Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The Autonomic Nervous System and Visceral Sensory Neurons The Autonomic Nervous System Innervates smooth muscle, cardiac muscle, and glands Regulates visceral functions Heart rate, blood pressure, digestion, urination The general visceral motor division of the PNS
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The Autonomic Nervous System and Visceral Sensory Neurons Figure 15.1
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Comparison of Autonomic and Somatic Motor Systems Somatic motor system One motor neuron extends from the CNS to skeletal muscle Axons are well myelinated, conduct impulses rapidly
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Comparison of Autonomic and Somatic Motor Systems Autonomic nervous system Chain of two motor neurons Preganglionic neuron Postganglionic neuron Conduction is slower due to thinly or unmyelinated axons Pre-ganglionic Ganglion Post-ganglionic
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Anatomical Differences in Sympathetic and Parasympathetic Divisions Length of postganglionic fibers Sympathetic – long postganglionic fibers Parasympathetic – short postganglionic fibers Branching of axons Sympathetic axons – highly branched Influences many organs Parasympathetic axons – few branches Localized effect
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Autonomic and Somatic Motor Systems Figure 15.2
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Divisions of the Autonomic Nervous System Sympathetic and parasympathetic divisions Innervate mostly the same structures Cause opposite effects
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Divisions of the Autonomic Nervous System Sympathetic – “fight, flight, or fright” Activated during exercise, excitement, and emergencies Parasympathetic – “rest and digest” Concerned with conserving energy
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Figure 15.3 Anatomical Differences in Sympathetic and Parasympathetic Divisions Issue from different regions of the CNS Sympathetic – also called the thoracolumbar division Parasympathetic – also called the craniosacral division
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Sympathetic Division of the ANS Figure 15.7
Radial
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The Role of the Adrenal Medulla in the Sympathetic Division Major organ of the sympathetic nervous system Secretes great quantities epinephrine (a little norepinephrine) Stimulated to secrete by preganglionic sympathetic fibers
Stress ↑ sympathetic system ↑ fight-or-flight response. ↑ production of ATP. Dilation of the pupils. ↑ heart rate and blood pressure. Dilation of the airways. Constriction of blood vessels that supply the kidneys and gastrointestinal tract. ↑ blood supply to the skeletal muscles, cardiac muscle, liver and adipose tissue ↑ glycogenolysis ↑ blood glucose. ↑ lipolysis. E “ Situation ” Exercise, Emergency, Excitement and Embarrassment.
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The Parasympathetic Division Figure 15.5
Circular
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings The Parasympathetic Division Cranial outflow Comes from the brain Innervates organs of the head, neck, thorax, and abdomen Sacral outflow Supplies remaining abdominal and pelvic organs
Rest-and-digest response. Conserve and restore body energy. ↑ digestive and urinary function. ↓ body functions that support physical activity. SLUDD (SalivationLacrimationUrinationDigestionDefecation ) “ Three decreases ” (heart, diameter of airways and pupils)
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Neurotransmitters of Autonomic Nervous System Neurotransmitter released by preganglionic axons Acetylcholine for both branches (cholinergic) Neurotransmitter released by postganglionic axons Sympathetic – most release norepinephrine (adrenergic) Parasympathetic – release acetylcholine
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Anatomical Differences in Sympathetic and Parasympathetic Divisions Figure 15.4a
Copyright © 2005 Pearson Education, Inc., publishing as Benjamin Cummings Anatomical Differences in Sympathetic and Parasympathetic Divisions Figure 15.4b