction of circular muscle do?
makes it longer and narrower
