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Lesson 7.1: The Eye Lesson 7.2: The Ear Lesson 7.3: Smell and Taste

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) External- eyebrows, eyelashes, etc internal vision

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Lesson 7.1: The Eye Lesson 7.2: The Ear Lesson 7.3: Smell and Taste

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

  2. Chapter 7: The Sensory Systems Lesson 7.1 The Eye

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

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

  5. Extrinsic Muscles

  6. 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

  7. 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

  8. Internal Structures of the Eye

  9. Vision • retina • impulse • optic nerve • brain • optic chiasma • optic tracts • occipital lobe

  10. Vision Disorders

  11. Eye Diseases • conjunctivitis • 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

  12. Eye Diseases • macular degeneration • 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)

  13. Chapter 7: The Sensory Systems Lesson 7.2 The Ear

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

  15. 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

  16. 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)

  17. 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

  18. Anatomy of the Ear

  19. 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 endolymphmoving 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

  20. Functions of the Ear • Equilibrium • Balance • 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

  21. 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

  22. 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

  23. 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

  24. Chapter 7: The Sensory Systems Lesson 7.3 Smell and Taste

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

  26. 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

  27. Olfactory Sense

  28. 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

  29. 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 throughtaste 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

  30. 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

  31. 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

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