Slides 1 to 145 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Nervous System Two Organ Systems Control All the Other Organ Systems Nervous system characteristics Rapid response Brief duration Endocrine system characteristics Slower response Long duration Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Nervous System Two Anatomical Divisions Central nervous system (CNS) Brain Spinal cord Peripheral nervous system (PNS) All the neural tissue outside CNS Afferent division (sensory input) Efferent division (motor output) Somatic nervous system Autonomic nervous system Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

“INPUT” Figure 8-1 2 of 7 PERIPHERAL NERVOUS SYSTEM Receptors Somatic sensory receptors (monitor the outside world and our position in it) Visceral sensory receptors (monitor internal conditions and the status of other organ systems) “INPUT” Figure 8-1 2 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

“INPUT” Figure 8-1 3 of 7 PERIPHERAL NERVOUS SYSTEM Receptors Sensory information within afferent division Receptors Somatic sensory receptors (monitor the outside world and our position in it) Visceral sensory receptors (monitor internal conditions and the status of other organ systems) “INPUT” Figure 8-1 3 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

“INPUT” Figure 8-1 4 of 7 CENTRAL NERVOUS SYSTEM PERIPHERAL NERVOUS Information Processing PERIPHERAL NERVOUS SYSTEM Sensory information within afferent division Receptors Somatic sensory receptors (monitor the outside world and our position in it) Visceral sensory receptors (monitor internal conditions and the status of other organ systems) “INPUT” Figure 8-1 4 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

“INPUT” “OUTPUT” Figure 8-1 5 of 7 CENTRAL NERVOUS SYSTEM PERIPHERAL Information Processing PERIPHERAL NERVOUS SYSTEM Sensory information within afferent division Motor commands within efferent division Receptors Somatic sensory receptors (monitor the outside world and our position in it) Visceral sensory receptors (monitor internal conditions and the status of other organ systems) “INPUT” “OUTPUT” Figure 8-1 5 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

“INPUT” “OUTPUT” Figure 8-1 6 of 7 CENTRAL NERVOUS SYSTEM PERIPHERAL Information Processing PERIPHERAL NERVOUS SYSTEM Sensory information within afferent division Motor commands within efferent division includes Somatic nervous system Receptors Effectors Somatic sensory receptors (monitor the outside world and our position in it) Visceral sensory receptors (monitor internal conditions and the status of other organ systems) Skeletal muscle “INPUT” “OUTPUT” Figure 8-1 6 of 7 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

CENTRAL NERVOUS SYSTEM Information Processing This diagram is on next test. You need to fill in the boxes and know the function of each branch. PERIPHERAL NERVOUS SYSTEM Sensory information within afferent division Motor commands within efferent division includes Somatic nervous system Autonomic nervous system Parasympathetic division Sympathetic division Receptors Effectors Smooth muscle Figure 8-1 7 of 7 Somatic sensory receptors (monitor the outside world and our position in it) Visceral sensory receptors (monitor internal conditions and the status of other organ systems) Skeletal muscle Cardiac muscle Glands Adipose tissue “INPUT” “OUTPUT”

Nervous System Overview Red = CNS Blue = PNS

The Autonomic Nervous System Branch of nervous system that coordinates cardiovascular, digestive, excretory, and reproductive functions Should the lower text be 30 pt? Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Autonomic Nervous System

Neural Tissue Organization Two Classes of Neural Cells Neurons For information transfer, processing, and storage Neuroglia Supporting framework for neurons Phagocytes = eat up microbes Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Organization Neuroglia in the CNS Figure 8-4

Neural Tissue Organization Three Classes of Neurons Sensory neurons Deliver information to CNS Motor neurons Stimulate or inhibit peripheral tissues Interneurons (=association neurons) Located between sensory and motor neurons Analyze inputs, coordinate outputs Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Organization Neuron Anatomy Cell body Nucleus Mitochondria, RER, other organelles Dendrites Several branches Signal reception and transmission toward cell body Axon Signal propagation Away from cell body Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Organization Anatomy of a Motor Neuron This diagram is on next test. You need to label the parts. Figure 8-2

