g.i tract - prof peters Flashcards
carries food and liquid from the mouth to the stomach propelled by ……….?
peristalis
the upper and lower part of the oesophagus are bounded by what?
upper and lower oesophageal sphincters
the oesophagus is lined by what cell type
stratified squamous epithelium
the oesophagus musculature contains, striated and smooth.
what regions of the oesophagus would you find these
striated - upper thrid
smooth - remainder
what nerve innervates the oesophagus
vagus nerve CNX
what triggers the closure of the upper oesophageal sphincter
once food has entered the oesophagus
primary peristaltic wave (vagus nerve)
swallowing centre (pons and medulla)
what is the enteric nervous system
its the nervous sytsem that governs the GI system
what do the circular fibres do behind bolus during peristalsis
contract to squeeze it down to stomach
what do longitudinal fibres infront of bolus do, during peristalsis
contract to shorten distance to travel
after swallowing how many seconds later does the lower oesophageal sphincter open
2-3 seconds
prevents reflux
when would a secondary peristaltic wave occur
when sticky food becomes lodged in the oesophagus
what digest protein in the stomach
pepsin and HCl
approximatley how much gastric juices is produced by the gastric glands
2 litre/day
mechanical activity occurs as two types. what are they
orad stomach
caudad stomach
for storage of ingested material in the stomach. must stomach relax or contract
relax via vagus nerve
would you expect to find greater wave activity in the orad or the caudad region
caudad region
where would you find thick musculature in the stomach
orad region or caudad region
caudad region
why is there minimal mixing of contents for long periods in the orad region
allows for carbohydrate partial digestion by salivary glands
what occurs during retropulsion
mixing of gastric contents, whilst reducing chyme to small particles, so that it passes through the pylorus
Strength of antral wave determines escape of chyme through pyloric sphincter
which is goverened by what
gastric factors
duodenal factors
what are the gastric factors that affect emptying of chyme
stretch of smooth muscle
stimulation of intrinsic nerve plexuses
increased vagus nerve activity and gastrin release
consistency of chyme
what stimuli in the duodenum affects gastric emptying
fat - duodenum needs to prepare
acid - pancrease needs to prepare
hypertoncity - osmotically active
distension
what is the gastric mucosa composed of
lining of stomach
pits, invaginations of the surface
glands, at the base of the pits
in which region of the stomach would you find an increase in parietal and chief cells.
oxyntic or plyoric
oxyntic area
