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Chapter 11 Autonomic Nervous System

Chapter 11 Autonomic Nervous System. p.261. Comparison of Somatic and Autonomic Nervous Systems. Effectors Cardiac muscle Smooth muscle Glands (somatic – skeletal muscles) Control Involuntary Regulated mainly by hypothalamus & brain stem (somatic – voluntary).

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Chapter 11 Autonomic Nervous System

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  1. Chapter 11Autonomic Nervous System p.261

  2. Comparison of Somatic and Autonomic Nervous Systems • Effectors • Cardiac muscle • Smooth muscle • Glands (somatic – skeletal muscles) • Control • Involuntary • Regulated mainly by hypothalamus & brain stem (somatic – voluntary)

  3. Comparison of Somatic and Autonomic Nervous Systems(cont.) • Neural pathway • Sensory neurons monitor internal conditions • Usually not consciously perceived • Motor neurons regulate visceral activities • Generally can’t be consciously altered to a great degree • 2 sets of neurons • Preganglionic – from CNS to ganglion (myelinated) • Postganglionic – from ganglion to effector (unmyelinated) • Autonomic ganglion (somatic – 1 motor neuron extends from CNS to effector)

  4. Comparison of Somatic and Autonomic Nervous Systems(cont.) • Neurotransmitter • 2 types • Dual innervation • Excitatory vs. inhibatory • Sympathetic division vs. parasympathetic division (somatic – 1 type; always excitatory)

  5. Structure of the Autonomic Nervous System • Preganglionic Neurons • Sympathetic preganglionic neurons • Thoracolumbar division • Parasympathetic preganglionic neurons • Craniosacral division • Nearly 80% of outflow carried by vagus nerve

  6. Structure of the Autonomic Nervous System (cont.) • Autonomic Ganglia • Sympathetic ganglia • Sympathetic trunk ganglia • Near spinal cord; in 2 vertical rows • Supply organs above diaphragm • Prevertebral ganglia • Anterior to vertebral column; close to large abdominal arteries • Supply organs below diaphragm • (Adrenal medulla) • Release hormones into blood • Intensify sympathetic responses • Parasympathetic ganglia • Terminal ganglia • Close to or within walls of innervated organs • Supply structures in head, thorax, & abdomen

  7. Structure of the Autonomic Nervous System (cont.) • Postganglionic Neurons • Sympathetic postganglionic neurons • 4 possible pathways (p.266) • Branches of 1 preganglionic neuron may synapse with 20 or more different postganglionic neurons • Affect organs throughout the body simultaneously • Parasympathetic postganglionic neurons • Very short • Preganglionic neurons synapse with only 4 or 5 similar postganglionic neurons • Responses are localized to a single effector

  8. Functions of the Autonomic Nervous System • ANS Neurotransmitters • Cholinergic neurons • Includes: • All preganglionic neurons, • All parasympathetic postganglionic neurons • Some sympathetic postganglionic neruons • Release acetylcholine • Effects are short-lived and localized • Enables precise control • Adrenergic neurons • Includes: • Most sympathetic postganglionic neurons • Release norepinephrine • Effects are longer lasting and more widespread

  9. Functions of the Autonomic Nervous System (cont.) • Activities of the ANS • “Tone” is regulated by hypothalamus • Typically sympathetic & parasympathetic are regulated oppositely together. • Some structures receive only sympathetic innervation

  10. Functions of the Autonomic Nervous System(cont.) • Activities of the ANS (cont.) • Sympathetic activities • Stimulated by: • Physical exertion • Fear • Embarrassment • Rage • Produces “fight-or-flight” response • Supports vigorous activity & rapid ATP production • Reduces body functions that store energy • Inhibits nonessential processes

  11. Functions of the Autonomic Nervous System (cont.) • Activities of the ANS (cont.) • Sympathetic activities (cont.) • “E situations” • Exercise • Emergency • Excitement • Embarrassment

  12. Functions of the Autonomic Nervous System (cont.) • Activities of the ANS (cont.) • Parasympathetic activities • Stimulated by: • Quiet periods • Paradoxical fear • Produces “rest-and-digest” response • Supports body functions that conserve and restore body energy • Reduce body functions that support physical activity SLUDD

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