Introduction to Health ScienceIntroduction to Health ScienceSpecial SensesSpecial Senses

Vocabulary- combining formsVocabulary- combining forms

• Acous/ohearing

• Audit/ohearing

• Blephar/o eyelid

• Conjunctiv/oconjunctiva

• Dacry/o tear

• Dipl/o double

• Gloss/o tongue

• Kerat/o horny tissue/ cornea

• Lacrim/o tear

• Ocul/o eye

• Ophthalm/o eye

• Opt/o eye/ vision

• Ot/o ear

• Scler/o sclera/ white

of the eye

• Retin/o retina

• Tympan/o ear drum / tympanic membrane

Vocabulary- prefixes & suffixesVocabulary- prefixes & suffixes

• Intra- within

• -ar pertaining to

• -ic pertaining to

• -ory pertaining to

• -tic pertaining to

• -al pertaining to

• -algia pain

• -dynia pain

• -itis inflammation

• --logist specialist

• -logy study of

• -scope instrument to view

• -scopy visual examination

• -pathy disease

• -plastysurgical repair

• -spasm involuntary contraction

• -rrhea flow or discharge

• -opia vision

• -tomy incision

VocabularyVocabulary• ENT ear, nose, throat

• Olfactory pertaining to smell

• Auditory pertaining to hearing

• Gustatory pertaining to taste

• Lacrimal pertaining to tears

• Ossicles bones of the middle ear

Types of ReceptorsTypes of Receptors• The special senses work with specialized

neurons or receptors. There are three different types that respond to different things.

• Chemoreceptors respond to chemicals

• Photoreceptors respond to light

• Mechanoreceptors respond to movement

SmellSmellSmell occurs when specialized cells in the nose Smell occurs when specialized cells in the nose (chemoreceptors) detect chemicals resulting in (chemoreceptors) detect chemicals resulting in nerve impulses which are sent to the brain for nerve impulses which are sent to the brain for interpretation.interpretation.

NoseNose• In the upper part of the nasal cavity are specialized nerve cells In the upper part of the nasal cavity are specialized nerve cells

called olfactory receptor cells. The olfactory receptor cells called olfactory receptor cells. The olfactory receptor cells contain hair called cilia to which the dissolved chemicals contain hair called cilia to which the dissolved chemicals attach.attach.

• Nerve impulses are transmitted from the olfactory receptors Nerve impulses are transmitted from the olfactory receptors cells to the olfactory bulb, to the olfactory nerve, to the brain cells to the olfactory bulb, to the olfactory nerve, to the brain where the sense of smell is interpreted.where the sense of smell is interpreted.

• Basic smells include:Basic smells include:• putrid (rotting food)putrid (rotting food)• pungent (spicy)pungent (spicy)• floral (flowers)floral (flowers)• ethereal (medicine smell)ethereal (medicine smell)• mintmint

TasteTaste• Taste occurs when specialized cells on the

tongue (chemoreceptors) detect chemicals resulting in nerve impulses which are sent to the brain for interpretation.

Mouth and TongueMouth and Tongue• The sense organs that detect dissolved chemicals for the

sense of taste are the taste buds. Taste buds are located in the tongue and throughout the mouth.

• When the taste buds are stimulated by chemicals, they generate nerve impulses which are sent to the brain for interpretation.

• There are five basic tastes, although they are not limited to specific parts of the tongue: – sweet (sugars and carbohydrates)– sour (acids)– salt – bitter – umami (protein and amino acids)

HearingHearing• Hearing involves the movement of sound

vibrations through the ear until they reach a specialized region in the inner ear where nerve impulses are generated by cells that detect movement (mechanoreceptors). These nerve impulses travel to the brain where they are interpreted as sound.

Parts of the EarParts of the Ear• The Ear has three sections– The outer ear• Auricle or pinna• External auditory canal

– The middle ear• Tympanic membrane• Eustachian tube• Ossicles• Oval window

– The inner ear• Cochlea• Vestibule

Outer EarOuter Ear• Auricle (or Pinna)– The visible portion of the ear on the side of the head.– Composed of cartilage – Captures the sound waves from the environment and

directs them toward the auditory canal.

• Auditory Canal– Tube lined with hair and wax.– Assists in the passage of sound waves to the middle

ear.– Provides protection for the ear as particles, debris and

dust are trapped by the hair and wax.

Middle EarMiddle Ear• Tympanic Membrane– Known as the eardrum, it is the first structure of

the middle ear.– It vibrates with the sound waves and passes the

vibrations to the middle ear bones.

• Eustachian Tube (auditory tube)– Small tube extending from the middle ear into the

throat.– Helps to equalize pressure inside the ear.

Middle EarMiddle Ear• Auditory Ossicles – Three tiny bones in the middle ear that continue

the passage of sound vibrations.• Malleus (hammer)• Incus (anvil)• Stapes (stirrup)

– They amplify the vibrations twenty times.– Transfer force through the oval window to the

cochlea

Inner EarInner Ear• Cochlea • Snail shaped structure composed of a series of

membrane-lined fluid-filled canals that continue to pass along the sound vibrations.

• Organ of Corti• The sound vibrations eventually reach a

specialized structure of the inner ear called mechanoreceptors where nerve impulses are generated. The impulses are transmitted to the brain where they are interpreted.

Inner Ear- balanceInner Ear- balance• dynamic equilibrium - interprets balance when

one is moving– Semicircular Canals

• static equilibrium - interprets the position of the head to maintain stability and posture when the head and body are not moving– Vestibule

Inner Ear-balanceInner Ear-balance• Semicircular Canals:– A series of membrane-lined fluid-filled canals– Are the body's balance organs, detecting motion

in the three perpendicular planes.

