The Nervous System Sensory Systems

PRINCIPLES OFHUMAN PHYSIOLOGY

THIRD EDITION

Cindy L. Stanfield | William J. Germann

PowerPoint® Lecture Slides prepared by W.H. Preston, College of the Sequoias

Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings.

10

Part D

The Nervous System:

Sensory Systems


Anatomy of the Ear

Figure 10.37


Generation of Sound Waves

Figure 10.38a


Properties of Sound

Figure 10.38b


Anatomy of Middle Ear

Figure 10.39


Sound Transduction: Cochlea

Figure 10.40a, c


Sound Transduction: Cochlea

Figure 10.40e–f


Functional Anatomy of Cochlea

Figure 10.40e–f


Inner Hair Cells: Sound Conduction

Figure 10.41


Hair Cells: Sound Transduction

Figure 10.42a–c


Sound Frequency Coding

Figure 10.43


Clinical Defects: Deafness

• Conductive deafness

• Inadequate conduction of sound waves through external and/or middle ear

• Sensorineural deafness

• Inadequate transduction of sound waves to electrical signals in inner ear

• Central deafness

• Damage to the neural pathway for sound


V. The Ear and Equilibrium

• Anatomy of the vestibular apparatus

• The semicircular canals and the transduction of rotation

• The utricle and saccule and the transduction of linear acceleration

• Neural pathways for equilibrium


Anatomy of Vestibular Apparatus

Figure 10.44


Semicircular Canal Anatomy

Figure 10.45a–b


Coding for Acceleration

Figure 10.45c–e


Anatomy: Utricle and Saccule

Figure 10.46a


Coding for Acceleration

Figure 10.46b–d


Coding for Head Tilting

Figure 10.46e–f


Neural Pathways for Equilibrium

Vestibular afferents

Vestibular nuclei(brainstem)

Cerebellum Cortex

Balance &Equilibrium

Perception

Sensory systems

Eye movements


Taste Buds

• Over 10,000 taste buds

• Tongue

• Roof of mouth

• Pharynx

• Pore exposed to saliva in mouth

• 50–150 taste receptors cells per bud

• Modified epithelial cells

• Respond to tastants

• Support cells


Taste Receptors

Figure 10.47


Transduction of Sour and Salty

Figure 10.48a–b


Transduction of Sweet and Bitter

Figure 10.48c–d


Neural Coding of Taste

Figure 10.49


Olfactory Epithelium

Figure 10.50


Olfactory Receptor Cells

• Only neurons replaced continuously

• Cilia project into mucus

• Have chemoreceptors

• Olfactory binding proteins

• Located in mucus

• Transport odorants to receptors


Olfactory Signal Transduction

• Air-borne chemical must dissolve in mucus

• Olfactory binding proteins deliver olfactants to receptors


Olfactory Signal Transduction

• Chemical binds to receptor

• Activates G protein called Golf

• Activates adenylate cyclase cAMP

• cAMP directly binds cation channels, opening them

• Na+ and Ca2+ enter cell depolarization

• Specificity of binding

• Specific olfactory receptor cells for each type of odorant-binding protein


Neural Pathway for Olfaction

• Olfactory receptor cells are specialized endings of afferent neurons

• Axon of receptor cells comprises CN I, the olfactory nerve

• Second order neurons = mitral cells



• Communication between afferent and second-order neuron occurs in glomeruli

• Second-order neurons form olfactory tract

• Relay in olfactory tubercle to cerebral cortex



Figure 10.51

The Nervous System Sensory Systems

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