Diarrhea and Constipation Flashcards
Intrinsic innervation of small intestine and colon comprises of
myenteric, submucosal and mucosal neuronal layers
Functions of myenteric, submucosal and mucosal neuronal layers are regulated by
interneurons, through actions of amines or peptides including acetylcholine, vasoactive intestinal peptides , opioids, NE, Serotonin, ATP, NO
Smooth muscle function is regulated by
Myenteric plexus
Secretion, Absorption and Blood flow is affected by
Submucosal plexus
Extrinsic innervation of small intestine and colon are part of autonomic nervous system and modulates the
motor and sensory functions
Parasympathetic nerves convey
visceral sensory and excitatory pathways to the colon
Parasympathetic fibers reach the small intestine and proximal colon via
vagus nerve, along the branches of the superior mesenteric artery
Distal colon is supplied by
sacral parasympathetic nerves (S2-S4) via the pelvic plexus
Chief excitatory neurotransmitters controlling motor functions are
Acetylcholine, and tachykinin such as Substance P
Sympathetic nerve supply modulates
motor function and reaches the small intestine and colon alongside the arterial vessels
Sympathetic input to the gut is usually
Excitatory to sphincters, Inhibitory to non sphincteric muscles
On an avg day , ____ fluid enter the GIT
9 Litres
On an avg day, ___ residual fluid reach the colon
about 1 Litres
On an avg day, ____ fluid is the stool excretion
0.2 L/d
In the colon, Sodium absorption is predominantly electrogenic and uptake takes place at
Apical membrane
______ and _____ also influence colonic absorption
Angiotensin and Aldosterone
During fasting, the motility of the small intestine is characterized by a cyclical event called
Migrating motor complex (MMC) — serves to clear nondigestible residue from the intestine
MMC contractions on average lasts ____, occurs every ____ min and usually involve the entire ____
4 min, 60-90 min , small intestine
Distal ileum acts as a reservoir by
emptying intermittently by bolus movement
Segmentation by haustra compartmentalizes the colon and facilitates
mixing, retention of residue and formation of solid stools
In normal healthy person, the ascending and transverse regions of colon functions as reservoirs with transit time of
average transit 15h
descending colon acts as a conduit with transit time of
average transit 3 h
Colon is efficient at conserving
sodium and water
Diarrhea or constipation results from
Alteration in the reservoir function of the proximal colon or the propulsive function of the left colon
Constipation might occur as a result of
rectal or sigmoid reservoir disturbances, typically as result of dysfunction of pelvic floor, anal sphincters or coordination of defecation
Small intestinal MMC rarely continues into the
Colon
