The Gastrointestinal Tract The Esophagus

Distension of the hollow visceral organs is commonly employed to study pain processing from these sites; the esophagus is no exception. Esophageal distension in the anesthetized rat evokes pseudaffective responses including pressor (heart rate and arterial blood pressure) responses concomitant with the stimulus (16). These effects are dependent upon the location of the distension: Significantly greater cardiovascular responses are found in the lower and middle esophagus compared to upper areas (16), suggesting that the lower esophagus should be considered for experiments using such a model. This distension stimulus is administered by the injection of water into a spherical balloon (typically for 20-30 seconds) that is inserted into the distal esophagus under anesthesia following cannulation of the carotid or femoral artery (for measurement of blood pressure and heart rate). Tracheal cannulation ensures a clear airway. These factors mean that such experiments cannot be carried out in free-moving animals; therefore behavioral testing is not possible (but psychophysical studies are often performed in humans who can voluntarily swallow a balloon). As an interesting aside, evidence exists for a significant convergence of esophageal and cardiac afferent pathways (17). For example, patients often perceive (referred) esophageal and cardiac pain in a very similar manner. This phenomenon is not restricted to the esophagus and the heart; thus, one should not necessarily assume that behaviors observed from similar experiments are affecting just one organ or neural pathway.

Baby Sleeping

Baby Sleeping

Everything You Need To Know About Baby Sleeping. Your baby is going to be sleeping a lot. During the first few months, your baby will sleep for most of theday. You may not get any real interaction, or reactions other than sleep and crying.

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