Special Senses

A&P CHAPTER 10

Special Senses

Touch Taste Smell Hearing Vision

Sensory Receptors

Structures that are stimulated by changes in the environment Receptors for touch, pain, temperature, pressure Found all over the body in all types of tissue ◦ Skin ◦ ◦ Connective Tissue Muscle

Sensory Receptors

Specific receptors ◦ Taste buds of the tongue ◦ ◦ ◦ Nose Retina of the eye Inner ear Projection of Sensation ◦ Sense organ is stimulated  travels along nerves to brain  sensation back to sense organ registers in the brain  brain sends ◦ Sensation actually takes place in brain

The Eye

Protected by: ◦ Orbital socket ◦ Eyebrows ◦ ◦ Eyelids Eyelashes Lacrimal Duct & Glands ◦ Cleanse & Moisten Oil Glands ◦ Secretes oily substance that lubricates the eye Conjunctiva ◦ Thin membrane lining the eyelids & part of the eye ◦ Secretes mucus to help lubricate the eye

The Wall of the Eye

Three Layers ◦ Sclera: Outer layer of the eye, known as the whites of the eye ◦ ◦ Choroid: Middle layer, contains blood vessels Retina: Innermost layer, image is perceived & impulses sent to the brain

The Eye

SCLERA Fibrous capsule that maintains the shape of the eye Protects structure within the eye Eye muscles attached to sclera ◦ Extrinsic Muscles CORNEA Clear, circular area that lies in front center of sclera “Window” of the eye Transparent to permit passage of light rays Pain & touch receptors

The Eye

CHOROID COAT Contain blood vessels that nourish the eye Pupil: Circular opening within the choroid coat IRIS Colored, muscular layer that surrounds the pupil Eye color is related to number & size of melanin in iris Intrinsic muscles in iris controls amount of light entering the pupil

The Eye

LENS Crystalline structure located behind the iris & pupil Elastic, disc shaped structure Focuses images on retina RETINA Light sensitive layer Location where light rays from an object form an image Rods ◦ Specialized cell sensitive to dim light Cones ◦ Specialized cell sensitive to bright light & color vision

Pathway of Vision

Images in the light  cornea cones pick up stimulus   pupil  optic nerve  lens  light rays are bent/refracted  occipital lobe of brain for interpretation retina  rods &

Eye Disorders

Conjunctivitis (Pink Eye) ◦ Inflammation of the conjunctival membranes ◦ ◦ Redness, pain, swelling, discharge of mucus Bacterial Conjunctivitis Highly contagious Glaucoma ◦ Excessive intraocular pressure  destruction of retina & atrophy of optic nerve ◦ ◦ Mild aching, loss of peripheral vision, halo around light Occurs with aging Cataracts ◦ Lens of eye gradually becomes cloudy ◦ ◦ Painless, gradual blurring & loss of vision; pupil will appear milky white Common in individuals over 70

Eye Disorders

Macular Degeneration ◦ Disorder of the retina ◦ Dimming/Distortion of vision ◦ Occurs as a person ages Detached Retina ◦ Loss of peripheral vision and then loss of central vision ◦ Can occur with age or from a traumatic accident Diabetic Retinopathy ◦ Leading cause of blindness in American adults ◦ Caused by changes in blood vessels in the retina Sty ◦ Tiny abscess (inflammation of sebaceous gland) at the base of an eyelash ◦ Red, painful, swollen ◦ Warm, wet compresses to relieve pain & promote drainage

Vision Defects

Night Blindness ◦ Difficult to see at night, rods are affected Color Blindness ◦ Inability to distinguish colors, cones are affected, inherited Presbyopia ◦ Lenses lose elasticity due to age  decreases ability to focus on close objects ◦ Common after 40, can be corrected with glasses/contacts Hyperopia ◦ Farsightedness Myopia ◦ Nearsightedness

Effects of Aging on the Eye

Decreased ability to focus on fine detail Slower to adjust to changing light conditions Peripheral vision and depth perception decline Loss of visual acuity

The Ear

Picks up sound waves & sends to the auditory center of the brain Involved in Equilibrium Three parts ◦ Outer/External ◦ ◦ Middle Inner