Neural Tissue Organization Two Types of Neuroglia in the PNS Satellite cells Surround cell bodies Schwann cells Surround all peripheral axons Form myelin sheath on myelinated axons Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Organization Schwann Cells and Axons of Peripheral Neurons Figure 8-5

Neural Tissue Organization Key Note Neurons perform all of the communication, information processing, and control functions of the nervous system. Neuroglia outnumber neurons and have functions essential to preserving the physical and biochemical structure of neural tissue and the survival of neurons. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neuron Function The Membrane Potential Resting Membrane Potential (RMP) Excess negative charge inside the neuron. Excess positive charge outside. Maintained by Na+/K+ ion pump (uses ATP) Negative voltage (potential) inside -70 mV (0.07 Volts) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neuron Function The Cell Membrane at the Resting Potential This diagram is on next test. You need to label each item in this diagram. There will be a checklist of parts to assist you. Figure 8-7

Neuron Function Changes in Membrane Potential Result from changes in ion movement Ions move thru trans-membrane channels Some membrane channels can open or close. Some membrane channels are always open (=“leak channels.”) If Na+ channels open  positive charges enter cell  membrane potential becomes more (+). (This is called depolarization.) If K+ channels open  positive charges leave cell  membrane potential becomes more (-). (This is called hyperpolarization.) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neuron Function Key Note A membrane potential exists across the cell membrane because (1) the cytosol and the extracellular fluid differ in their ionic composition, and (2) the cell membrane is selectively permeable to these ions. The membrane potential can quickly change, as the ionic permeability of the cell membrane changes, in response to chemical, pressure, light, sound, etc stimuli. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neuron Function Generation of Action Potential Gradual depolarization of membrane until it reaches the threshold Rapid opening of voltage-gated Na+ channels Na+ entry causes rapid depolarization (spike in graph) Then voltage-gated K+ channels open K+ ions exit causing rapid repolarization Refractory period ends as membrane restores the RMP, thanks to the Na+/K+ pumps. An action potential is all-or-none!

Transmembrane potential (mV) Depolarization to threshold Sodium ions Local current +30 DEPOLARIZATION Transmembrane potential (mV) _ Threshold 60 _ 1 70 Resting potential 1 2 3 Time (msec) Figure 8-8 2 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Transmembrane potential (mV) Activation of voltage- regulated sodium channels and rapid depolarization Depolarization to threshold Sodium ions Local current Potassium ions +30 DEPOLARIZATION 2 Transmembrane potential (mV) _ Threshold 60 _ 1 70 Resting potential 1 2 3 Time (msec) Figure 8-8 3 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Transmembrane potential (mV) Activation of voltage- regulated sodium channels and rapid depolarization Depolarization to threshold Sodium ions Local current Potassium ions Inactivation of sodium channels and activation of voltage-regulated potassium channels +30 DEPOLARIZATION REPOLARIZATION 3 2 Transmembrane potential (mV) _ Threshold 60 _ 1 70 Resting potential 1 2 3 Time (msec) Figure 8-8 4 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Transmembrane potential (mV) Activation of voltage- regulated sodium channels and rapid depolarization Depolarization to threshold Sodium ions Local current Potassium ions Inactivation of sodium channels and activation of voltage-regulated potassium channels This graph is on the second test. You need to know what is occurring during each phase of the graph and why it is occurring. +30 DEPOLARIZATION REPOLARIZATION 3 2 Transmembrane potential (mV) The return to normal permeability and resting state _ Threshold 60 _ 1 70 4 Resting potential REFRACTORY PERIOD Figure 8-8 5 of 5 1 2 3 Time (msec) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neuron Function Propagation of an Action Potential “Continuous” propagation Involves entire membrane surface Proceeds in series of small steps (so it’s slower) Occurs in unmyelinated axons “Saltatory” (= leaping/hopping) propagation Involves patches of membrane exposed at nodes (spaces between myelin sheath) Proceeds in series of large steps (so it’s faster) Occurs in myelinated axons

Neuron Function The Propagation of Action Potentials over Unmyelinated Axons Figure 8-9(a)

Neuron Function The Propagation of Action Potentials over Myelinated Axons Figure 8-9(b)

