postganglionic neuron

Examples of postganglionic neuron in the following topics:

• Postganglionic Neurons

  • At the synapses within the ganglia, the preganglionic neurons release acetylcholine, a neurotransmitter that activates nicotinic acetylcholine receptors on postganglionic neurons.
  • In response to this stimulus, postganglionic neurons—with two important exceptions—release norepinephrine, which activates adrenergic receptors on the peripheral target tissues.
  • The two exceptions mentioned above are the postganglionic neurons of sweat glands and the chromaffin cells of the adrenal medulla.
  • The postganglionic neurons of sweat glands release acetylcholine for the activation of muscarinic receptors.
  • Most transmissions occur in two stages: When stimulated, the preganglionic nerve releases ACh at the ganglion, which acts on the nicotinic receptors of the postganglionic neurons.

• Preganglionic Neurons

  • The ANS is unique in that it requires a sequential two-neuron efferent pathway; the preganglionic neuron must first cross a synapse onto a postganglionic neuron before innervating the target organ.
  • The preganglionic, or first neuron will begin at the outflow and will cross a synapse at the postganglionic, or second neuron's cell body.
  • The postganglionic neuron will then cross a synapse at the target organ.
  • There are several locations where preganglionic neurons create synapses with their postganglionic neurons:
  • These are the preganglionic neurons that synapse with the postganglionic neurons in these locations :

• Autonomic Nervous System

  • The acetylcholine activates the postganglionic neurons.
  • Postganglionic neurons then release norepinephrine onto target organs.
  • The axons of the preganglionic neurons release acetylcholine on the postganglionic neurons, which are generally located very near the target organs.
  • In the autonomic nervous system, a preganglionic neuron of the CNS synapses with a postganglionic neuron of the parasympathetic nervous system.
  • The postganglionic neuron, in turn, acts on a target organ.

• Autonomic Reflexes

  • The ANS is unique in that it requires a sequential two-neuron efferent pathway; the preganglionic neuron must first creat a synapse to a postganglionic neuron before innervating the target organ.
  • The preganglionic, or first neuron will begin at the outflow and will cross a synapse at the postganglionic, or second neuron's cell body.
  • The postganglionic neuron will then create a synapse at the target organ.

• Parasympathetic Responses

  • When stimulated, the preganglionic nerve releases ACh at the ganglion, which acts on nicotinic receptors of the postganglionic neurons.
  • The postganglionic nerve then releases ACh to stimulate the muscarinic receptors of the target organ.

• Autonomic Ganglia

  • Preganglionic nerves from the spinal cord create a synapse end at one of the chain ganglia, and the postganglionic fiber extends to an effector, typically a visceral organ in the thoracic cavity.
  • The first neuron in this pathway is referred to as the preganglionic or presynaptic neuron.
  • This second neuron is referred to as the postganglionic or postsynaptic neuron.
  • The pathways of the ciliary ganglion include sympathetic neurons (red), parasympathetic neurons (green), and sensory neurons (blue).
  • The postganglionic fibers travel from the ganglion to the effector organ.

• Submucosa

  • Tiny parasympathetic ganglia are scattered around forming the submucosal plexus (or "Meissner's plexus") where preganglionic parasympathetic neurons synapse with postganglionic nerve fibers that supply the muscularis mucosae.

• Function and Physiology of the Spinal Nerves

  • Acetylcholine is the preganglionic neurotransmitter for both divisions of the ANS, as well as the postganglionic neurotransmitter of parasympathetic neurons.
  • In the parasympathetic system, ganglionic neurons use acetylcholine as a neurotransmitter to stimulate muscarinic receptors.
  • At the adrenal medulla, there is no postsynaptic neuron.
  • Instead the presynaptic neuron releases acetylcholine to act on nicotinic receptors.
  • Upper motor neurons release acetylcholine.

• Sympathetic Nervous System

  • Preganglionic nerves from the spinal cord create a synapse at one end of the chain ganglia and the postganglionic fiber extends to an effector, typically a visceral organ, in the thoracic cavity.
  • Neurons of the collateral ganglia, also called the prevertebral ganglia, receive input from the splanchnic nerves and innervate organs of the abdominal and pelvic region.

• Classification of Neurons

  • Afferent neurons convey information from tissues and organs into the central nervous system (e.g. sensory neurons).
  • Efferent neurons transmit signals from the central nervous system to the effector cells (e.g. motor neurons).
  • Another way in which neurons are classified is by their effect on target neurons.
  • A neuron releases a neurotransmitter that binds to chemical receptors on the target neuron .
  • Other types of neurons include excitatory motor neurons in the spinal cord that release acetylcholine, and inhibitory spinal neurons that release glycine.