Actions of the Autonomic Nervous System on Selected Effector Organs.
The somatic nervous system
controls voluntary activity. This system contains long axons that originate in the spinal cord and directly innervate skeletal striated muscle.
Neurotransmitters of the autonomic and somatic nervous systems
- ACh is released by exocytosis from nerve terminals.
- ACh is the neurotransmitter across synapses at the ganglia of the SNS and PNS and across synapses in tissues innervated by the PNS and the somatic nervous system.
- ACh is synthesized in nerve terminals by the cytoplasmic enzyme choline acetyltransferase, which catalyzes the transfer of an acetate group from acetyl coenzyme A to choline that has been transported into “cholinergic” neurons by a sodiumdependent membrane carrier. Synthesized ACh is transported from cytoplasm to vesicle-associated transporters.