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Chapter 12 Sensory Mechanisms

Types of receptors

Somatic senses

Special senses

Copyright © 2009 Pearson Education, Inc. Table 12.1 (1 of 2)

Types of Receptors

Copyright © 2009 Pearson Education, Inc. Table 12.1 (2 of 2)

Types of Receptors

Copyright © 2009 Pearson Education, Inc. Figure 12.1

Sensory Receptors in Skin

Free nerveendings

Thermo-,light touch,and painreceptors

Modified and encapsulatednerve endings

Merkel disks:light touch

Hair

Free nerveendings:sensechangingpositionof hairs

Meissner’scorpuscle:light touch

Paciniancorpuscle:deep pressureand high-frequencyvibration

Ruffini endings:pressure

Epidermis

Subcutaneouslayer

Dermis

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Special Senses- Taste

Taste buds Chemoreceptors that bind with dissolved

substances

Taste categories Sweet

Salty

Sour

Bitter

Umami

Copyright © 2009 Pearson Education, Inc. Figure 12.5d

Locations and Structure of the Receptors for Taste

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Smell

Olfactory receptor cells Chemoreceptors that bind with odorants

Correlation between taste and smell Chewed food releases chemicals that come

in contact with olfactory receptors

Copyright © 2009 Pearson Education, Inc. Figure 12.6

Olfactory Receptors and the Mucus-Producing Olfactory Glands

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Hearing

Mechanoreceptors detect sound waves

Copyright © 2009 Pearson Education, Inc. Figure 12.9

Structure of the Human Ear

Copyright © 2009 Pearson Education, Inc. Table 12.3

Structures and Functions of the Ear

Copyright © 2009 Pearson Education, Inc. Figure 12.10

Structures and Function of the Cochlea

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Balance: Inner Ear

Specialized structures of inner ear Vestibular apparatus

Three semicircular canals and vestibule

Sensing rotational movement Ampulla with mechanoreceptors in cupula

Sensing head rotation and acceleration Uticle and saccule in vestibule with otoliths

Copyright © 2009 Pearson Education, Inc. Figure 12.13a–c

Sensing Head Position and Acceleration

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Vision

Detecting and interpreting visual stimuli by converting light energy to nerve impulses and transmitting them to the brain

Structures Sclera and cornea

Aqueous humor, iris, lens

Vitreous humor, retina, optic nerve

Fovea centralis, optic disc

Copyright © 2009 Pearson Education, Inc. Figure 12.14

Structure of the Eye

Canal ofSchlemm

IrisLens

Pupil

Cornea

Aqueoushumor

Ciliarymuscle

ScleraChoroid

Vitreoushumor

RetinaFovea

Opticdisk

Opticnerve

Copyright © 2009 Pearson Education, Inc. Table 12.4

Parts of the Eye and Their Function

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Regulating Light and Focusing

Focusing (continued) Eye shape

Normal shape allows focusing at fovea

Myopia: eye longer, nearsighted

Hyperopia: eye shorter, farsighted

Astigmatism: irregularities in cornea or lens

Copyright © 2009 Pearson Education, Inc. Figure 12.16a

Examples of Abnormal Vision

Copyright © 2009 Pearson Education, Inc. Figure 12.16b

Examples of Abnormal Vision

Copyright © 2009 Pearson Education, Inc. Figure 12.16c

Examples of Abnormal Vision

Copyright © 2009 Pearson Education, Inc. Figure 12.16d

Examples of Abnormal Vision

Copyright © 2009 Pearson Education, Inc. Figure 12.17

Structure of the Retina

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Disorders of Sensory Mechanisms

Disorders of the ear Deafness

Nerve

Conduction

Otitis media

Inflammation of the middle ear

Ménière’s syndrome

Inner ear condition impairs hearing and balance  

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Disorders of Sensory Mechanisms

Disorders of the eye Retinal detachment

Retina separates from choroid   Cataracts

Lens becomes opaque   Glaucoma

Pressure inside the eye rises   Color blindness

Inability to distinguish the full range of colors