Seeley/Anatomy and Physiology

Lecture Outline

CHAPTER OVERVIEW: This chapter introduces the autonomic nervous system. The structures and functions of each of the divisions of the ANS are reviewed. Comparisons and contrasts are drawn between the somatomotor and autonomic portions of the peripheral nervous system, especially in terms of the pharmacology of the synapses, the number and organization of neurons, and the effector organs innervated.

OUTLINE (two fifty-min. lectures):

Chapt. Object.	Topic Outline, Chapter 16	Figures & Tables	Trnspcy. Acetates	Trnspcy. Masters
1	I. Contrasting Somatic Motor and Autonomic Nervous Systems	Table 16.1, p.505
	A. Somatic Motor System
	1. Single Cells Extending From CNS
	2. Innervate Skeletal Muscles
	3. All Conscious and Unconscious Movements of Skeletal Muscles
	B. Autonomic Nervous System
2	1. Series of Two Neurons from CNS to Effector	Fig. 16.1, p.505	TA-206
	a. Preganglionic Neuron - Cell Body in CNS
	b. Postganglionic Neuron - Cell Body in Autonomic Ganglion
	2. Innervate Smooth Muscle, Cardiac Muscle and Glands
	3. Unconscious or Subconscious Control of Visceral Organs

	II. Divisions of the Autonomic Nervous System	Table 16.2, p.506
3	A. Sympathetic Division	Fig. 16.2, p.506	TA-207
	1. Preganglionic Cell Bodies in CNS - Thoracolumbar Division
	a. Gray Matter of Lateral Horns of Spinal Cord
	b. Level of T1 to L2 - Thoracolumbar Division
	2. Preganglionic Axons (Myelinated)
	a. Ventral Spinal Root to White Rami Communicantes	Fig. 16.3, p.507
	b. Through White Rami to Sympathetic Chain Ganglia
4	c. Exit is by One of Four Routes
	1). Synapse with Postganglionic Fiber in Chain Ganglion	Fig. 16.3a,b, p.507	TA-208
	a). Unmyelinated Postganglionic Fiber Through Gray Ramus Back to Spinal Nerve
	b). Postganglionic Fiber Forms Sympathetic Nerve
	2). Pass Through Chain Ganglion Without Synapsing	Fig. 16.3c,d, p.507	TA-209
	a). Form Splanchnic Nerves; Synapse at Collateral (Prevertebral) Ganglia
	b). Preganglionic Neurons End at Synapse with Secretory Cells of Adrenal Medulla; 80% Release Epinephrine, 20% Release Norepi-nephrine
3	B. Parasympathetic Division	Fig. 16.4, p. 508	TA-210
	1. Preganglionic Cell Bodies in CNS - Craniosacral Division
	a. Brainstem Nuclei for Cranial Nerves
	b. Lateral Horns of Spinal Gray Matter, Level S2 to S4
	2. Preganglionic Axons Travel
	a. From Brain to Terminal Ganglia via Cranial Nerves
	1). Oculomotor (III)
	2). Facial (VII)
	3). Glossopharyngeal (IX)
	4). Vagus (X) - 75% of All Parasympathetic Axons
	b. From Sacral Region to Terminal Ganglia via Ventral Roots of Pelvic Nerves
	3. Terminal Ganglia Located at or Near Organ Innervated	Clinical Note, p.509

	III. Physiology of the Autonomic Nervous System
5	A. Neurotransmitters	Fig. 16.5, p.510	TA-211
	1. Acetylcholine
	a. Released by Cholinergic Neurons
	b. All Preganglionic Neurons of ANS
	c. All Parasympathetic Postganglionic Neurons
	d. Some Sympathetic Postganglionic Neurons to Sweat Glands
	2. Norepinephrine
	a. Released by Adrenergic Neurons
	b. Most Sympathetic Postganglionic Neurons
6, 10	B. Receptors	Clinical Focus, p.512
7	1. Cholinergic Receptors	Predict Quest. 1
	a. Nicotinic Receptors
	1). Cell Bodies of All Postganglionic Neurons (Both Parasymp. and Symp.)
	2). Membranes of Skeletal Muscle Cells
	3). Effect Always Excitatory
	b. Muscarinic Receptors
	1). All Parasympathetic Effector Cells
	2). At Sympathetic Effector Cells Receiving Cholinergic Innervation
	3).Effect Excitatory at Some Cells, Inhibitory at Others
	2. Adrenergic Receptors	Fig. 16.5, p.510; Table 16.3, p.511; Clinical Note, p.528
	a. Types
	1). Alpha (a) - Binds Epinephrine and Norepinephrine
	2). Beta (b) - Binds Epinephrine but Less Well to Norepinephrine
	b. Distribution on Sympathetic Effector Cells
	1). Some Alpha Only
	2). Some Beta Only
	3). Some Have Both Types
	c. Effect Excitatory at Some Cells and Inhibitory at Others

	IV. Regulation of the Autonomic Nervous System
8	A. Autonomic Reflexes Regulate Activity of Visceral Organs, Glands, and Blood Vessels	Fig. 16.6, p.513; Predict Quests. 2 & 3	TA-212
	B. Same Parts as Somatic Reflexes
	C. Influenced by Activity in Hypothalamus and Higher Brain Centers	Fig. 16.7, p. 514		TM-58

9, 10	V. Functional Generalizations About the Autonomic Nervous System	Clinical Focus, p.515
	A. Stimulatory vs. Inhibitory Effects
	B. Dual Innervation	Table 16.3, p.511; Fig. 16.8, p.516	TA-213
	C. Opposite Effects D. Cooperative Effects
	1. Coordinated Activity Within a Division
	2. Coordinated Activity Between Divisions (i.e., Reproductive Function)
	E. General Versus Localized Effects
	1. Sympathetic Division Has More Generalized Effect
	a. Systemic Release of Epinephrine from Adrenal Gland
	b. More Divergence of Nerual Connections - One Preganglionic Sympathetic Neuron Synapses with Many Postganglionic Neurons
	2. Parasympathetic Division Has More Localized Effect
	a. Neurotransmitter only Released at Synapses
	b. Little Divergence - One Preganglionic Parasympathetic Neuron Synapses with One or Two Postganglionic Neurons
	F. Functions at Rest Versus Activity	Predict Quest.4
	1. Parasympathetic Effects Greatest Under Resting Conditions
	2. Sympathetic Effects Greatest Under Conditions of Physical Exertion or Stress	Clinical Focus, p.517

IMPORTANT CONSIDERATIONS: The logical break falls so that the structure of the system is in one session and the pharmacology of receptors and regulation of the ANS falls in the second session. Many students will find their first introduction to the neurotransmitters, receptors and target cells of the autonomic nervous system to be confusing. The concept of dual innervation is also difficult for many students to grasp initially.

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