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Chapter 13 – General Sensory Receptors

Chapter 15 - Special Sensory Receptors

Lecture 22

Marieb’s HumanAnatomy and

Physiology

Marieb Hoehn

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Lecture Overview

• Introduction to the senses and sensation

• Types of sensors

• Classification of sensory receptors

• Anatomy of the ear

• Physiology of hearing/equilibrium

• Anatomy of the eye

• Physiology of vision

Video 1

Video 2

Video 3

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Special Senses

• sensory receptors are within large, complex sensory organs in the head

• hearing and equilibrium in ears• sight in eyes• smell in olfactory organs• taste (gustation) in taste buds

(Video 2)*

(Video 3)

Not covered in video – see master slide set

Overview of the Ear

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External Ear

• auricle (pinna)• collects sounds waves

• external auditory meatus

• lined with ceruminous glands• carries sound to tympanic membrane• terminates at tympanic membrane

• tympanic membrane • vibrates in response to sound waves

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The Middle Ear (Tympanic Cavity)

Typanic (attenuation) reflex: Elicited about 0.1 sec following loud noise; causes contraction of the tensor tympani m. and stapedius m. to dampen transmission of sound waves

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Auditory Tube

• Eustachian, auditory, or pharyngotympanic tube

• connects middle ear to throat

• helps maintain equal pressure on both sides of tympanic membrane

• usually closed by valve-like flaps in throat

When pressure in tympanic cavity is higher than in nasopharynx, tube opens automatically. But the converse is not true, and the tube must be forced open (swallowing, yawning, chewing).

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Inner Ear

3 Parts of Labyrinth• cochlea

• functions in hearing• semicircular canals

• function in equilibrium

• vestibule• functions in equilibrium• utricle and saccule

Labyrinth

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Cochlea

Scala tympani• lower compartment• extends from apex of the cochlea to round window• part of bony labyrinth

Scala vestibuli upper compartment leads from oval window to apex of spiral part of bony labyrinth

Cochlea as it would look ‘unwound’

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Organ of Corti

• group of hearing receptor cells (hair cells)• on upper surface of basilar membrane• different frequencies of vibration move different parts of basilar membrane• particular sound frequencies cause hairs (stereocilia) of receptor cells to bend• nerve impulse generated

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Physiology of Hearing

Know pathway for exam

Tympanic membrane malleus incus stapes oval window scala vestibuli scala tympani round window

Figure from: Marieb, Human Anatomy & Physiology, Pearson, 2013

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Auditory Nerve Pathways

Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004

(pons)

Accessory Nerve (CN XI)

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Vestibule

• Utricle• communicates with saccule and membranous portion of semicircular canals

• Saccule• communicates with cochlear duct

• Macula• contains hair cells of utricle (horizontal) and saccule (vertical)

Utricle and saccule provide sensations of: 1) gravity and 2) linear acceleration

These organs function in static equilibrium (head/body are still)

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Macula

• responds to changes in head position• bending of hairs results in generation of nerve impulse

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Semicircular Canals

• three canals at right angles

• ampulla (expansion) • swelling of membranous labyrinth that communicates with the vestibule

• crista ampullaris• sensory organ of ampulla• hair cells and supporting cells• rapid turns of head or body stimulate hair cells

Acceleration of fluid inside canals causes nerve impulse

These organs function in dynamic equilibrium (head/body are in motion)

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Crista Ampullaris

Semicircular canals respond to rotational, nonlinear movements of the head

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Pathways for Equilibrium Sensations

Figure from: Martini, Fundamentals of Anatomy & Physiology, Benjamin Cummings, 2004

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For vestibulo-ocular reflex

Please Take the Short Quiz

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Remember to take the brief quiz now to see if you’ve gotten the major concepts from the video.

You can always go back and review the video as many times as you like – and can retake the quiz, as well.