Information Transmission
Messages travel through the SNS in a bidirectional flow. Efferent messages can trigger changes in different parts of the body simultaneously. For example, the sympathetic nervous system can accelerate heart rate; widen bronchial passages; decrease motility (movement) of the large intestine; constrict blood vessels; increase peristalsis in the esophagus; cause pupillary dilation, piloerection (goose bumps) and perspiration (sweating); and raise blood pressure. Afferent messages carry sensations such as heat, cold, or pain.
The first synapse (preganglionic neuron to postganglionic neuron in the sympathetic chain) is mediated by nicotinic receptors physiologically activated by acetylcholine. The target synapse of the postganglionic neuron is mediated by adrenergic receptors and is physiologically activated by either noradrenaline (norepinephrine) or adrenaline (epinephrine). An exception is with sweat glands, which receive sympathetic innervation but have muscarinic acetylcholine receptors, which are normally characteristic of Parasympathetic nervous system. Another exception is with certain deep muscle blood vessels, which dilate (rather than constrict) with an increase in sympathetic tone. This is because of the presence of more beta2 receptors (rather than alpha1, which are frequently found on other vessels).
Read more about this topic: Sympathetic Nervous System
Famous quotes containing the word information:
“Computers are good at swift, accurate computation and at storing great masses of information. The brain, on the other hand, is not as efficient a number cruncher and its memory is often highly fallible; a basic inexactness is built into its design. The brain’s strong point is its flexibility. It is unsurpassed at making shrewd guesses and at grasping the total meaning of information presented to it.”
—Jeremy Campbell (b. 1931)