Peripheral Nervous System Flashcards
What are the 2 divisions of the peripheral nervous system?
- Somatic
2. Autonomic - Parasympathetic & Sympathetic
Where do the autonomic preganglionic neurons synapse with the postganglionic neurons?
At the autonomic ganglia
How is the adrenal medulla innervated?
Preganglionic sympathetic neurons - nictoninc - Ach - Epi, NE
What is the predominant NT of the periphery?
Ach
Name the receptor & NT that is released:
Preganglionic parasympathetic
Postganglionic parasympathetic
Preganglionic sympathetic
Postganglionic sympathetic
Preganglionic sympathetic to adrenal medulla
Postganglionic sympathetic to sweat glands - muscarinic, Ach
Motor neuron
Preganglionic parasympathetic - nicotinic, Ach
Postganglionic parasympathetic - muscarinic, Ach
Preganglionic sympathetic - nicotinic, Ach
Postganglionic sympathetic - adrenergic, NE
Preganglionic sympathetic to adrenal medulla - nicotinic, Ach
Postganglionic sympathetic to sweat glands - muscarinic, Ach
Somatic motor neuron - nicotinic, Ach
Name 3 places nicotinic receptors are found.
- Autonomic ganglia
- Cells of the adrenal medulla
- Motor end-plate of skeletal muscle
Name the 2 types of cholinergic receptors.
- Muscarinic
2. Nicotinic
List the fiber types from LARGEST diameter to SMALLEST diameter (FASTEST to SLOWEST).
A-alpha A-beta A-gamma A-delta B sC dC
Which fibers are myelinated? Unmyelinated?
Myelinated: A-alpha, A-beta, A-gamma, A-delta, B
Unmyelinated: sC, dC
A-alpha Fibers
Motor & Sensory
Muscle length & force
Proprioception
Somatic motor neurons
A-beta Fibers
Motor & Sensory
Touch & pressure
Proprioception
A-gamma Fibers
Motor only
Skeletal muscle tone
A-delta Fibers
Sensory only
Pain, temp, & touch
B Fibers
Preganglionic autonomic neurons
sC Fibers
Postganglionic sympathetic neurons
dC Fibers
Sensory only
Pain, temp, & touch
The sympathetic, or __________, nervous system outflow arises from what segments?
Thoracolumbar
T1 to L2or3
Where dos most preganglionic sympathetic neurons synapse with postganglionic neurons?
Paravertebral ganglia
The stellate ganglion is formed by what to ganglia?
Inferior cervical ganglia
First thoracic ganglia
*In 80% of people, these 2 ganglia are fused
If you block — Horner’s syndrome - miosis, ptosis, anhydrosis on the IPSILATERAL side
Interscalene or supraclavicular blocks
Sympathetic preganglionic neurons arise in the ___________ and pass out of the spinal cord via the ___________ root.
Intermediolateral horn of the spinal cord Anterior root (SNS stimulation = efferent/motor)
Describe the fate of sympathetic preganglionic neurons arising in the intermediolateral horn of the spinal cord.
Start: Intermediolateral horn of the spinal cord
Exit: anterior root
ALL PREganglionic neurons pass through the WHITE rami on their way to the paravertebral ganglia
3 fates:
1. Synapse in the paravertebral ganglia…then the POSTganglionic neurons pass through the GRAY rami to reach the spinal nerve
2. Ascend or descend prior to synapse
3. Synapse in the peripheral ganglia
Preganglionic white rami are distributed to spinal nerves arising from ____. Postganglionic gray rami are distributed to ___ spinal nerves from the ganglia.
T1-L2
ALL
*Gray rami allow coordinated, mass discharge of the SNS.
What happens when presynaptic alpha-2 receptors are stimulated by NE or any other drug with alpha-2 receptor agonist activity?
The synthesis and release of NE is DECREASED
Negative feedback
Describe the formation of NE and Epi.
Tyrosine from bloodstream to nerve terminal - Dopa - Dopamine - presynaptic vesicle - NE - adrenal medulla - Epi
*Adrenal medulla pool - 80% Epi, 20% NE
Detail the termination of NE.
1st step is diffusion away from the receptors
80% reuptake into the presynaptic nerve terminal
MAO found in the synaptic cleft
COMT found in the bloodstream
Where are alpha-2 receptors found? What are their actions at these 3 sites?
- Sympathetic postganglionic, presynaptic nerve varicosities - inhibition of NE synthesis and release
- Sympathetic postganglionic, postsynaptic receptors in the brainstem - inhibition of SNS outflow
- Sympathetic postganglionic, postsynaptic receptors in the substantia gelatinosa - analgesia
Beta-2 receptor stimulation is inhibitory in what 2 places?
- Lungs
- Uterus
* Stimulation of beta-2 receptors in smooth muscle is INHIBITORY
What 2 side effects of beta-2 receptor stimulation should you consider?
- Glycogenolysis and gluconeogenesis - BG will increase
2. Na-K pump stimulation - K is driven into cell, HYPOkalemia results