Motility ceases since the muscularis mucosa is the most sensitive region to hypoxia. Epithelial sloughing initially involves the crypt cells and progresses towards the villus tip. The counter-current circulation allows the villus tip to remain oxygenated despite hypoxic conditions. Further intestinal degeneration after correction of the lesion is related to lipid peroxidation. By definition, true peristaltic contractions are elicited only by the presence of a food bolus.
Secondary peristalsis refers to the anti-peristaltic movement noted during regurgitation.
Primary peristalsis is essential for secondary peristalsis to occur. Secondary peristalsis is elicited by the presence of a foreign body or food bolus. Duration of action of ultrashort-acting barbiturates is primarily dependent upon redistribution to lean body tissues. Glycerol guaiacolate produces relaxation of skeletal muscles, laryngeal and pharyngeal muscles, and the diaphragm. Ketamine hydrochloride produces apneustic breathing and tachycardia.