Postganglionic neurons

Definition

Postganglionic neurons are the second-order neurons in the autonomic nervous system that transmit signals from the autonomic ganglia to the target organs. They serve as the final relay in the autonomic pathways, responsible for the efferent control of various physiological functions.

5 Must Know Facts For Your Next Test

1. Postganglionic neurons release neurotransmitters, such as acetylcholine or norepinephrine, to stimulate or inhibit the activity of the target organs.
2. The sympathetic and parasympathetic divisions of the autonomic nervous system both utilize postganglionic neurons to convey their respective signals to the effector organs.
3. Postganglionic neurons have a shorter length compared to preganglionic neurons, as they only need to travel from the autonomic ganglia to the target organ.
4. Dysfunction or disruption of postganglionic neurons can lead to various autonomic disorders, such as orthostatic hypotension, urinary incontinence, and impaired sweating.
5. Certain drugs, such as alpha-blockers and beta-blockers, can selectively target and modulate the activity of postganglionic neurons to manage autonomic imbalances.

Review Questions

• Explain the role of postganglionic neurons in the divisions of the autonomic nervous system.
  • Postganglionic neurons are the key components that link the autonomic ganglia to the target organs in both the sympathetic and parasympathetic divisions of the autonomic nervous system. They transmit signals from the autonomic ganglia, where they receive input from the preganglionic neurons, to the effector organs, allowing for the efferent control of various physiological functions. The specific neurotransmitters released by the postganglionic neurons, such as acetylcholine or norepinephrine, determine the overall effect on the target organ, whether it is stimulation or inhibition.
• Describe how the function of postganglionic neurons contributes to autonomic reflexes and homeostasis.
  • Postganglionic neurons play a crucial role in the execution of autonomic reflexes, which are rapid, involuntary responses to changes in the internal or external environment. These neurons transmit the efferent signals from the autonomic ganglia to the target organs, allowing for the immediate adjustment of physiological parameters, such as heart rate, blood pressure, and digestive function, to maintain homeostasis. Disruption or dysfunction of postganglionic neurons can lead to impaired autonomic reflexes and the inability to effectively regulate homeostatic processes, resulting in various autonomic disorders.
• Analyze how drugs that affect the autonomic system can target and modulate the activity of postganglionic neurons.
  • Certain pharmacological agents, such as alpha-blockers and beta-blockers, can selectively target and modulate the activity of postganglionic neurons to manage autonomic imbalances. By interfering with the neurotransmitter release or receptor binding at the postganglionic neuron level, these drugs can alter the efferent signals transmitted to the target organs, resulting in desired physiological effects. For example, alpha-blockers can inhibit the action of norepinephrine on postganglionic neurons, leading to vasodilation and a reduction in blood pressure. Similarly, beta-blockers can block the action of norepinephrine on postganglionic neurons, resulting in decreased heart rate and contractility. Understanding the role of postganglionic neurons in the autonomic system is crucial for the development and application of drugs that can effectively manage autonomic disorders.

Related terms

Preganglionic neurons: Preganglionic neurons are the first-order neurons in the autonomic nervous system that transmit signals from the central nervous system to the autonomic ganglia, where they synapse with the postganglionic neurons.

Autonomic ganglia: Autonomic ganglia are collections of neuronal cell bodies located outside the central nervous system, where the preganglionic neurons synapse with the postganglionic neurons.

Efferent pathways: Efferent pathways are the neural pathways that carry signals from the central nervous system to the target organs, including the postganglionic neurons of the autonomic nervous system.