Ch. 29: Introduction to the Autonomic Nervous System Vocabulary

acetylcholinesterase

enzyme responsible for the immediate breakdown of acetylcholine when released from the nerve ending; prevents overstimulation of cholinergic receptor sites

adrenergic receptors

receptor sites on effectors that respond to norepinephrine/epinephrine

alpha-receptors

adrenergic receptors that are found in smooth muscles of blood vessels, the eyes, and a variety of other organs

autonomic nervous system

portion of the central and peripheral nervous systems that, with the endocrine system, functions to maintain internal homeostasis

beta-receptors

adrenergic receptors that are found in the heart, lungs, bladder, uterus, and vascular smooth muscle cholinergic receptors: receptor sites on effectors that respond to acetylcholine

ganglia

groups of closely packed nerve cell bodies

monoamine oxidase

enzyme that breaks down norepinephrine, dopamine, and serotonin to make them inactive

muscarinic receptors

cholinergic receptors that are stimulated by postganglionic nerves; located in visceral effector organs such as the GI tract, bladder, and heart; in sweat glands; and in some vascular smooth muscle

nicotinic receptors

cholinergic receptors that respond to stimulation by nicotine; located between pre- and postganglionic nerves and also at the neuromuscular junctions

parasympathetic nervous system

contains central nervous system (CNS) cells from the cranium or sacral area of the spinal cord, long preganglionic axons, ganglia near or within the effector tissue, and short postganglionic axons that react with cholinergic receptors; responsible for most unconscious actions; sometimes called the “rest-and-digest” or “feed-and-breed” system

sympathetic nervous system

composed of CNS cells from the thoracic or lumbar areas, short preganglionic axons, ganglia near the spinal cord, and long postganglionic axons that react primarily with adrenergic receptors; functions as the antagonist of the parasympathetic system; and prepares the body to respond to stress; sometimes called the “fight-or-flight” system