ABSTRACT
Afferent nerve endings innervating the abdominal visceral region are interoceptors, a group of internal receptors that are located in muscle, abdominal, and thoracic regions. Most organs in the abdominal visceral region have been identified as important sources of afferent neural information. Sensory nerves from the abdominal region are present in spinal, vagus, and sacral nerves. Afferent nerves in the abdominal visceral region terminate either as free or complex endings. Classification of free nerve endings as strictly mechanosensitive or chemosensitive has been debated. Several other pathological conditions may lead to reflex activation of the cardiovascular system by stimulating abdominal afferent nerve endings. Strong cardiorespiratory reflex responses result from stimulation of chemosensitive receptors. The same endogenous and exogenous substances, which stimulate afferent nerve endings, are capable of evoking reflex effects. A functional dichotomy exists between afferent vagal and sympathetic reflexes.