Neuron Function Key Note “Information” travels within the nervous system primarily in the form of propagated electrical signals known as action potentials. The most important information (e.g., vision, balance, movement), is carried by myelinated axons. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Communication Synapse Basics Intercellular communication Axon terminal Input to next cell Chemical signaling Neurotransmitter release Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Communication Structure of a Synapse Presynaptic components Axon terminal Synaptic knob Synaptic vesicles Synaptic cleft Postsynaptic components Neurotransmitter receptors Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Structure of a Typical Synapse Neural Communication The Structure of a Typical Synapse Figure 8-10

Neural Communication Synaptic Function and Neurotransmitters Cholinergic synapses Release neurotransmitter acetylcholine Enzyme in synaptic cleft (acetylcholinesterase) breaks it down Adrenergic synapses Release neurotransmitter norepinephrine Dopaminergic synapses Release neurotransmitter dopamine Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Figure 8-11 2 of 5 An action potential arrives and depolarizes the synaptic knob PRESYNAPTIC NEURON Action potential Synaptic vesicles EXTRACELLULAR FLUID ER Synaptic knob AChE POSTSYNAPTIC NEURON CYTOSOL Figure 8-11 2 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Figure 8-11 3 of 5 An action potential arrives and depolarizes the synaptic knob Extracellular Ca2+ enters the synaptic cleft triggering the exocytosis of ACh PRESYNAPTIC NEURON Action potential Synaptic vesicles EXTRACELLULAR FLUID ACh ER Synaptic knob Synaptic cleft Ca2+ Ca2+ AChE Chemically regulated sodium channels POSTSYNAPTIC NEURON CYTOSOL Figure 8-11 3 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Figure 8-11 4 of 5 An action potential arrives and depolarizes the synaptic knob Extracellular Ca2+ enters the synaptic cleft triggering the exocytosis of ACh PRESYNAPTIC NEURON Action potential Synaptic vesicles EXTRACELLULAR FLUID ACh ER Synaptic knob Synaptic cleft Ca2+ Ca2+ AChE Chemically regulated sodium channels POSTSYNAPTIC NEURON CYTOSOL ACh binds to receptors and depolarizes the postsynaptic membrane Initiation of action potential if threshold is reached Na2+ Receptor Na2+ Na2+ Na2+ Na2+ Figure 8-11 4 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Figure 8-11 5 of 5 An action potential arrives and depolarizes the synaptic knob Extracellular Ca2+ enters the synaptic cleft triggering the exocytosis of ACh PRESYNAPTIC NEURON Action potential Synaptic vesicles EXTRACELLULAR FLUID ACh ER Synaptic knob Synaptic cleft Ca2+ Ca2+ AChE Chemically regulated sodium channels POSTSYNAPTIC NEURON CYTOSOL ACh is removed by AChE (acetylcholinesterase) ACh binds to receptors and depolarizes the postsynaptic membrane Initiation of action potential if threshold is reached Propagation of action potential (if generated) Na2+ Receptor Na2+ Na2+ Na2+ Na2+ Figure 8-11 5 of 5 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Communication Key Note A synaptic terminal releases a neuro-transmitter that binds to the postsynaptic cell membrane. The result is a brief, local change in the permeability of the postsynaptic cell. Many drugs affect the nervous system by stimulating neurotransmitter receptors and thus produce complex effects on perception, motor control, and emotions. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Organization Anatomic Organization of CNS Neurons Nucleus—A center with a discrete anatomical boundary Gray matter covering of brain portions. Made up of neuron cell bodies White matter—Bundles of axons (tracts) that share origins, destinations, and functions Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Organization Anatomic Organization of PNS Neurons Ganglia—Groupings of neuron cell bodies Nerve—Bundle of axons supported by connective tissue Spinal nerves To/from spinal cord Cranial nerves To/from brain Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Neural Tissue Organization The Anatomical Organization of the Nervous System Figure 8-6

The Central Nervous System Meninges—Layers that surround and protect the brain and spinal cord (CNS) Dura mater (“tough mother”) Tough, fibrous outer 2 layers. Dural sinus between them contains CSF. Epidural space above dura of spinal cord Arachnoid (“spidery”) Subarchnoid space Cerebrospinal fluid Pia mater (“delicate mother”) Thin inner layer Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System The Cranial Meninges Figure 8-13(a)

