The Sensory Systems 7 Lesson 7.1: The Eye Lesson 7.2: The Ear Lesson 7.3: Smell and Taste

Chapter 7: The Sensory Systems Lesson 7.1 The Eye

The Eye anatomy of the eye (1” in diameter) vision External- eyebrows, eyelashes, etc internal vision injuries, diseases, and disorders of the eye

External Structures of the lubrication of the Eye tarsal glands- oil ciliary glands-mod sweat glands in lashes Conjunctiva-externa+mucous lacrimal glands- excretory ducts.

Extrinsic Muscles

Internal Structures of the Eye Humors- maintain shape Aqueous- anterior Vitreous- posterior tissue layers – there are 3 Sclera- outer (white part) Cornea- “window”, no blood supply

Internal Structures of the Eye Choroid- middle, vascular, pigmented layer (to prevent reflection) Pupil- opening Iris- color, lens of a camera- 2 muscles (sphincter and dilator pupillae) anterior to lens->convex and held by suspensory ligaments to focus light. Attached to cilliary body (part of Choroid) Retina- inner, posterior only layer, nerve endings that connect to optic nerve Rods- dim light, Cones- bright light, color, Optic Disc- “blind spot” between O. nerve and eye- no rods or cones

Internal Structures of the Eye

Vision retina impulse optic nerve brain optic chiasma optic tracts occipital lobe

Vision Disorders

Eye Diseases conjunctivitis Cataracts Glaucoma also known as pink eye- redness, pain, swelling, mucous Contagious bacterial infection Cataracts Clouding of lens, “halos” usually >70 years Sped up with exposure to bright sunlight Glaucoma Increased pressure of the eye- aqueous humor Loss of peripheral vision first, but can cause full blindness treat with medication and/ or surgery

Eye Diseases macular degeneration diabetic retinopathy Central vision only, dry (thinning of retina- no full loss of vision) or wet (vascular leakage of vessels of the eye- surgical intervention necessary) diabetic retinopathy Swelling and leakage of retinal vascular supply (red spots) If caught early, can be repaired. If not, will cause blindness vitreous floaters Chunks of vitreous break off- usually harmless unless accompanies by lateral flashes of light (possible retinal detachment)

Chapter 7: The Sensory Systems Lesson 7.2 The Ear

The Ear anatomy of the ear functions of the ear Outer, middle and inner functions of the ear Hearing and Equilibrium disorders and infections of the ear

Anatomy of the Ear- 1 of 3 External ear auricle (pinna) auditory canal External acoustic meatus 1” long, ¼” diameter tube Lined with ceruminous glands (earwax) Cleans, lubricates and protect the ear tympanic membrane Eardrum separates outer and middle ear Sound waves cause it to vibrate

Anatomy of the Ear (2 of 3) Middle ear (tympanic cavity) Open chamber in the temporal lobe of the skull T. membrane is on the lateral side Medial side is membrane covered oval window ( superior) and round window ( inferior) Ossicles (3 smallest bones in the body) connect the t. membrane and oval window: Transmit and amplify sound waves Malleus (hammer) attaches to t membrane incus (anvil) attaches to malleus stapes (stirrup) attaches to incus and oval window Eustachian tube connects middle ear to pharynx Equalizes pressure (chewing gum or yawning in a plane)

Anatomy of the Ear 3 of 3 Internal ear- Balance semicircular canals Bony labyrinth Parilymph- clear Membranous labyrinth contained within Endolymph- thicker Vestibule Central portion Transmits balance information Cochlea Shell Nerve transmits information about hearing Vestibular and cochlear nerves join to form the vestibulocochlear (the name of a cranial) nerve

Anatomy of the Ear

Functions of the Ear Hearing Vibrations of the t. membrane move the ossicles, which move the oval window and the fluids of the inner ear Cochlea allows hearing cochlear duct is central, membranous labyrinth of cochlea Spiral organ of Corti contains hair cells (hearing receptors) Stimulated by endolymph moving tectorial membrane Short hair cells =higher pitches Longer hair cells =lower pitches (more flexible) Hair cells stimulate cochlear nerve Nerve sends signals to temporal lobe of brain