Outer Ear

Pinna (Outer part of ear) ◦ Collects sound waves ◦ Directs sound waves to auditory canal Auditory canal ◦ Glands secrete cerumen (earwax) to protect the ear Tympanic Membrane (Eardrum) ◦ Separates the outer and middle ear

Middle Ear

Cavity in the temporal bone Connects with pharynx (throat) through the Eustachian tube ◦ Eustachian tube is responsible for equalizing the air pressure in the middle ear with the outside atmosphere Three Tiny Bones are found in the Middle Ear ◦ Responsible for transmitting sound waves from eardrum to inner ear ◦ ◦ ◦ Hammer (Malleus) Anvil (Incus) Stirrup (Stapes)

Inner Ear

Cochlea ◦ Spiral-shaped passage, contains the cochlear duct Cochlear Duct ◦ Filled with fluid that vibrates when sound waves strike against it Organ of Corti ◦ Delicate hair-like cells located in the cochlear duct ◦ ◦ Pick up vibrations caused by sound waves against fluid Transmit vibrations through the auditory nerve to the brain Semi-Circular Canals (Three) ◦ Help maintain body balance/equilibrium ◦ No role in the sense of hearing

Ear Disorders

Otitis Media ◦ Middle Ear Infection Otosclerosis ◦ Stapes first becomes spongy, then hardens. Stapes become immovable.

◦ Inherited, common cause deafness among young adults Tinnitus ◦ Ringing in the ears due to injured auditory cells Presbycusis ◦ Hearing loss related to aging; Hearing aids can be used Meniere’s Disease ◦ Condition affecting the semicircular canals of the inner ear, causing vertigo (dizziness)

Effects of Aging

Tympanic membrane becomes fibrous ◦ Reduces the transmission of sound Degeneration of ear bones, vestibular structure, cochlea, organ of Corti ◦ Affects sensitivity to sound, understanding speech, and balance Loss of hearing high-pitched sounds Speech of others sounds garbled

The Nose

Smell accounts for about 90% of what we think we taste Receptors ◦ Olfactory Epithelium ◦ ◦ ◦ ◦ Patch of tissue in the nose About the size of a postage stamp Plentiful supply of nerve cells with specialized receptors Our nose can detect about 10,000 different smells!

Olfactory Nerve ◦ Transmits stimulus to brain

Disorders of the Nose

Nasal Polyps ◦ Growth inside the nasal cavity ◦ ◦ Usually associated with rhinitis If obstructive, may require surgery Deviated Nasal Septum ◦ Condition which there is a bend in the cartilage structure of the septum ◦ ◦ Symptoms include blockage of airflow in one nostril, snoring, nose bleeds, difficulty sleeping Surgical intervention may be required

The Tongue

Mass of muscle tissue Papillae ◦ Taste buds ◦ Sweet, Sour, Salty, Bitter Three cranial nerves transmit stimuli from taste buds to the brain for interpretation

Career Spotlight: Audiologist

Diagnose & Treat hearing problems, including balance disorders. Use technology to treat hearing disorders, including hearing aids and programming cochlear implants.

Work Settings: Schools, hospitals, private practice, research agency Yearly Salary: $52,000-90,000 Job Outlook: Excellent Education: Doctoral Degree

Career Spotlight: Ophthalmic Lab Technician

Make prescription eyeglasses and contact lenses.

Cut, grind, edge, and finish lenses according to orders from opticians, optometrists, and ophthalmologists.

Often use automated equipment to make lenses.

Work Settings: Labs, workshops, large eyeglass stores. Limited contact with people. Yearly Earnings: $18,860-43,250 Job Outlook: Excellent Education: On the job training

Career Spotlight: Dietary Aide

Works in food preparation and food service programs.

Yearly Earnings: $29, 200 Education: High school diploma and on the job training, certificate programs Prepare meals, plan menus, interview patients about their diets.

Work Settings: Hospitals, Long Term Care Facilities

Career Spotlight: Patient Advocate/Navigator

Trained, healthcare workers (often nurses) who provide support and guidance throughout the patient’s healthcare process.

Help navigate through appointments, insurance systems, patient support organizations, patient research, community outreach and other components. Yearly Earnings: Varies by background Job Outlook: Good Education: Varies by individual facility policies; often it is a RN or Social Worker which requires an associate’s degree or bachelor’s degree respectively. Work Setting: Hospital, Physicians Office

The END!