70370 netter129

Motility

GASTROINTESTINAL PHYSIOLOGY

GUT LUMEN

MUCOSA

Ascending (orał) pathway

Excitatory motor neuron (acetylcholine, substance P)

Mechanical

Slimtiblion

Sensory neuron (mechanical, Chemical)

Chemical

stimulation

7 Descending (anal) pathway

Inhibitory motor neuron (VIP, NO)

RHatation

|. Perkins

MS, MFA

⁹ MN

FlCURE 7.7 CONTROl OF PERISULSIS -

The presence ol a bolus of rood in the lumen of the intestine iuses contraction of the smooth muscle above (green arrows) *r<i relaxation below (peach arrows) the bolus. Ihis process -Hilts in a peristaltic wave, which propels the bolus down the

intestine (i.e., trom the mouth toward the anus). This process is coordinated by the enterir. nervous system. The neurons of the myenteric plexus depicted in this figurę resirle in the muscułans externa.

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