Efferent division

autonomic division

sympathetic, parasympathetic, enteric divisions, target smooth muscle, cardiac muscle, glands, and some adipose tissue

somatic divsion

efferent target is skeletal muscle, output

preganglionic neurons

synapse on postganglionic neurons, use acetylcholine (ACh) binds to nAChRs

post ganglionic neurons

synapse on target tissues

sympathetic preganglionic neurons

originate in thoracic and lumbar spinal regions; shore axons, use norepinephrine, binds to adrenergic receptors (GPCRs)

parasympathetic preganglionic neurons

originate in brainstem, sacral spinal regions; long axons, use ACh bind to mAChRs

sympathetic postganglionic neurons

form 2 chain ganglia, along aorta, long axons

parasympathetic postganglionic neurons

located at tissue level; short axons; vagus nerve is major pathway, form chain ganglia in spinal chord

chromaffin cells

lack axons but secrete 80% epinephrine to 20% norepinephrine

neuroeffector junction

release of NT occurs along varicosities of autonomic axons

adrenergic receptors

GCPRs expressed in target tissues, activated by sympathetic signaling

muscarinic receptors

GPCRs expressed in target tissues, activated by parasympathetic signaling, most tissues express M2 or M3 subtypes

presynaptic cell

motor nerve terrminal

cleft

contains fibrous ECM with the enzyme Acetylcholinesterase

post synpatic cell

motor end plate of the skeletal muscle fiber