Organisation of the Peripheral Nervous System Flashcards
Somatic nerves innervate what?
Skeletal muscle
What does the autonomic nervous system regulate?
Cardiac muscle, smooth muscle and glands
What cells secrete epinephrine and norepinephrine?
Chromaffin cells
What neurotransmitter do somatic neurons release?
Acetylcholine
Explain the anatomy of a preganglionic neuron.
The axon of a preganglionic neuron has a small diameter and consists of myelinated type B fibers.
Explain the anatomy of postganglionic neurons.
The axon of a postganglionic neuron has a small diameter and consists of unmyelinated type C fibers.
What do preganglionic neurons do?
Relay nerve impulses from the CNS to autonomic ganglia.
What do postganglionic neurons do?
Relay impulses from autonomic ganglia to visceral effectors.
Which ganglia are associated with the parasympathetic division of the nervous system?
Terminal ganglia
Which ganglia are associated with the sympathetic division of the nervous system?
Prevertebral ganglia
Why do sympathetic ganglions have widespread effects over the entire body?
A sympathetic preganglionic fiber has many axon branches that synapse with 20 or more postganglionic neurons.
The postganglionic axons terminate in several visceral effectors thus leading to widespread effects over the whole body.
Where do the cell bodies of the preganglionic sympathetic neurons located?
Lateral gray horns of the thoracic segments of the spine.
Through what pathway do preganglionic sympathetic neurons run?
White ramus
Through what pathway do postganglionic sympathetic neurons run?
Gray ramus
Where are the cell bodies of parasympathetic preganglionic neurons found?
Nuclei of the brainstem
Lateral gray matter of the second and fourth sacral segments of the spine.
Pelvic splanchnic nerves branch from which spinal nerves?
Second through to fourth sacral spinal nerves