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Chapter 11: The Sensory System
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Overview
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Key Terms accommodation glaucoma refraction
adaptation gustation retina astigmatism hyperopia sclera auditory tube iris semicircular canal aqueous humor lacrimal apparatus sensory adaptation cataract lens (crystalline lens) sensory receptor choroid macula spiral organ cochlea myopia strabismus conjunctiva olfaction tympanic membrane convergence ossicle vestibule cornea proprioceptor vitreous body
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The Senses Learning Outcomes
Describe the function of the sensory system. Differentiate between the different types of sensory receptors and give examples of each. Describe sensory adaptation and explain its value.
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The Senses Sensory system detects environmental change
Environmental change initiates nerve impulse (stimulus) Stimulus interpreted by cerebral cortex Sensation experienced
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The Senses Sensory Receptors
Receptor classification based on structure Free dendrite End-organ Specialized cell Receptor classification based on stimulus Chemoreceptor Photoreceptor Thermoreceptor Mechanoreceptor
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The Senses Special and General Senses Special Senses General Senses
Vision Pressure Hearing Temperature Equilibrium Pain Taste Touch Smell Sense of position
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The Senses Sensory Adaptation
Receptors often become less sensitive to a continuous unimportant stimulus.
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✓ The Senses Checkpoints 11-1 What is a sensory receptor? 11-2 What are some categories of sensory receptors based on type of stimulus? 11-3 How do the special and general senses differ in location? 11-4 What happens when a sensory receptor adapts to a stimulus?
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? The Senses Pop Quiz 11.1 Which of the following is a special sense?
A) Pressure B) Taste C) Touch Proprioception
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? The Senses Pop Quiz Answer
11.1 Which of the following is a special sense? A) Pressure B) Taste C) Touch Proprioception
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The Eye and Vision Learning Outcomes
List and describe the structures that protect the eye. Identify the three tunics of the eye. Define refraction and list the refractive parts of the eye. Differentiate between the rods and the cones of the eye. Compare the functions of the extrinsic and intrinsic eye muscles. Describe the nerve supply to the eye
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The Eye and Vision Protective Structures of the Eye Bony orbit Eyelids
Eyelashes Eyebrows Conjunctiva Lacrimal glands
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Figure 11-1 The eye’s protective structures.
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Figure 11-2 The lacrimal apparatus.
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The Eye and vision Structure of the Eyeball
Eyeball has three separate coats (tunics) Fibrous Tunic Vascular Tunic Nervous Tunic (retina) Sclera Choroid Rods Cornea Ciliary muscle Cones Suspensory ligaments Iris
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Figure 11-3 The eye. What anterior structure is
continuous with the sclera? 18
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The Eye and Vision Pathway of Light Rays and Refraction
Transparent parts of the eye that refract light Cornea Aqueous humor Crystalline lens Vitreous body
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The Eye and Vision Function of the Retina Rod cells
Function in dim light Shades of gray Blurred images Cone cells Function in bright light Color sensitive Sharp images
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Figure 11-4 Structure of the retina.
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Figure 11-5 The fundus (back) of the eye as seen through an ophthalmoscope.
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✓ The Eye and Vision Checkpoints 11-5 What are some structures that protect the eye? 11-6 What are the components of the three tunics of the eyeball? 11-7 What are the structures that refract light as it passes through the eye? 11-8 What are the receptor cells of the retina? 24
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? The Eye and Vision Pop Quiz
11.2 The middle, pigmented layer of the eye is the A) Sclera B) Conjunctiva C) Retina Choroid
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? The Eye and Vision Pop Quiz Answer
11.2 The middle, pigmented layer of the eye is the A) Sclera B) Conjunctiva C) Retina Choroid
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The Eye and Vision Muscles of the Eye
Adjust eye so retina receives clear image Extrinsic muscles Outer surface of eyeball Voluntary Control convergence for three-dimensional vision Intrinsic muscle Within eyeball Iris regulates amount of light entering eye Ciliary muscle shapes lens for near and far vision
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Figure 11-7 Function of the iris.
What muscles of the iris contract to make the pupil smaller? Larger? 28
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Figure 11-6 Extrinsic muscles of the eye.
What characteristics are used in naming the extrinsic eye muscles? 29
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Figure 11-8 The ciliary muscle and lens (posterior view).
What structures hold the lens in place? 30
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Figure 11-9 Accommodation for near vision.
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The Eye and Vision Nerve Supply to the Eye Sensory Optic nerve (CN II)
Ophthalmic branch of trigeminal nerve (CN V) Motor Oculomotor nerve (CN III) Trochlear (CN IV) Abducens (CN VI)
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Figure 11-10 Nerves of the eye.
Which of the nerves shown controls eye movement? 33
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The Eye and Vision Disorders of the Eye and Vision
Errors of refraction Hyperopia Myopia Astigmatism Strabismus Convergent Divergent Amblyopia
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The Eye and Vision Disorders of the Eye and Vision Infections
Conjunctivitis Inclusion conjunctivitis Opthalmia neonatorum Injuries Cornel laceration Enucleation
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The Eye and Vision Disorders of the Eye and Vision Cataract Glaucoma
Retinal disorders Diabetic retinopathy Retinal detachment Macular degeneration
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Figure 11-11 Errors of refraction.
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Figure 11-12 Retinal disorders.
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✓ The Eye and Vision Checkpoints 11-9 What is the function of the extrinsic eye muscles? What is the function of the iris? What is the function of the ciliary muscle? What is cranial nerve II and what does it do? What are some errors of refraction? 40
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? The Eye and Vision Pop Quiz
11.3 Which of the following is an intrinsic eye muscle? A) Iris B) Lateral rectus C) Superior rectus Suspensory ligament
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? The Eye and Vision Pop Quiz Answer
11.3 Which of the following is an intrinsic eye muscle? A) Iris B) Lateral rectus C) Superior rectus Suspensory ligament
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The Ear Learning Outcomes Describe the three divisions of the ear.
Describe the receptor for hearing and explain how it functions. Compare the location and function of the equilibrium receptors.
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The Ear Sense organ for hearing and equilibrium Components Outer ear
Middle ear Inner ear
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The Ear The Outer Ear Structure Pinna External auditory canal
Ceruminous glands Tympanic membrane Function Collect sound waves and transmit sounds to middle ear
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Figure The ear. What structure separates the outer ear from the middle ear? 46
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The Ear Middle Ear Structure Ear ossicles Malleus Incus Stapes
Auditory tube Function Amplifies sound waves and transmit sounds to inner ear
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Figure The ear. What structure separates the outer ear from the middle ear? 48
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The Ear Inner Ear Structure Bony labyrinth; contains perilymph
Divisions Vestibule Semicircular canals Cochlea Membranous labyrinth; contains endolymph Function Transduce sound waves into nerve impulses
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Figure The ear. What nerve is formed by the merger of the nerves from the inner ear? 50
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Figure 11-15 Cochlea and the spiral organ.
Which part of the cochlea contains the spiral organ? 51
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The Ear The Steps in Hearing Sound waves enter external auditory canal
Tympanic membrane vibrates Ossicles transmit vibrations across middle ear Stapes transmits vibrations at oval window to inner ear fluid
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The Ear The Steps in Hearing (continued)
Vibrations travel through perilymph of bony labyrinth Spiral organ’s hair cells vibrate against tectorial membrane, generating nerve impulses Impulses travel via cochlear nerve to temporal lobe cortex, where they are interpreted Sound waves leave inner ear through the round window
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The Ear Equilibrium Ciliated equilibrium sensory receptors are located in vestibule and semicircular canals. Types of Receptors Maculae Cristae Nerve supply via vestibular nerve
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Figure 11-16 Action of the vestibular equilibrium receptors (maculae).
What happens to the cilia of the macular cells when the fluid around them moves? 55
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Figure 11-17 Action of the equilibrium receptors (cristae) in the semicircular canals.
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The Ear Disorders of the Ear Ear infection Otitis media Otitis externa
Hearing loss Conductive hearing loss Sensorineural hearing loss Presbycusis Equilibrium disturbances Vertigo
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✓ The Ear Checkpoints What are the ossicles of the ear and what do they do? What is the name of the organ of hearing and where is it located? Where are the receptors for equilibrium located? What are the two types of hearing loss? 59
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? The Ear Pop Quiz 11.4 The ear ossicle that is in contact with the tympanic membrane is the A) Malleus B) Incus C) Meatus Stapes
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? The Ear Pop Quiz Answer 11.4 The ear ossicle that is in contact with the tympanic membrane is the A) Malleus B) Incus C) Meatus Stapes
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Other Special Sense Organs
Learning Outcome Discuss the location and function of the special sense organs for taste and smell.
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Other Special Sense Organs
Taste and smell sense organs respond to chemical stimuli.
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Other Special Sense Organs
Sense of taste (gestation) Receptors (taste buds) Sweet Salty Sour Bitter Umami Nerve supply Facial nerve Glossopharyngeal nerve
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Other Special Sense Organs
Sense of smell (olfaction) Receptors in upper nasal cavity Nerve supply via olfactory nerve
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Sense of Smell Smell receptors in nasal cavity
Stimulated by substances in solution in nasal fluids Smells stimulate appetite and flow of digestive juices Olfactory nerve (cranial nerve I)
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Figure 11-18 Special senses that respond to chemicals.
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✓ Other Special Senses Checkpoint What are the special senses that respond to chemical stimuli? 68
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The General Senses Learning Outcomes
Explain the function of proprioceptors. List several methods for treatment of pain.
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The General Senses Receptors scattered throughout the body sense Touch
Pressure Heat Cold Position Pain
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The General Senses Sense of Pain Pain receptors Are free nerve endings
Are found in skin, muscles, joints and (to a lesser extent) in most internal organs Pain relief Analgesic drugs Anesthetics Endorphins Heat or cold Relaxation or distraction techniques
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Sensory Adaptation Occurs when receptors are exposed to continuous stimulus Some receptors can adjust themselves so sensation becomes less acute. Receptors adapt at different rates. Pain receptors do not adapt.
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Figure 11-19 Sensory receptors in the skin.
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✓ The General Senses Checkpoints What are examples of general senses? What are proprioceptors and where are they located? 74
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? The General Senses Pop Quiz
11.5 If you hold your arm motionless in the air, which receptors are most important in informing you of your hand position? A) Proprioceptors B) Pressure receptors C) Tactile corpuscles Free nerve endings
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? The General Senses Pop Quiz Answer
11.5 If you hold your arm motionless in the air, which receptors are most important in informing you of your hand position? A) Proprioceptors B) Pressure receptors C) Tactile corpuscles Free nerve endings
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Case Study Learning Outcome
16. Using the case, discuss changes in the anatomy and physiology of the eye resulting from chronic sun exposure. 77
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Word Anatomy Learning Outcome
17. Show how word parts are used to build words related to the sensory system. 78
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Word Anatomy Word Part Meaning Example ophthalm/o eye
An ophthalmologist is a physician who specializes in treatment of the eye. presby- old Presbyopia is farsightedness that occurs with age. tympan/o drum The tympanic membrane is the eardrum. ot/o ear Otitis is inflammation of the ear. propri/o own Proprioception is perception of one’s own body position. alges/i pain An analgesic is a drug that relieves pain.
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