1. Functional Classification of Neurons
Sensory (afferent) neurons
Carry impulses from the sensory receptors
Motor (efferent) neurons
Carry impulses from the central nervous system
Slide 7.14a
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2. Functional Classification of Neurons
Interneurons
Found within the central nervous system
Connect sensory and motor neurons
Slide 7.14b
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3. The Reflex Arc
Reflex – rapid, predictable, and involuntary responses to stimuli
Reflex arc – direct route from a sensory neuron, to an interneuron, to an effector
Only to spinal cord, not brain
Figure 7.11a
Slide 7.23
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4. Simple Reflex Arc Figure 7.11b, c Slide 7.24
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5. Types of Reflexes and Regulation
Autonomic reflexes
Smooth muscle regulation
Somatic reflexes
Activation of skeletal muscles
Slide 7.25
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6. Spinal Cord Anatomy Exterior white matter – conduction tracts
Figure 7.19
Slide 7.53a
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7. Spinal Cord Anatomy Internal gray matter - mostly cell bodies
Dorsal (posterior) horns
Anterior (ventral) horns
Figure 7.19
Slide 7.53b
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8. Spinal Cord Anatomy Central canal filled with cerebrospinal fluid
Figure 7.19
Slide 7.53c
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9. Spinal Cord Anatomy Meninges cover the spinal cord
Nerves leave at the level of each vertebrae
Slide 7.54
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10. Peripheral Nervous System
Nerve = bundle of neuron fibers
Neuron fibers are bundled by connective tissue
Slide 7.55
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11. Structure of a Nerve Endoneurium surrounds each fiber
Groups of fibers are bound into fascicles by perineurium
Fascicles are bound together by epineurium
Figure 7.20
Slide 7.56
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12. Classification of Nerves
Mixed nerves – both sensory and motor fibers
Afferent (sensory) nerves – carry impulses toward the CNS
Efferent (motor) nerves – carry impulses away from the CNS
Slide 7.57
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13. Cranial Nerves
12 pairs of nerves emerge from the brainstem and mostly serve the head and neck
Numbered in order, front to back
Most are mixed nerves, but three are sensory only
Slide 7.58
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14. Distribution of Cranial Nerves
Figure 7.21
Slide 7.59
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15. Cranial Nerves I Olfactory nerve – sensory for smell
II Optic nerve – sensory for vision
III Oculomotor nerve – motor fibers to eye muscles
IV Trochlear – motor fiber to eye muscles
Slide 7.60
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16. Cranial Nerves
V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles
VI Abducens nerve – motor fibers to eye muscles
VII Facial nerve – sensory for taste; motor fibers to the face
VIII Vestibulocochlear nerve – sensory for balance and hearing
Slide 7.61
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17. Cranial Nerves
IX Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx
X Vagus nerves – sensory and motor fibers for pharynx, larynx, and viscera
XI Accessory nerve – motor fibers to neck and upper back
XII Hypoglossal nerve – motor fibers to tongue
Slide 7.62
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18. Spinal Nerves
There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs
Spinal nerves are formed by the combination of the ventral and dorsal roots of the spinal cord
Slide 7.63
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19. Anatomy of Spinal Nerves
Spinal nerves divide soon after leaving the spinal cord
Dorsal rami – serve the skin and muscles of the posterior trunk
Ventral rami – forms a complex of networks (plexus) for the anterior
Figure 7.22b
Slide 7.65
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20. Autonomic Nervous System
The involuntary branch of the nervous system
Consists of only motor nerves
Divided into two divisions
Sympathetic division
Parasympathetic division
Slide 7.67
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21. Differences Between Somatic and Autonomic Nervous Systems
Effector organs
Somatic – skeletal muscle
Autonomic – smooth muscle, cardiac muscle,and glands
Slide 7.68a
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22. Differences Between Somatic and Autonomic Nervous Systems
Neurotransmitters
Somatic – always use acetylcholine
Autonomic – use acetylcholine, epinephrine, or norepinephrine
Slide 7.68b
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23. Comparison of Somatic and Autonomic Nervous Systems
Figure 7.24
Slide 7.69
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24. Anatomy of the Sympathetic Division
Originates from T1 through L2
Ganglia are at the sympathetic trunk (near the spinal cord)
Short pre-ganglionic neuron and long postganglionic neuron transmit impulse from CNS to the effector
Norepinephrine and epinephrine are neurotransmitters to the effector organs
Slide 7.70
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25. Sympathetic Pathways Figure 7.26 Slide 7.71
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26. Anatomy of the Parasympathetic Division
Originates from the brain stem and higher portion of spinal cord
Always uses acetylcholine as a neurotransmitter
Slide 7.72
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27. Anatomy of the Autonomic Nervous System
Figure 7.25
Slide 7.73
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28. Autonomic Functioning
Sympathetic – “fight-or-flight”
Response to unusual stimulus
Takes over to increase activities
Remember as the “E” division = exercise, excitement, emergency, and embarrassment
Slide 7.74a
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29. Autonomic Functioning
Parasympathetic – housekeeping activites
Conserves energy
Maintains daily necessary body functions
Remember as the “D” division - digestion, defecation, and diuresis
Slide 7.74b
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