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Unformatted text preview: 9/7/11 1 Autonomic Nervous System Chapter 15 IB 131 Instructor: Tom Carlson Department of Integrative Biology University of California, Berkeley The ANS (Autonomic Nervous System) • The ANS—a system of motor neurons • Innervates • Smooth muscle in organs and blood vessels • Cardiac muscle • Glands The ANS • The ANS—a system of motor neurons – Regulates visceral functions • Heart rate • Blood pressure • Digestion • Urination – The ANS is the • General visceral motor division of the Peripheral Nervous System Figure 15.1 The Autonomic Nervous System and Visceral Sensory Neurons 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 Comparison of Autonomic and Somatic Motor Systems • Autonomic nervous system – Chain of two motor neurons • Preganglionic neuron • Ganglionic neuron (sometimes called post-ganglionic neuron) – Conduction is slower than somatic nervous system due to • Thinly myelinated or unmyelinated axons • Motor neuron synapses in a ganglion 9/7/11 2 Autonomic & Somatic Motor Systems Figure 15.2 Skeletal muscle Cel bodies in central nervous system Peripheral nervous system Effect Effector organs ACh ACh Smooth muscle (e.g., in gut), glands, cardiac muscle Ganglion Adrenal medul a Blood vessel ACh ACh ACh NE Epinephrine and norepinephrine Ganglion Heavily myelinated axon Lightly myelinated preganglionic axon Lightly myelinated preganglionic axons Neurotransmitter at effector Unmyelinated postganglionic axon Unmyelinated postganglionic axon Stimulatory Stimulatory or inhibitory, depending on neuro- transmit er and receptors on ef ector organs Single neuron from CNS to ef ector organs Two-neuron chain from CNS to ef ector organs SOMATIC NERVOUS SYSTEM AUTONOMIC NERVOUS SYSTEM PARASYMPATHETIC SYMPATHETIC Divisions of the Autonomic Nervous System • Sympathetic and parasympathetic divisions – Chains of two motor neurons • Innervate mostly the same structures • Cause opposite effects – Sympathetic division mobilizes the body during extreme “fight or flight” situations – Parasympathetic division controls routine maintenance functions Divisions of the Autonomic Nervous System • Sympathetic —“fight, flight, or fright” – Activated during EXTREME situations • Exercise • Excitement • Emergencies Divisions of the Autonomic Nervous System • Sympathetic responses help us respond to dangerous situations – Increase heart rate and breathing rate – Increases blood and oxygen to skeletal muscles – Dilates pupils and airways – Motility of the digestive tract and urinary tracts are inhibited Divisions of the Autonomic Nervous System • Parasympathetic division – Active when the body is at rest – Concerned with conserving energy – Directs routine activities • Heart rate and breathing are at low- normal levels • Gastrointestinal tract digests food...
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This note was uploaded on 10/14/2011 for the course IB 131 taught by Professor Carlotom during the Spring '11 term at City College of San Francisco.
- Spring '11