Upper GI Tract Structue and Function Flashcards
describe the reflex control of chewing
contraction of muscles leads to mechanoreceptors being triggered by pressure of food against gums, hard pallet and tongue. this inhibits the jaw muscles causing a reduction in pressure that leads to contraction of jaw muscle.
name five things in oral saliva
> water > mucins >electrolytes > lysozyme > alpha-amylase
what type of saliva is produced by parasympathetic innervation?
> profuse watery secretion
describe saliva secreted by the sympathetic system
> small volume and viscous
high mucous content (alpha-adrenoreceptors)
high amylase content (beta-adrenoreceptors)
name the parasympathetic nerve that stimulated salivation
> cranial
> glossopharyngeal
what type of muscle is found in the top third of the oesophagus?
> skeletal
what part of the oesophagus is smooth muscle?
inferior two thirds
where is the swallowing centre located?
the medulla
describe the pharyngeal reflex
> bolus enters back of mouth
soft palate closes the nasopharynx
upper oesophageal sphincter relaxes
epiglottis covers the opening to the larynx
upper oesophageal sphincter contracts once the bolus has enters the oesophagus
what propels the bolus down the oesophagus?
peristaltic wave
what initiates the receptive relaxation of the stomach?
the relaxation of the lower oesophageal sphincter
what is the effect of the vagus reflex on the stomach volume?
there is an increase in size with no change in pressure
what are the functions of the stomach?
> storage > sterilisation > digestion > delivery of food to small intestine > production of intrinsic factor
