lecture 24 - GI motility and physiology Flashcards
what do receptors in the wall of the GI tract respond to
stretch, change in composition, ph, osmolarity, amino acids, sugars and fats
what do reflexes (stimulated by receptors) in the GI tract stimulate
- smooth muscle contraction
- gland secretion
what does the parasympathetic nervous system do in the GI tract
stimulates motility and secretion
what does the sympathetic nervous system do in the GI tract
inhibits motility and secretion
what does the submucosal plexus do in the enteric nervous system
regulation of secretion
what does the myenteric plexus do in the enteric nervous system
regulation of motility
is the enteric nervous system self contained
yes
what is endocrine hormonal regulation in the GI tract
signalling using circulatory system to transport signals
what is paracrine hormonal regulation in the GI tract
signalling acts on near by cells
what are tonic contractions
sustained contractions for minutes to hours (e.g sphincters)
what are phasic contractions
waves of contraction and relaxation, each wave lasting seconds (e.g peristalsis)
what is a motility pattern
any contraction or relaxation of GI tract smooth muscle
- some motility patterns can be a combination of two or more simpler patterns (e.g retropulsion)
what is GI tract motility like in terms of contraction
contracts without external input
- spontaneously active
what happens in the GI tract when you are fasting
housekeeping = removes residual secretions, removes undigested material, promotes epithelial cell turnover
what happens in the GI tract when you are in a feeding state
storage, propulsion and mixing
