Peripheral Nervous System: Autonomics Review Flashcards
What is an afferent neuron?
A sensory neuron with information that arrives at the brain.
What is an efferent neuron?
A motor neuron with information that exits the brain.
Anything that is part of the body wall is innervated by which type of nervous system?
Somatic nervous system.
Describe the 2 part relay system of the visceral motor neuron.
The preganglionic cell body in the CNS has an autonomic motor impulse. This impulse moves from the CNS, synapses on the autonomic ganglion and then synapses on the motor tissue, via varying pathways.
Where are the pre- and post-ganglionic cell bodies of the sympathetic nervous system located?
Preganglionic: In the CNS at thoracolumbar: T1-L2/L3
Postganglionic: Synapse at every level of the spinal cord
What are the motor targets of the sympathetic nervous system?
The internal organs and body wall. The body wall consists of hair follicles, sweat glands, etc.
Where are the pre- and post-ganglionic cell bodies of the parasympathetic nervous system located?
Preganglionic: In the CNS at craniosacral: CNs III, VII, IX, X; spinal cord S2-S4
Postganglionic: At or very close to target organ or gland
What are the target organs of the parasympathetic nervous system?
Internal organs only, including the salivary glands. [nothing in the body wall]
What happens if you sever the spinal cord at a level above T1-T4?
The person would develop bradycardia. The cardiopulmonary splanchnic nerve is controlled by the sympathetic system at T1-T4. So, if you sever above this level, the only system working is the parasympathetics, which decrease heart rate.
In order to stop a sympathetic response in the body wall, does the parasympathetic nervous system take over?
No, there is no parasympathetic target in the body wall. So in order to stop a sympathetic response, the sympathetic system must slow down its activity.
What are the nerves of the parasympathetic system?
There are the cranial nerves: CN III, CN VII, CN IX, CN X, and the pelvic splanchnic nerves.
What is cranial nerve X and what does the nerve innervate?
This is the vagus nerve. It innervates all of the GI tract and upper airway. Specifically, it goes to ganglia in the heart, larynx, trachea, stomach, pancreas, etc. The preganglionic neurons in are also in the torso until 2/3 across the transverse colon where the pelvic splanchnic nerves take over.
Which nerves innervate the pelvic viscera, like the reproductive organs and erectile muscles?
The pelvic splanchnic nerves.
How many neurons are involved in the pathway of the GSE system? Describe the pathway.
There is one neuron involved. It leaves the CNS at the ventral horn through the ventral root –> ventral ramus or dorsal ramus –> many places in the body
Describe the 2 part relay system of the GVE: describe the first part and the second part in terms of the general options.
The first part is that motor neurons leave the CNS at the lateral horn –> ventral horn –> ventral root –> ventral ramus –> sympathetic chain (sympathetic ganglion via white communicans). In the second part, the neurons can either synapse immediately, ascend or descend via paravertebral ganglia, or use prevertebral ganglia.
