Download The Nervous System: Sensory Systems

PRINCIPLES OF
HUMAN PHYSIOLOGY
10
THIRD EDITION
Cindy L. Stanfield | William J. Germann
The Nervous
System:
Sensory Systems
Part A
PowerPoint® Lecture Slides prepared by W.H. Preston, College of the Sequoias
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.
Sensory Information
• Somatic sensations
• Special senses
• Somesthetic
• Vision
• Proprioception
• Hearing
• Equilibrium
• Taste
• Smell
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Sensory Receptors
Figure 10.2a
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Sensory Receptors
Figure 10.2b
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Sensory Receptor Characteristics
Table 10.1
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Slow Versus Fast Adaptation
Figure 10.3
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Cortical Sensory Areas
Figure 10.4
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Sensory Units and Receptive Fields
Figure 10.5
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General Sensory Pathway
Figure 10.6
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Stimulus Intensity Coding
Figure 10.7
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Intensity Coding by Recruitment
Figure 10.8a
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Intensity Coding by Recruitment
Figure 10.8b
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Localization Acuity
Figure 10.9
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Secondorder
neurons
X2
Inhibitory
interneurons
Y2
Z2
Inhibitory
interneurons
Frequency of
Action potentials
Lateral Inhibition
Activity in secondorder neurons
Afferent
neurons
(firstorder
neurons)
X1
Y1
Z1
Frequency of
Action potentials
X2
Y2
Z2
Second-order neurons
Activity in
afferent neurons
X1
Y1
Z1
Afferent neurons
Location of stimulus
Figure 10.10
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Two Point Discrimination
Figure 10.11
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Two Point Discrimination
Table 10.2
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Somatosensory Receptors
• Mechanoreceptors
• Thermoreceptors
• Nociceptors
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Types of Skin Receptors
Table 10.3
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Mechanoreceptors of Skin
Figure 10.13
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Characteristics of Thermoreceptors
• Warm receptors
•
Free nerve endings
•
Respond to temperatures from 30–43°C
•
Increase frequency with increase in temperature
• Cold receptors
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•
Possible free nerve endings
•
Respond to temperatures from 35–20°C
•
Increase frequency with decrease in temperature
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Thermoreceptor Responses
Figure 10.14a
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Thermoreceptor Responses
Figure 10.14b
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Characteristics of Nociceptors
• Free nerve endings
• A delta or C fibers
• Classes
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•
Mechanical
•
Thermal
•
Polymodal
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Medial-Lemniscal Pathway
Figure 10.15a
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Spinothalamic Tract
Figure 10.15b
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Anatomy of the Eye
Figure 10.19a
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Retina: Ophthalmoscope
Figure 10.19b
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Electromagnetic Spectrum
Figure 10.21
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Light Refraction by Eye
Figure 10.24
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The Eye: Focusing Far and Near
Figure 10.25a
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The Eye: Focusing Far and Near
Figure 10.25b
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Mechanism of Accommodation
Figure 10.26a
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Mechanism of Accommodation
Figure 10.26b
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Normal Eye (Emmetropia)
Figure 10.27a
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Myopia (Near Sightedness)
Figure 10.27b
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Hyperopia (Far Sightedness)
Figure 10.27c
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Regulation of Light Entering Eye
Figure 10.28b–c
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Anatomy of the Retina
Figure 10.29
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Rod and Cone Distribution
Figure 10.30
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Anatomy of Rods and Cones
Figure 10.31
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Components of Rods
Figure 10.32
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Phototransduction: Dark
Figure 10.33a
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Phototransduction: Light
Figure 10.33b
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Photoreceptor Absorbance Spectra
Figure 10.34
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Photoreceptor Characteristics
Table 10.4
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Going from Light to Dark
• Exposure to light “bleaches” the rods
•
Opsin separated from retinal
•
No more light can be absorbed
• Move to dark
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•
Sensitivity of rods is low due to previous “bleaching”
•
Retinal and opsin reassociate
•
Can again detect light
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Going from Dark to Light
• Exposure to dark maintains rods in most sensitive
state
•
Opsin and retinal associated
•
Readily absorb light
• Move to bright light
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•
Sensitive rods overwhelmed
•
Rods begin to be “bleached”
•
Can again see clearly
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Convergence of Photoreceptors
Convergence of photoreceptors to bipolar cells,
and bipolar cells to ganglion cells
•
•
•
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Convergence
•
More than one photoreceptor to bipolar neuron
•
More than one bipolar cell to ganglion cell
Rods converge more
•
Lower visual acuity
•
Greater sensitivity
In fovea
•
One cone communicates with one bipolar cell
•
Greater acuity
•
Lower sensitivity
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Depth Perception
•
Binocular visual field
•
Two perspectives of
visual field, one from
each eye
•
Brain constructs threedimensional image
Figure 10.36
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