ANS Flashcards
Target Organs Innervated by ANS
Cardiac muscle
Smooth muscle
glands
Structural motif
2 neuron relay: one is the preganglionic neuron in the CNS. Then there is a ganglion that exists outside the CNS where the presynapses with a posganglionic neuron.
ACH
Used in poth pre to post neurons. ACH is used at teh PNS site of action.
NE
NE used at the site of action for SNS except for sweat glands and some vasodilatory fibers that ALSO use ACH.
Divergence
The SNS will have axons from one preganglionic cell synapse on numerous ganglia and therefore synapse with many post ganglionic cells, on average 1: 10. The PNS 1:3
SNS spinal level
SNS is thoracolumbar so T1 to L2. The neurons live in the lateral horn as the IML cell column. Their axons then access the peripheral ganglia and commonly the ones that make up the sympathetic trunk of the body , which are at ALL LEVELS of the sp cd and the target tissue is VERY broad.
PNS
craniosacral outflow. It only goes to a few different organs really.
How does the SNS get to the head
Through the vascular system. The superior cervical ganglion at the top of the IML will send out SNS postganglionic fibers to the glands of the face and such to shut down crying and salivation through constricting down the blood supply to these areas. So not stopping function, but cut off energy.
Prevertebral ganglia
The:
Celiac
Superior mesenteric
Inferior mesenteric
SNS to adrenal medulla
Pass through paravertebral ganglion en route to adrenal medualla. EPI released to act systemically in the body. This will mainly be fear response . So AMYGDALA to stria terminalis to hypothalamus paraventricular nuclei to parvocellular cells. CRH released. Cortisol stimulated. Also other paraventricular outflow that will cause SNS activity in the body to increase mainly in the adrenal MEDULLA to cause systemic release of EPI and the wide SNS effects through the body.
Gray rami
Preganglionic axons have many options and these are going through the gray rami. ALL spinal nerves contain gray rami.
White rami
Take preganglionic SNS fiberts to the sympathetic trunk. So the WHITE RAMI are from the paraventricular trunk to the sp cd. They are white because they are MYELINATED . These white ramin only exist from T1 to L2.
T1 to L2
ONLY T1 to L2 contain the WHITE rami that reflex back to the spinal nerve from IML column.
What do the gray rami do
Take the postsynaptic sympathetic fibers back to the spinal nerves and to the output organs and this is why they exist at every level.
4 CN that comprise of the PNS
CN III, VII, IX, X
Edinger-Westphal nucleus
CNIII: PNS axons that runs from the Brainstem Nucleus the Edinger-Westpal nucleus to the peripheral ganglion, the ciliary ganglion and gets to the sphincter pupillae m and cause the pupillary light reflex so constrict the eye