• Vestibule:– Contains the saccule and utricle – Work with the eyes to maintain postural balance

TouchTouch• Touch is the detection of various amounts of

pressure by the skin. • Nerve impulses are generated by cells that are

sensitive to movement (mechanoreceptors) and sent to the brain for interpretation.

VisionVision• The sense organs that respond to light are the

eyes. • The light waves travel through the eyes until

they reach the back of the eye called the retina where nerve impulses are generated by specialized cells that are sensitive to light (photoreceptors).

• The impulses travel to the brain where they are interpreted as visual images and provide much information about the external world.

EyeEye• Eyelid– Structures composed of skin, muscles, and lashes– Protect the eye from foreign objects by the blink

reflex.– Moves tears along the surface of the eyeball to

keep the eyeball moist.

• Conjunctiva– Membrane lining the insides of the eyelids and

eyeball.– Reduces friction during blinking

EyeEye• Sclera– The white part of the eye.– Provides protection and shape to the eye.

• Cornea– The clear window in the front part of the eye.– Allows light waves to enter the eye.– Helps to bend the light waves on to the back of

the eye (retina)

EyeEye• Iris– The colored portion of the eye which contains two

sets of muscles.– Regulates the size of the pupil to control the amount

of light entering the eye.• Pupil– An opening in the center of the iris.– Passage for light.

• Lens– Transparent disc shaped structure located behind the

iris and pupil.– Focuses light waves onto the retina.

EyeEye• Retina– Most inner layer of the eyeball. Located under the

sclera.– Contains the photoreceptors that when stimulated

by light generate nerve impulses which are then sent to the brain for interpretation.– Rods see black and white (most active in low light)– Cones see color (blue, green, red) (most active in bright

light)* Macula Lutea is an area in the very back of the eye

which has a depression called the Fovea Centralis that contains only cones and allows for high visual acuity

Optic NerveOptic Nerve• This is the cranial nerve that takes information

from the eye to the occipital lobe of the cerebrum to be processed

• Where the optic nerve attaches to the eye, the retina has no rods or cones

ConjunctivitisConjunctivitis– Conjunctivitis is the

inflammation of the conjunctiva.

– Can be caused by viruses, bacteria, fungi, and allergies. The most common cause is viral.

– ”Pinkeye” is the common term for conjunctivitis.

– Treatment usually includes topical or oral medication

TinnitusTinnitus• Tinnitus is the term used for any ear noise when Tinnitus is the term used for any ear noise when

there is not outside source for the sounds. there is not outside source for the sounds. • Is common. Most people have experienced it – and Is common. Most people have experienced it – and

it only lasts for a few minutes. it only lasts for a few minutes. • Causes are unknown but may be associated with an Causes are unknown but may be associated with an

ear infection, ear injury, and as a reaction to various ear infection, ear injury, and as a reaction to various drugs including alcohol, caffeine, antibiotics and drugs including alcohol, caffeine, antibiotics and aspirin. aspirin.

• Also known as ringing in the ears. Also known as ringing in the ears. • Treatment depends on the causeTreatment depends on the cause

VertigoVertigo

• Also known as dizziness, light headedness, or a feeling that the room is spinning or moving.

• Occurs when:– there is not enough blood

to the brain – changing the position of

the head – a viral infection of the inner

ear – or Meniere’s disease (an

inner ear disease).

• Treatment can be physical therapy or medications

Middle Ear Infection (Otitis Media)Middle Ear Infection (Otitis Media)• Causes of otitis media include

anything that causes the Eustachian (auditory) tubes to become blocked, inflamed or irritated.– Examples include colds, sinus

infections, allergies, tobacco smoke or other irritants, babies who spend a lot of time drinking on his or her back.

• Most common symptom is earache

• Treatment includes antibiotics for bacterial infections, use of warm cloths and analgesics to relieve pain and possible surgery if ear infections recur frequently.

DeafnessDeafness

• Deafness is the complete or partial loss of hearing in one or both ears.

• May be caused by a blockage of the sound waves through the middle ear by wax build up, foreign objects, tumors or other matter. – This type of deafness generally improves

once the blockage is removed. • Deafness may also result from damage to

the nerves or to the Organ of Corti. – This type of deafness is usually irreversible

and may progressively get worse.• Treatment may include removal of the

blockage, hearing aids, or cochlear implants.

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MyopiaMyopia

• Nearsightedness; when a person sees near objects clearly and distant objects are blurred.

• Occurs when the physical length of the eye is greater than the optical length.

• Symptoms include blurred vision of distant objects, squinting, eyestrain, and sometimes headaches.

• Treated with concave lenses or LASIK surgery

HyperopiaHyperopia

• Farsightedness; when a person sees far objects clearly and near objects are blurred.

• Occurs when the physical length of the eyeball is too small or the focusing power of the lens is too weak.

• Symptoms include blurred vision of close objects, eye strain, aching eyes, and headaches while reading.

• Treated with convex lenses. Surgical options also available.

PresbyopiaPresbyopia• The normal loss of accommodation

power of the eye which occurs as a consequence of aging. It occurs because the lens becomes less flexible and less able to bulge or accommodate for near vision.

• Symptoms are similar to those of farsightedness and include:– blurring of close objects– eye strain – holding objects further from the face to

focus– headaches or fatigue from focusing on

close objects. • Treatments may include the use of

reading glasses or bifocals.