Adrenegic drugs

Major portion of the NS (involuntary, unconscious, autonomic portion of the nervous system.

General Organization:

1- Central ANS (hypothalamus).
2- Peripheral ANS, which consists of :

a- Sympathetic (SNS).
b- Parasympathetic (PSNS).
A- Sympathetic Nervous System (SNS)
Spinal Roots of Origin: (Thoraco-lumber)
The sympath. preganglionic fibers originate in the thoracic (T1-T12) & Lumber (L1-L5) segments of the spinal cord.

Location of the ganglia:
Most of the sym. ganglia in 2 para-vertebral chain located along spinal cord.

The pre-ganglionic fibers short
The post -ganglionic fibers long
Summary of sympathetic neurons and synapses
Preganglionic neurons
Short
Synapse with postganglionic neurons near spinal cord
Release acetylcholine (ACH) to activate nicotinic receptors on postganglionic neurons
Postganglionic neurons
Long
Synapse on the target organ
Release norepinephrine to activate adrenergic receptors on target organs
Exceptions in the sympathetic nervous system
Sweat glands:
Postganglionic neurons involved with stress-related excretion release norepinephrine (“sweaty palms”)

Postganglionic neurons involved with thermoregulation release acetylcholine