Innervation of the viscera refers to the process by which the nerves of the autonomic nervous system supply and control the functioning of the internal organs (viscera) in the body. The autonomic nervous system is a division of the peripheral nervous system that regulates involuntary bodily functions, including heart rate, digestion, respiration, and glandular secretion.
The innervation of the viscera involves two main branches of the autonomic nervous system: the sympathetic and parasympathetic divisions. The sympathetics are responsible for the "fight-or-flight" response, while the parasympathetics promote the "rest-and-digest" response.
Sympathetic innervation of the viscera arises from the thoracic and lumbar regions of the spinal cord, through a chain of ganglia, and terminates on smooth muscles, blood vessels, and glands within the organs. It generally promotes increased activity and energy expenditure, such as accelerating heart rate, dilating bronchial tubes, and decreasing digestion.
Parasympathetic innervation, on the other hand, originates from the brainstem and sacral region of the spinal cord. It has the opposite effect on the viscera, promoting relaxation and conservation of energy. It slows down heart rate, contracts bronchial tubes, and stimulates digestion and nutrient absorption.
The balance between sympathetic and parasympathetic innervation of the viscera is crucial for maintaining homeostasis and ensuring proper organ functioning. Dysfunction in the innervation can lead to various disorders, including gastrointestinal motility disorders, cardiovascular abnormalities, and respiratory problems.
