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7
The Nervous System
PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University
ESSENTIALS
OF HUMAN
ANATOMY
& PHYSIOLOGY
EIGHTH EDITION
ELAINE N. MARIEB
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Functional Classification of Neurons
 Sensory (afferent) neurons
 Carry impulses from the sensory receptors
 Cutaneous sense organs
 Motor (efferent) neurons
 Carry impulses from the central nervous
system
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Functional Classification of Neurons
 Interneurons (association neurons)
 Found in neural pathways in the central
nervous system
 Connect sensory and motor neurons
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Neuron Classification
Figure 7.6
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
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
Figure 7.11a
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Simple Reflex Arc
Figure 7.11b–c
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Types of Reflexes and Regulation
 Autonomic reflexes
 Smooth muscle regulation
 Heart and blood pressure regulation
 Regulation of glands
 Digestive system regulation
 Somatic reflexes
 Activation of skeletal muscles
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Autonomic Reflexes
 Abdominal Reflex
 Stimulus: light stroking of the abdomen
 Response: Contraction of the abdominal
muscles that pull navel towards stimulus
 Spinal Segment: T7 - T12
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Somatic Reflexes
 Biceps Reflex
 Stimulus: tap to tendon of biceps brachii
muscle
 Response: Flexion at elbow
 Spinal Segment: C5, C6
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Somatic Reflexes
 Triceps Reflex
 Stimulus: Tap to tendon of triceps brachii
muscle
 Response: Extension at elbow
 Spinal Segment: C6, C7
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Somatic Reflexes
 Patellar Reflex
 Stimulus: tap to patellar tendon
 Response: extension at knee
 Spinal Segment: L2-L4
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
Somatic Reflexes
 Ankle-jerk Reflex
 Stimulus: Tap to calcaneal tendon
 Response: extension (plantar flexion) at ankle
 Spinal Segment: S1-S2
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings