35 Special Senses.

35 Special Senses

Learning Outcomes (cont.)
35.1 Describe the anatomy of the nose and the function of each part. 35.2 Describe the anatomy of the tongue and the function of each part. 35.3 Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions.

35.4 Explain the visual pathway through the eye and to the brain for interpretation. 35.5 Describe the causes, signs and symptoms, and treatments of various disorders of the eyes. 35.6 Describe the anatomy of the ear and the function of each part, and the role of the ear in maintaining equilibrium.

35.7 Explain how sounds travel through the ear and are interpreted in the brain. 35.8 Describe the causes, signs and symptoms, and treatments of various disorders of the ears.

Introduction Special senses – receptors in the head
Nose Tongue Eyes Ears Touch is a generalized sense Stimulus  nervous system  brain  response The special senses are smell, taste, vision, hearing, and equilibrium. These are special senses because their sensory receptors are located within relatively large sensory organs in the head. Touch is not considered a special sense but a generalized one. No matter how a stimulus starts, it is sent, via the nervous system, to the brain for interpretation and then reaction, if necessary.

The Nose and the Sense of Smell
Olfactory receptors Chemoreceptors – respond to changes in chemical concentrations Chemicals must be dissolved in mucus Located in the olfactory organ Learning Outcome: Describe the anatomy of the nose and the function of each part. Chemicals that activate smell receptors must be dissolved in the mucus of the nose. Smell receptors are located in the olfactory organ, found in the upper part of the nasal cavity. Chemicals must diffuse all the way up the nasal cavity in order to activate smell receptors.

The Nose and the Sense of Smell (cont.)
Activation of smell receptors  information sent to olfactory nerves The information is sent along olfactory bulbs and tracts Learning Outcome: Describe the anatomy of the nose and the function of each part. Smell receptors they send their information to the olfactory nerves. The olfactory nerves send the information along olfactory bulbs and tracts to different areas of the cerebrum. The cerebrum interprets the information as a particular type of smell. Sensory adaptation The same chemical can stimulate smell receptors for only a limited amount of time. The smell receptors fatigue and no longer respond to the same (odor) chemical, and it can no longer be smelled. Cerebrum – interprets information as a type of smell Sensory Adaption

Very Good! Apply Your Knowledge
You notice an odor coming from a patient when you enter the exam room. Why would the patient not be able to smell it? ANSWER: After a few minutes, smell receptors undergo sensory adaptation and no longer respond to the chemical, and the patient can no longer smell the odor. Learning Outcome: Describe the anatomy of the nose and the function of each part. Very Good!

The Tongue and the Sense of Taste
Gustatory receptors – on the taste buds Taste buds Papillae of the tongue Roof of mouth Walls of throat } fewer than on tongue Learning Outcomes: Describe the anatomy of the tongue and the function of each part. The taste buds are microscopic structures located on the papillae (bumps) of the tongue. Tongue

The Tongue and the Sense of Taste (cont.)
Taste buds Taste cells ~ chemoreceptors that react to chemicals in food and drink must be dissolved in saliva to activate Supporting structures ~ fill in space Learning Outcomes: Describe the anatomy of the tongue and the function of each part. The taste cells function as taste receptors, and the supporting cells simply fill in the spaces between the taste cells. Taste cells are types of chemoreceptors because they are activated by chemicals found in food and drink that must be dissolved in saliva as part of the digestive process. Tongue

Taste sensations Sweet – tip Sour – sides Salty – tip and sides Bitter – back Umami 5th basic taste Glutamate Spicy foods Activate pain receptors Interpreted by brain as “spicy” Learning Outcomes: Describe the anatomy of the tongue and the function of each part. There are four types of taste cells that are activated by a particular group of chemicals to produce the four primary taste sensations. Sweet – respond to “sweet” chemicals are concentrated at the tip of the tongue. Sour – respond to “sour” chemicals are concentrated on the sides of the tongue. Salty – respond to “salty” chemicals are concentrated on the tip and sides of the tongue. Bitter – respond to “bitter” chemicals are concentrated at the back of the tongue. In the 1980s, science recognized a taste known as umami. Glutamate is the substance responsible for this unique taste. Found most notably in tomatoes, and also in meats, fish, and dairy products. Tongue

Learning Outcomes: 35.2 Describe the anatomy of the tongue and the function of each part.
Back

Taste sensation Activation of taste cells Cranial nerves Learning Outcomes: Describe the anatomy of the tongue and the function of each part. Gustatory cortex is located in the parietal lobe of the cerebrum. Gustatory cortex of cerebrum interprets information as a particular taste

Apply Your Knowledge Great Job!
What are the four primary taste sensations and where are their corresponding taste cells located? ANSWER: The four primary taste sensations are: Sweet – concentrated on the tip of the tongue Sour – concentrated on the sides of the tongue Salty – concentrated on the tip and sides of the tongue Bitter – concentrated on the back of the tongue Learning Outcomes: Describe the anatomy of the tongue and the function of each part. Great Job!

The Eye and the Sense of Sight
Vision system Eyes Optic nerves Vision centers in the brain Accessory structures Eye Processes light to produce images Three layers Two chambers Specialized parts Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. The sense of sight comes from the eyes and is also supported by visual accessory organs. Accessory structures Eye orbits (sockets) Eyelids Conjunctivas Lacrimal apparatus Extrinsic eye muscles

The Eye and the Sense of Sight (cont.)
Outer Layer Sclera Tough outer layer Light cannot pass through the sclera Sense receptors Limbus ~ corneal-scleral junction Cornea Transparent “Window” that allows light into eye Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. Sclera – white of the eye Covers all except the front of the eye Gives way to cornea at the limbus No blood vessels Eye

Middle layer – choroid Contains blood vessels Iris Muscle tissue relaxes and contracts to alter the size of the pupil Regulates the amount of light entering the eye Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. The iris The colored part of the eye. Light regulation In bright light, the pupil constricts. In dim light, it dilates. Eye

Middle layer (cont.) Ciliary body ~ wedge-shaped muscles that controls the shape of the lens Lens Changes shape to focus light on retina Accommodation – the ability of the lens to change shape Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. The ciliary body A wedge-shaped thickening in the middle layer. Muscles control the shape of the lens, making the lens more or less curved for viewing either near or distant objects. The lens A clear, circular disk located just posterior to the iris. Accommodation – allows the eye to focus images of objects that are near by or far away. Eye

Inner layer – retina Optic disc – optic nerve enters retina Rods Sensitive to light Function in dim light – “night” and peripheral vision Do not provide sharp image or detect color Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. Nerve cells at the posterior of the retina sense light. Optic disk – no sensory nerves itself and is referred to as the blind spot. There are two types of nerve cells, each named for its shape – rods and cones Rods – only detect the colors of black, white, and shades of gray. Eye

Inner layer (cont.) Cones Function in bright light Sensitive to color and provide sharp images Enable differentiation of tones and hues of color Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. Cones – deficiencies in the number or types of cones are responsible for the various types of color blindness.

Anterior chamber of the eye Front of lens Filled with aqueous humor – nourishes and bathes anterior eye Posterior chamber Behind lens Contains vitreous humor – maintains shape of eyeball and keeps the retina flat Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. Each eyeball is divided into two chambers. The Anterior Chamber In front of the lens Filled with a watery fluid called aqueous humor which provides nutrients to and bathes the structures in the anterior chamber of the eyeball. When there is an accumulation of aqueous humor, a person develops glaucoma. The Posterior Chamber Behind the lens Filled with a very thick, jelly-like fluid called vitreous humor which keeps the retina flat and helps to maintain the eye’s shape. Eye

Vitreous chamber (posterior chamber) Pupil Limbus
Retina Choroid CN II (Optic) Optic disc Sclera Vitreous chamber (posterior chamber) Pupil Limbus Iris Cornea Anterior chamber Anterior Posterior Ciliary body Lens Back

Visual Accessory Organs
Eye orbits – form a protective shell around the eyes Eyebrows protect eyes Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. Eyebrows reduce the chances that sweat and direct sunlight will enter the eyes.

Visual Accessory Organs
Eyelids Skin, muscle, and connective tissue Blinking Prevents surface from drying out Keeps foreign material out of eye Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. Eyelids – the muscle in the eyelid is called the orbicularis oculi and is responsible for blinking and squinting. Blinking Prevents the mucus membrane surface of the eyeball from drying. A moist eyeball surface is much less likely to grow bacteria than a dry one is. Protects the eyes, keeping foreign material from entering the eyes with the assistance of the eyelashes.

Visual Accessory Organs (cont.)
Conjunctivas – produce mucus to keep the surface of the eyeball moist Lacrimal apparatus Lacrimal glands ~ produce tears Nasolacrimal ducts ~ drain tears into nose Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. Conjunctivas – mucous membranes that line the inner surfaces of the eyelids and cover the anterior surface of each eyeball The lacrimal apparatus Lacrimal glands Located on the lateral edge of each eyeball. Tears are mostly water but also contain enzymes that can destroy bacteria and viruses Tears also have an outer oily layer that prevents them from evaporating. Nasolacrimal ducts Located on the medial aspect of each eyeball Drain tears into the nose. When a person cries, the abundance of tears entering the nose produces the “runny nose” associated with crying.

Visual Accessory Organs (cont.)
Extrinsic eye muscles Six per eye Move the eye Levator palpebrae superioris (cut) Optic Nerve Inferior Rectus Trochlea Superior oblique Superior rectus Lateral rectus Inferior oblique Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. Extrinsic eye muscles: Skeletal muscles Each eyeball has six extrinsic eye muscles attached to it that move the eyeball superiorly, inferiorly, laterally, or medially

Out of Sight! Apply Your Knowledge ANSWER: Matching:
___ Middle layer of eye A. Lacrimal glands ___ Eye sockets B. Aqueous humor ___ Controls shape of lens C. Retina ___ Outer layer of eye D. Sclera ___ Anterior chamber E. Vitreous humor ___ Tears F. Ciliary body ___ Ability of lens to G. Choroid change shape H. Orbits ___ Posterior chamber I. Accommodation ___ Inner layer of eye H F D B A Learning Outcome: Describe the anatomy of the eye and the function of each part, including the accessory structures and their functions. I Out of Sight! E C

Visual Pathways Eye works like a camera
Light enters the eye through the lens Refraction – bending of light to focus it on the retina Projected upside down on the retina Learning Outcome: Explain the visual pathway through the eye and to the brain for interpretation. The eye works much like a camera. Light reflected from an object, or produced by one, enters the eye from the outside and passes through the cornea, pupil, lens, and fluids in the eye. Refraction – bending of light by the cornea, lens and fluids to focus it on the retina. An image of an object is carried by light patterns and projected upside-down on the retina in an eye. Refer to Table 35-1 The Functions of the Parts of the Eye

Visual Pathways Occipital lobe of cerebrum
Optic chiasm Image upside down on retina Image turned right-side up Occipital lobe of cerebrum Retina converts light to nerve impulse Optic nerve Learning Outcome: Explain the visual pathway through the eye and to the brain for interpretation. An image of an object is carried by light patterns and projected upside-down on the retina in an eye. The retina converts the light into nerve impulses which are transmitted along the optic nerve to the brain. The impulses cross the optic chiasm Half of what a person sees in the right eye is interpreted in the left side of the brain, and vice versa. The brain interprets these impulses, turns the image right-side up, and “develops” a picture of the object from which the light originally came. Refer to Table 35-1 The Functions of the Parts of the Eye

Apply Your Knowledge What is refraction and which part of the eye carries out refraction? ANSWER: Refraction is the bending of light that enters the eye to focus it on the retina. The cornea performs this function. Well done! Learning Outcome: Explain the visual pathway through the eye and to the brain for interpretation.

The Aging Eye Less adaptable to light Tears altered Eyes dryer
Impaired night and peripheral vision Impaired depth perception Tears altered Eyes dryer Lens more rigid Retinal changes Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the eyes. With age, a number of changes occur in the structure and function of the eye, including these. Quality and quantity of tears decrease. Conjunctiva thins and eyes may become dryer Lens become denser and more rigid Retinal changes – vision fuzzy Changes in ability of eye to adapt to light Impaired night and peripheral vision and depth perception See text for others. Refer to Educating the Patient: Preventing Falls in the Elderly

Common Diseases and Disorders
Disorder/Disease Description Astigmatism Cornea or lens has abnormal shape; blurred images Dry eye syndrome Results from a decreased production of the oil within the tears Ectropin Eversion of lower eyelid Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the eyes. Also refer to Educating the Patient: Eye Safety and Protection Astigmatism The cornea or lens has an abnormal shape causing blurred images during near or distant vision. Normally considered to be a congenital condition. Dry eye syndrome One of the most common eye problems Normally occurs with age Caused by cigarette smoke; air conditioning; eye strain created by long hours at a computer monitor; some medications; contact lenses; hormonal changes associated with menopause; and hot, dry, or windy climates. Ectropion Characterized by eversion (turning inside-out) of the lower eyelid Aging and skin relaxation or scar tissue

Common Diseases and Disorders
Disorder/Disease Description Entropion Inversion of lower eyelid Nystagmus Rapid, involuntary eye movements Retinal detachment Layers of retina separate; medical emergency Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the eyes. Entropion Characterized by an inversion (turning outside-in) of the lower eyelid. Aging and scar tissue may cause this condition. Nystagmus – causes include Alcohol and some drug use Inner ear disturbances Brain lesions and injury, and cerebrovascular accidents or strokes Retinal detachment – causes Fluids that seep between layers of the retina; this occurs most commonly in nearsighted people. In diabetics, vitreous body or scar tissue pulls the retina loose. Eye trauma that causes fluid to collect underneath the layers of the retina.

Nice job! Apply Your Knowledge
What vision changes can occur in the elderly patient? ANSWER: An elderly patient may have difficulty seeing because of drooping eyelids. Focusing may be more difficult because less light enters the eye. He may have difficulty distinguishing colors due to yellowing of the lens. Vision may be fuzzy because of changes in the retina. Night vision can become impaired. The patient may see floaters or “sparks.” Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the eyes. Nice job!

The Ear and Senses of Hearing and Equilibrium
External ear Auricle (pinna) - collects sound waves External auditory canal Lined with hairs and glands that produce cerumen Guides sound wave to the tympanic membrane which separates external ear and middle ear Learning Outcome: Describe the anatomy of the ear and the function of each part, and the role of the ear in maintaining equilibrium. The organ of hearing is the ear. Provides the sense of hearing Aids the body in maintaining balance, or equilibrium. The ear is divided into three parts – external ear, middle ear and inner ear. The external ear consists of: The auricle or pinna The flap of skin and cartilage that hangs off the side of the head. Functions to collect sound waves External auditory canal (ear canal) Lined with skin that contains hairs and glands that produce cerumen Cerumen lubricates the ear and protects it by trapping dirt, dust, and other microbes Tympanic membrane A fibrous partition located at the inner end of the external auditory canal Separates the external ear from the middle ear Ear

The Ear and Senses of Hearing and Equilibrium (cont.)
Middle ear Ear ossicles Malleus Incus Stapes Ossicles Vibrate Hit the oval window Learning Outcome: Describe the anatomy of the ear and the function of each part, and the role of the ear in maintaining equilibrium. Common names for ear ossicles Malleus – hammer Incus – anvil Stapes – stirrup Ossicles – vibrate in response to the vibration of the tympanic membrane. Ear

Middle ear (cont.) Eustachian tube Connects middle ear to throat Equalizes pressure on eardrum Oval window – separates middle ear from inner ear Learning Outcome: Describe the anatomy of the ear and the function of each part, and the role of the ear in maintaining equilibrium. Because the ear and throat are connected by the Eustachian tube, any infection of the throat can easily spread to the ear, and vice versa. Ear

Auricle (pinna) External Ear Middle Ear Inner Ear External ear canal Tympanic membrane Oval window Ossicles Stapes Incus Malleus Labyrinth Vestibule Cochlea Eustachian tube Back

Inner ear – labyrinth of communicating chambers Semicircular canals ~ equilibrium Vestibule ~ equilibrium Cochlea Hearing receptors Organ of Corti – organ of hearing Learning Outcome: Describe the anatomy of the ear and the function of each part, and the role of the ear in maintaining equilibrium. Labyrinth – a very complex system of communicating chambers and tubes that is divided into three portions Semicircular canals – three semicircular canals that function to detect the body’s balance Vestibule Between the semicircular canals and the cochlea It also functions in equilibrium When the head moves, the perilymph and endolymph fluids in the semicircular canals and vestibule move. The equilibrium receptors send the information along vestibular nerves to the cerebrum for interpretation. Cochlea shaped like a snail’s shell and contains hearing receptors, including the organ of Corti, which is known as the organ of hearing. When sound waves of different volumes and frequencies activate the hearing receptors they send their information to auditory nerves. Auditory nerves (vestibulocochlear nerves) deliver the information to the auditory cortex in the cerebrum’s temporal lobe. The auditory cortex interprets the information as sounds. Inner ear

Semicircular canals Cochlea Oval window Vestibule Cochlear nerve Back

Activates equilibrium and hearing receptors Fluid moves in semicircular canals and vestibule Head movement Learning Outcome: Describe the anatomy of the ear and the function of each part, and the role of the ear in maintaining equilibrium. 35.6 Explain the role of the ear in maintaining equilibrium. When the head moves, the perilymph and endolymph fluids in the semicircular canals and vestibule move. This activates both equilibrium and hearing receptors. The equilibrium receptors send the information along vestibular nerves to the cerebrum for interpretation. The cerebrum can then advise the body if it needs to make any adjustments to prevent a fall. Vestibular nerves transmit information Cerebrum interprets information and advises the body to make adjustments

Apply Your Knowledge Supear! ANSWER: Matching:
___ Pinna A. Organ of Corti ___ Malleus, incus, and stapes B. Cerumen ___ Hearing receptors C. Ear ossicles ___ Inner ear D. Tympanic membrane ___ Organ of hearing E. Auricle ___ Earwax F. Cochlea ___ Eardrum G. Labyrinth ___ Detect balance of body H. Semicircular canals C F G A Learning Outcome: Describe the anatomy of the ear and the function of each part, and the role of the ear in maintaining equilibrium. B D H

The Hearing Process External ear
Collect sound waves Channels waves to the tympanic membrane Tympanic membrane vibrates Middle ear – ossicles amplify vibrations Learning Outcome: 35.7 Explain how sounds travel through the ear and are interpreted in the brain. A sound consists of waves of different frequencies that move through the air. The external ear initiates sound conduction by collecting the waves and channeling them to the tympanic membrane. The waves cause the tympanic membrane to vibrate The vibrations are amplified by the middle ear’s ossicles.

The Hearing Process (cont.)
Inner ear Amplified waves bend hairs lining cochlea Movement of hairs trigger nerve impulses Impulses are transmitted by auditory nerve to the brain for interpretation Learning Outcome: 35.7 Explain how sounds travel through the ear and are interpreted in the brain. The vibrations are amplified by the middle ear’s ossicles and enter the inner ear and the cochlea. These amplified waves cause tiny hairs that line the cochlea to bend triggering nerve impulses. The auditory nerve transmits these impulses to the brain, where they are perceived as sound.

The Hearing Process (cont.)
Bone conduction Alternate sound pathway to inner ear Bones of the scull conduct sound waves Identification of hearing problems Normal bone conduction Problem likely in middle or external ear Learning Outcome: 35.7 Explain how sounds travel through the ear and are interpreted in the brain. Bone conduction is an alternative pathway for sound that bypasses the external and middle ears. Sound waves are conducted through the bones of the skull directly to the inner ear. When you hear your own voice, the sound has reached your inner ear mainly through bone conduction. By comparing a person’s ability to sense sounds by bone conduction and through the entire ear, doctors can often identify what part of the ear is causing a hearing problem

Apply Your Knowledge How do we hear? Great Answer!
ANSWER: Sound waves are collected by the external ear and are funneled down the ear canal to the tympanic membrane. The waves make the tympanic membrane vibrate. The ossicles amplify these vibrations which enter the inner ear and cause movements of the hairs that line the cochlea. These movements trigger nerve impulses which are sent to the brain via the auditory nerve. The brain perceives the impulses as sound. Learning Outcome: 35.7 Explain how sounds travel through the ear and are interpreted in the brain. Great Answer!

The Aging Ear External ear Middle ear
Larger Cerumen drier Canal narrows Middle ear Eardrum shrinks Joints between ossicles degenerates Inner ear – less sensitive to position changes Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the ears. As a person grows older, a number of changes occur in the ear. The external ear Appears larger because of continued cartilage growth and the loss of skin elasticity. The glands that produce cerumen become less efficient and earwax is much drier and prone to impaction. The ear canal also becomes narrower. In the middle ear Eardrum shrinks and appears dull and gray. Joints between the bones of the middle ear degenerate and do not move as freely The inner ear – the semicircular canals become less sensitive to changes in position and this reduced sensitivity affects balance. Problems with equilibrium make the elderly prone to falls. Some ear disorders, like hearing loss and Mèniére’s disease, are also more common in older individuals.

How to Recognize Hearing Problems in Infants
Infants to 4 months Startled by loud noises Recognize mother’s voice 4 to 8 months Regularly follow sounds Babble at people 8 to 12 months Respond to the sound of their name Respond to “no” Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the ears. Hearing problems in infants are not easy to recognize. These general guidelines can be used to teach parents how to identify normal hearing in infants. Any deviations from these guidelines may indicate a hearing loss. Infants up to 4 months When sleeping in quiet room, should wake up at sound of voices Around age 4 months, should turn their head or move their eyes to follow a sound Infants 4 to 8 months Facial expressions should change at sound of familiar voices or loud noises Begin to enjoy sounds such as rattles or ringing bells Babies 8 to 12 months Begin to vary the pitch of the sounds they produce with their babbling Begin to respond to music

Common Diseases and Disorders of the Ear
Disorder/Disease Description Acoustic Neuroma Benign tumor of the cranial nerve involved in hearing and balance; commonly causes gradual hearing loss in one ear Cerumen impaction Build up of wax within external auditory canal with some degree of hearing loss due to blocked sound waves Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the ears. Acoustic Neuroma – caused by a malfunction in a gene responsible for controlling the growth of Schwann cells (a type of neuroglial cell). Cerumen impaction – caused by Improper cleaning of cerumen from the ear canal, using cotton-tipped applicators Over-active ceruminous glands producing more than normal cerumen.

Common Diseases and Disorders of the Ear
Disorder/Disease Description Hearing loss Deafness; the loss of the ability to hear sounds at normal levels. Conductive – blockage of sound waves Sensorineural – damage to auditory nerve Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the ears. Hearing loss Conductive hearing loss – causes include cerumen impaction, a foreign body, otosclerosis (hardening of the stapes), or a tumor. Sensorineural hearing loss – causes may include infection, medications, head trauma, and vascular disorders. In some cases, both types of hearing loss may be evident.

Common Diseases and Disorders of the Ear (cont.)
Disorder/Disease Description Otitis Otitis externa Otitis media Otitis interna Inflammation of the ear Swimmers’ ear Middle ear infection; common infection Labyrinthitis; inner ear infection Osteosclerosis Immobilization of the stapes; common cause of conductive hearing loss Presbycusis Hearing loss due to aging process Learning Outcome: Describe the causes, signs and symptoms, and treatments of various disorders of the ears. Otitis Otitis externa – bacterial infections Otitis media – the spread of an upper respiratory infection from the throat that enters the Eustachian tube and infects the middle ear. Labyrinthitis, especially the purulent or infective type, occurs from a spread of otitis media to the inner ear. Otosclerosis – causes may be genetic; occurs more frequently in females than in males. Presbycusis – the auditory system deteriorates, resulting in a loss of hair cells in the organ of Corti.

Apply Your Knowledge Excellent! True or False:
ANSWER: Excellent! True or False: ___ Otitis media is also called swimmers’ ear. ___ Presbycusis is hearing loss due to the aging process. ___ Otitis interna is an inflammation of the labyrinth. ___ Otosclerosis is the immobilization of the stapes. Conductive hearing loss is caused by damage to the auditory nerve. Labyrinthitis often causes nausea and vertigo. externa F T T T Learning Outcome: 35.7 Explain how sounds travel through the ear and are interpreted in the brain. F Sensorineural T

In Summary 35.1 Olfactory receptors – the sense receptors for the sense of smell – are found in the olfactory organ located in the upper part of the nasal cavity. 31.2 Gustatory receptors are found on the taste buds, which are located on the papillae (bumps) of the tongue. 35.3 The eye is composed of three layers. The sclera is the outer protective layer and includes the cornea. The middle vascular layer is the choroid consisting of the iris, pupil, ciliary body, and lens, and is the area of light regulation and focusing. The innermost layer is the retina containing the rods and cones, the optic nerve, and the optic disk. This is where the nerve impulse is picked up and brought to the brain for interpretation. The accessory organs are the orbits, eyelids, conjunctivas, lacrimal apparatus, and extrinsic eye muscles, all of which are protective for the eye.

In Summary 35.3 The eye is composed of three layers. The sclera is the outer protective layer and includes the cornea. The middle vascular layer is the choroid consisting of the iris, pupil, ciliary body, and lens, and is the area of light regulation and focusing. The innermost layer is the retina containing the rods and cones, the optic nerve, and the optic disk. This is where the nerve impulse is picked up and brought to the brain for interpretation. The accessory organs are the orbits, eyelids, conjunctivas, lacrimal apparatus, and extrinsic eye muscles, all of which are protective for the eye.

In Summary (cont.) 35.4 The cornea, lens, and fluids focus light on the retina. The retina converts the image into nerve impulses that the optic nerve transmits to the brain for interpretation. 35.5 There are many common diseases and disorders of the eyes with varied signs, symptoms, and treatments. Some of these include astigmatism, dry eye syndrome, ectropion, entropion, nystagmus, and retinal detachment.

In Summary (cont.) 35.6 There are three parts to the ear. The external ear includes the auricle or pinna and the external auditory canal to the tympanic membrane. The middle ear begins at the tympanic membrane and ends at the oval window and includes the ear ossicles. The inner ear is composed of the labyrinth and contains the organ of Corti as well as perilymph and endolymph – the fluids of hearing. The semicircular canals and vestibule in the inner ear function in the body’s equilibrium and balance, sending impulses to the vestibular nerves, which bring information to the cerebrum for interpretation.

In Summary (cont.) 35.7 The outer ear collects sound waves and channels them to the tympanic membrane, which vibrates. The vibrations are amplified by the ear ossicles and enter the inner ear and cochlea. The movements of the hairs in the cochlea trigger nerve impulses that the auditory nerve transmits to the brain. 35.8 There are many common diseases and disorders of the ears with varied signs, symptoms, and treatments. Some of these include acoustic neuroma, cerumen impaction, hearing loss, otitis, otitis externa, otitis media, otitis interna, otosclerosis, and presbycusis.

End of Chapter 35 Every closed eye is not sleeping, and every open eye is not seeing. ~ Bill Cosby

35 Special Senses.

Similar presentations

Presentation on theme: "35 Special Senses."— Presentation transcript:

Similar presentations

About project

Feedback

Log in

Auth with social network:

35 Special Senses.

Similar presentations

Presentation on theme: "35 Special Senses."— Presentation transcript:

Similar presentations

About project

Feedback