Functions of the Ear Equilibrium Balance Vestibule Comes from the inner ear Vestibule semicircular canals (3) Contain hair cells Stimulated by endolymph movement Vestibular hair cells stimulate the vestibular nerve and transmit to the cerebellum for both static (in one place) or dynamic ( moving) equilibrium

Disorders and Infections of the Ear Deafness: any loss of hearing Can be caused by injury to the inner or middle ear, loud noises regularly, damage to the hair cells, earwax, scarring of the t. membrane, damage to auditory nerves or brain. Presbycusis- age related hearing loss Hearing aids amplify all sounds or boost certain frequencies In canal- inside ear canal (mild to moderate) Half shell- in the outer pinna (mild to moderately severe) Behind the ear- most types of loss

Disorders and Infections of the Ear Tinnitus: ringing in the ear Damaged hair cells= random movement Loud music or noise exposure ( more common in recent years….. Headphones?) external otitis (swimmer’s ear) Bacterial or fungal infection of auditory canal Pain, fever, temporary hearing loss Prevention- clean and dry ear canal after submersion in water

Disorders and Infections of the Ear otitis media (middle ear infection) Bacterial or viral, usually URI Common in babies and toddlers (lack of eustachian development) Pain, swelling, pus Antibiotics if bacterial “ tubes” in t. membrane to equalize pressure labyrinthitis (inner ear infection) Swelling in semicircular canals (Antibiotics if bacterial) Vertigo (severe dizziness), nausea and vomiting Chronic inflammation=Meniere’s disease Perioidic, severe vertigo and progressive hearing loss

Chapter 7: The Sensory Systems Lesson 7.3 Smell and Taste

Smell and Taste olfactory sense (sense of smell) injuries and disease of the nose gustatory sense (sense of taste) disorders of the tongue

Olfactory Sense olfactory region- dime sized on top of nasal cavity olfactory receptor cells- neurons responsible for smell olfactory hairs extend from ORC into nasal cavity Covered with mucous Odor molecules erode mucous and stimulate hairs Very few molecules required to send impulse- smell acclimation olfactory nerve made of olfactory filaments. Send impulses to olfactory bulb to olfactory cortex of brain Passes through the limbic system Smells tied to memory

Olfactory Sense

Injuries and Disorders of the Nose rhinitis inflammation of nasal mucous membranes Common cold, allergies, drugs Irritation releases histamines to produce drainage and congestion Taking antihistamines blocks release of histamines and prevents action septum problems (septum divides L and R nares) deviated septum usually due to injury. Surgical repair Perforated septum- holes in septum (drugs, injury, toxic fumes). Surgical repair

Gustatory Sense taste buds (>10,000) All over the inner mouth Most as Papillae: T.B. on tongue gustatory cells on papilla send up gustatory hairs through taste pores (openings in taste buds) Tastants : chemicals from dissolved food in saliva Stimulate gustatory hairs to send impulses to brain Through the facial nerve, glossopharyngeal and vagus nerve 5 basic tastes: sweet, salty, sour, bitter, umami Umami- beef/ MSG One g. cell= 1 taste, but each papilla contains 50-100 cells, so all 5 are covered

Gustatory Sense 70-90% of taste is influenced by smell. Smell allows us to distinguish tastes Over 10, 000 flavors Flavor is Taste Smell Texture Consistency Temperature

Disorders of the Tongue Infection/ Injury severely bitten tongue during a traumatic accident tongue piercing Both require antibiotics Fastest healing part of body. Why? abnormal growth on tongue hairy tongue (abnormal growth of gustatory hairs) Poor hygiene, tobacco, medications, radiation Good hygiene prevents AND cures burning mouth syndrome Many causes, including damage to receptors, dry mouth, nutritional deficiencies, infection, hormones Treatment based on symptoms and causes