Preganglionic neuron

Preganglionic neuron refers to a type of neuron that is part of the autonomic nervous system (ANS). These neurons are responsible for transmitting nerve impulses from the central nervous system (CNS) to an autonomic ganglion, where they synapse with postganglionic neurons. Preganglionic neurons play a crucial role in the regulation of involuntary bodily functions, including heart rate, digestion, and respiratory rate.

Structure and Function

Preganglionic neurons are characterized by their location and the neurotransmitter they release. They originate in the spinal cord or the brain and extend to autonomic ganglia, where they release the neurotransmitter acetylcholine. This neurotransmitter binds to nicotinic receptors on the postganglionic neuron, initiating a response in the target organ.

The autonomic nervous system is divided into two main branches: the sympathetic nervous system and the parasympathetic nervous system. Preganglionic neurons of the sympathetic system typically have a short axon and synapse in a ganglion close to the spinal cord. In contrast, preganglionic neurons of the parasympathetic system have a long axon that extends to ganglia located near or within the target organs.

Clinical Significance

Preganglionic neurons are involved in various physiological processes and can be affected by certain medical conditions. For example, damage to these neurons can lead to autonomic dysfunctions, such as Horner's syndrome, which is characterized by ptosis (drooping eyelid), miosis (constricted pupil), and anhidrosis (lack of sweating) on the affected side of the face.

Understanding the function and pathology of preganglionic neurons is essential for diagnosing and treating disorders of the autonomic nervous system. Treatments may involve medications that mimic or block the action of neurotransmitters or surgical interventions to correct abnormalities in the autonomic pathways.

See Also

• Postganglionic neuron
• Autonomic nervous system
• Neurotransmitter
• Acetylcholine
• Sympathetic nervous system
• Parasympathetic nervous system