Efferent Peripheral Nervous Divisions cont. Autonomic Motor - innervates cardiac muscle, smooth muscle, endocrine tissue and adipocytes Somatic Motor - innervates skeletal striated muscle Neurotransmitters and receptors

Human Physiology, 6th ed., Fox, SI; WC Brown, Fig.9.9 ACh neurotransmitter for all preganglionic fibers of both ACh is neurotransmitter for postganglionic of parasympathetic NE is neurotransmitter for postganglionic of sympathetic Human Physiology, 6th ed., Fox, SI; WC Brown, Fig.9.9

Somatic Motor Acetylcholine (ACh) acts on muscle nicotinic ACh receptors Excitatory, causes muscle contraction

Somatic Motor Nervous System Cell bodies in CNS Send single axons to skeletal muscles Excitatory, causes muscle contraction Acetylcholine (ACh) acts on nicotinic ACh receptors

Muscles are innervated by nerves that originate in the brainstem or spinal cord and end at the neuromuscular junction with typically one junction per muscle fiber. ACh (acetylcholine) is the neurotransmitter at all neuromuscular junctions. Not shown is how ACh is rapidly removed following release; otherwise, the action potentials would not cease causing continual contraction. Many drugs, including nerve gases, work at these locations by either blocking the neurotransmitter receptors or inhibiting the removal of the neurotransmitter.

Motor efferent pathways