preganglionískir

Preganglionic neurons are a crucial component of the autonomic nervous system, which controls involuntary bodily functions such as heart rate, digestion, and respiration. These neurons originate in the central nervous system, specifically within the brainstem or the spinal cord. They are characterized by their long axons, which extend out from the central nervous system to synapse with a second neuron, known as a postganglionic neuron, located in an autonomic ganglion.

The cell bodies of preganglionic neurons are found in specific nuclei within the brainstem for the cranial nerves that are part of the parasympathetic division and in the intermediolateral cell columns of the spinal cord for both the sympathetic and parasympathetic divisions. Their axons are typically myelinated, which allows for rapid transmission of nerve impulses.

In the sympathetic nervous system, preganglionic neurons originate in the thoracic and upper lumbar segments of the spinal cord. In contrast, in the parasympathetic nervous system, they originate in the brainstem (sacral segments of the spinal cord for the pelvic nerves). The neurotransmitter released by preganglionic neurons at the synapse with postganglionic neurons is acetylcholine, which acts on nicotinic acetylcholine receptors on the postganglionic neuron. This transmission is excitatory, triggering the postganglionic neuron to fire its own action potential.