The Central Nervous System The Spinal Meninges Figure 8-13(b)

The Central Nervous System Spinal Cord Basics Relays information to/from brain Processes some information on its own Divided into 31 segments Each segment has a pair of: Dorsal root ganglia Dorsal roots Ventral roots Gray matter appears as horns White matter organized into columns Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System Gross Anatomy of the Spinal Cord Figure 8-14(a)

The Central Nervous System Gross Anatomy of the Spinal Cord Red rectangles indicate structures to memorize. Figure 8-14(b)

The Central Nervous System Functional Anatomy of the Spinal Cord Figure 8-15(a)

The Central Nervous System Sectional Anatomy of the Spinal Cord Figure 8-15(b)

The Central Nervous System Key Note The sensory and motor nuclei (gray matter) of the spinal cord surround the central canal. Sensory nuclei are dorsal, motor nuclei are ventral. A thick layer of white matter consisting of ascending and descending axons covers the gray matter. These axons are organized into columns of axon bundles with specific functions. This highly organized structure can enable a clinician to predict the impact of a particular injury. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System Brain Regions Cerebrum Midbrain Pons Medulla oblongata Cerebellum Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System Superior View of Brain Figure 8-16(a)

The Central Nervous System Lateral View of Brain Figure 8-16(b)

The Central Nervous System Mid-sagittal Section of Brain Figure 8-16(c)

The Central Nervous System Brain Ventricles —The four hollow chambers in the center of the brain filled with cerebrospinal fluid (CSF) CSF circulates From ventricles and central canal To subarachoid space Accessible by lumbar puncture To blood stream Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System The Ventricles of the Brain Figure 8-17

The Central Nervous System Functions of the Cerebrum Conscious thought Intellectual activity Memory Origin of complex patterns of movement Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System Anatomy of Cerebral Cortex Highly folded surface (increases S.A.) Elevated ridges (gyri) = “hills” Shallow depressions (sulci) = “valleys” Cerebral Hemispheres Longitudinal fissure Central sulcus (very impt landmark) Boundary between frontal and parietal lobes Lateral sulcus – separates temporal lobe. Other lobes (temporal, occipital) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System Functions of the Cerebral Cortex Hemispheres serve opposite body sides Primary motor cortex (pre-central gyrus) Directs voluntary movement Primary sensory cortex (post-central gyrus) Receives somatic sensation (touch, pain, pressure, temperature) Association areas Interpret sensation Coordinate movement Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System The Surface of the Cerebral Hemispheres Figure 8-19

The Central Nervous System Hemispheric Lateralization Left hemisphere General interpretative and speech centers Language-based skills Right hemisphere Spatial relationships Logical analysis Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System Hemispheric Lateralization Figure 8-20

The Central Nervous System Brain Waves (Electroencephalogram) Figure 8-21

The Central Nervous System Anatomy and Function of the Cerebellum Oversees postural muscles (these are the muscles that maintain posture and correct body position in different situations.) Stores patterns of movement Fine tunes most movements/balance Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System Functions of the Medulla Oblongata Controls crucial organ systems by reflex Cardiovascular centers (regulation of heart rate) Respiratory rhythmicity centers (regulation of breathing rate) very important for overall homeostasis Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Central Nervous System Key Note The brain, a large mass of neural tissue, contains internal passageways and chambers filled with CSF. The six major regions of the brain have specific functions. As you ascend from the medulla oblongata to the cerebrum, those functions become more complex and variable. Conscious thought and intelligence are provided by the cerebral cortex. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Peripheral Nervous System PNS Basics Links the CNS with the body Carries all sensory information and motor commands Axons bundled in nerves Cell bodies grouped into ganglia Includes cranial nerves (12 pairs) and spinal nerves (31 pairs) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Peripheral Nervous System The Cranial Nerves Someday you may have to learn these names. Figure 8-25(a)

