Final answer:
The sympathetic postganglionics are mostly c) C fibers, which are involved in transmitting various autonomic responses, including those that lead to pupil dilation and increased heart rate. Preganglionic sympathetic fibers originating in the spinal cord can project to the heart and influence cardiac function.
Step-by-step explanation:
The sympathetic postganglionics are mostly c. C fibers. These unmyelinated axons are responsible for transmitting pain, temperature, and postganglionic sympathetic signals. Sympathetic activation is associated with effects such as pupil dilation and increased heart rate.
Preganglionic sympathetic neurons, which may project to the heart, originate in the spinal cord and can influence cardiac function. A drug that affects both divisions of the autonomic system may influence nicotinic or muscarinic receptors, depending on its mechanism of action.
A nerve in the peripheral nervous system is a bundle of axons, and the sympathetic nervous system plays a critical role in the 'fight or flight' response, opposing the actions of the parasympathetic nervous system. Among the cranial nerves, the facial nerve (CN VII) contains preganglionic parasympathetic fibers. These fibers are part of the system that regulates body functions during rest and digest states.