Bio 168 Autonomic Nervous System Study Guide
Fall Semester 2003
Learning Objectives, Topics, Key Words
Reading: Martini, Chapter 16
1. Understand the structural and functional differences between somatic and autonomic
nervous systems.
somatic efferents --> innervate skeletal muscle
somatic = conscious
action is always excitatory
single peripheral synapse
autonomic efferents --> innervate glands, smooth muscle, cardiac muscle (i.e., visceral)
autonomic = unconscious
often, sympathetic opposes parasympathetic (inhibition/excitation)
somatic only excitatory
at least two peripheral synapses
2. Identify the principal structural features of the ANS.
preganglionic neuron (CNS)
myelinated axon
postganglionic neuron (PNS)
unmyelinated axon
parasympathetic: preganglionics are cranio-sacral
sympathetic: preganglionics are thoraco-lumbar
autonomic ganglia (in PNS)
sympathetic ganglia (generally near the CNS)
sympathetic trunk
paravertebral ganglia
prevertebral ganglia (e.g. , splanchnic)
parasympathetic ganglia
terminal ganglia (near or in end organ)
3. Compare the sympathetic and parasympathetic divisions of the ANS (anatomy, physiology, neurotransmitters).
parasympathetic
mainly viscera
"SLUD" [mnemonic for some functions controlled by parasympathetics]
sympathetic
cervical ganglia
viscera and skin
"fight or flight"
4. Describe the various postsynaptic receptors involved in autonomic responses.
parasympathetic (neurotransmitter is acetylcholine (ACh) at all synapses)
nicotinic receptors in ganglia
muscarinic receptors at end organ
sympathetic
nicotinic cholinergic receptors in ganglia
adrenergic receptors on cells of end organ (neurotransmitter is norepinephrine;
exception (at sweat glands): cholinergic
alpha, beta-1, beta-2 adrenergic receptors (receptor determines cellular response)
alpha = vasoconstriction
beta-1 = increase heart rate
beta-2 = relax airway smooth muscle
5. Describe the components of a visceral autonomic reflex.
afferent: visceral receptor (e.g., stretch receptor in the bladder wall)
spinal interneurons
pre- and post-ganglionic neurons
effector: e.g. smooth muscle of bladder)
6. Give examples of the control of the ANS by higher centers.
cerebrum (e.g., fright, biofeedback)
hypothalamus (e.g., temperature, blood pressure)
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Last updated 11 November 2003