The Peripheral Nervous System Key Note The 12 pairs of cranial nerves are responsible for the special senses of smell, sight, and hearing/balance, and control movement of the eye, jaw, face, tongue, and muscles of the neck, back, and shoulders. They also provide sensation from the face, neck, and upper chest and autonomic innervation to thoracic and abdominopelvic organs. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Peripheral Nervous System Dermatomes very important! each shaded region corresponds to a specific spinal nerve diagram enables diagnosing problems in a specific nerve or nerve root A dermotome = a region of the body surface monitored by a pair of spinal nerves Left side of picture = anterior view Right side of picture = posterior view Figure 8-27

The Peripheral Nervous System Reflex—An automatic involuntary motor response to a specific stimulus The 5 steps in a reflex arc Arrival of stimulus and activation of receptor Activation of sensory neuron CNS processing of information Activation of motor neuron Response by effector (muscle or gland) See the next 5 slides for examples of these. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Arrival of stimulus and activation of receptor Stimulus Figure 8-27 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Dorsal root Arrival of stimulus and activation of receptor Activation of a sensory neuron Receptor Stimulus KEY Sensory neuron (stimulated) Figure 8-27 3 of 6 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Sensation relayed to the brain by collateral Dorsal root Arrival of stimulus and activation of receptor Activation of a sensory neuron Receptor Stimulus Information processing in CNS KEY Sensory neuron (stimulated) Excitatory interneuron Figure 8-27 4 of 6 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Sensation relayed to the brain by collateral Dorsal root Arrival of stimulus and activation of receptor Activation of a sensory neuron REFLEX ARC Receptor Stimulus Ventral root Information processing in CNS Activation of a motor neuron KEY Sensory neuron (stimulated) Excitatory interneuron Motor neuron (stimulated) Figure 8-27 5 of 6 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Sensation relayed to the brain by collateral Dorsal root Arrival of stimulus and activation of receptor Activation of a sensory neuron REFLEX ARC Receptor Stimulus Effector Ventral root Information processing in CNS Response by effector Activation of a motor neuron KEY Sensory neuron (stimulated) Excitatory interneuron Motor neuron (stimulated) Figure 8-27 6 of 6 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Peripheral Nervous System Examples of Reflexes touching hot stove (a “withdrawal” reflex) “stretch reflex” - regulates muscle length and tension (example: patellar reflex aka “knee jerk reflex”) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Stretching of muscle tendon stimulates muscle spindles Muscle spindle (stretch receptor) Stretch Spinal cord Figure 8-29 2 of 3 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Stretching of muscle tendon stimulates muscle spindles Muscle spindle (stretch receptor) Stretch Spinal cord REFLEX ARC Contraction Activation of motor neuron produces reflex muscle contraction Figure 8-29 3 of 3 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Peripheral Nervous System The Flexor Reflex, a Type of Withdrawal Reflex Figure 8-30

The Peripheral Nervous System Key Note Reflexes are rapid, automatic responses to stimuli that “buy time” for the planning and execution of more complex responses that are often consciously directed. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Autonomic Nervous System Divisions of the ANS Sympathetic division Preganglionic neurons in the thoracic and lumbar segments of the spinal cord “Fight or flight” system Parasympathetic division Preganglionic neurons in the brain and sacral segments “Rest and digest” system Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Autonomic Nervous System Key Note The two divisions of the ANS operate largely without our awareness. The sympathetic division increases alertness, metabolic rate, and muscular abilities; the parasympathetic division reduces metabolic rate and promotes visceral activities such as digestion. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Autonomic Nervous System The Somatic and Autonomic Nervous Systems The Organization of the Somatic and Autonomic Nervous System Figure 8-33(b)

The Autonomic Nervous System The Sympathetic Division Figure 8-34

The Autonomic Nervous System Effects of Sympathetic Activation Generalized response in crises Increased alertness Feeling of euphoria and energy Increased cardiovascular activity Increased respiratory activity Increased muscle tone Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Autonomic Nervous System The Parasympathetic Division Figure 8-35

The Autonomic Nervous System Effects of Parasympathetic Activation Relaxation Food processing Energy absorption Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Autonomic Nervous System Relationship between the Two Divisions Sympathetic division reaches visceral and somatic structures throughout the body Parasympathetic division reaches only visceral structures via cranial nerves or in the abdominopelvic cavity Many organs receive dual innervation In general, the two divisions produce opposite effects on the their target organs Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings