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15-1 Anatomy and Physiology, Sixth Edition Rod R. Seeley Idaho State University Trent D. Stephens Idaho State University Philip Tate Phoenix College Copyright.

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Presentation on theme: "15-1 Anatomy and Physiology, Sixth Edition Rod R. Seeley Idaho State University Trent D. Stephens Idaho State University Philip Tate Phoenix College Copyright."— Presentation transcript:

1 15-1 Anatomy and Physiology, Sixth Edition Rod R. Seeley Idaho State University Trent D. Stephens Idaho State University Philip Tate Phoenix College Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. *See PowerPoint Image Slides for all figures and tables pre-inserted into PowerPoint without notes. Chapter 15 Lecture Outline *

2 15-2 Chapter 15 The Special Senses

3 15-3 Special Senses Olfaction Taste Visual system Hearing and balance

4 15-4 Olfaction Sense of smell –Olfactory neurons in this epithelium Bipolar neurons –Olfactory hairs Cilia which lies in mucous Odors –Odorants bind to chemoreceptor molecules –Depolarize and initiate action potentials in neurons –Low threshold for odor detection

5 15-5 Neuronal Pathways of Olfaction

6 15-6 Taste Detected by taste buds Papillae –Vallate –Fungiform –Foliate –Filiform Histology –Support cells –Gustatory cells Hairs Function –Receptors on hairs detect dissolved substances Taste types –Sour –Salty –Bitter –Sweet –Umami

7 15-7 Papillae and Taste Buds

8 15-8 Actions of Major Tastants

9 15-9 Neuronal Pathways for Taste

10 15-10 Visual System Eye Accessory structures –Eyebrows, eyelids, eyelashes, tear glands –Protect eyes from sunlight and damaging particles Optic nerve (II) –Tracts –Pathways Eyes respond to light and initiate afferent action potentials

11 15-11 Accessory Structures of Eye Eyebrows –Prevent running perspiration into eyes –Shade Eyelids or palpebrae –Consist of 5 tissue layers –Protect and lubricate Conjunctiva –Covers inner eyelid and anterior part of eye Lacrimal apparatus Extrinsic eye muscles

12 15-12 Lacrimal Apparatus Lacrimal apparatus –Lacrimal Gland: Produces tears to moisten, lubricate, wash Lacrimal Canaliculi –Collects excess tears Punctum Lacrimal Sac Nasolacrimal duct –Opens into nasal cavity

13 15-13 Extrinsic Eye Muscles

14 15-14 Anatomy of the Eye Three coats or tunics –Fibrous: Consists of sclera and cornea –Vascular: Consists of choroid, ciliary body, iris –Nervous: Consists of retina

15 15-15 Anatomy of the Eye Fibrous tunic: Outer –Sclera: White outer layer, maintains shape, protects internal structures, provides muscle attachment point, continuous with cornea –Cornea: Avascular, transparent, allows light to enter eye and bends and refracts light Vascular tunic: Middle –Iris: Controls light entering pupil; smooth muscle –Ciliary muscles: Control lens shape; smooth muscle Retina: Inner –Contains neurons sensitive to light –Macula lutea or fovea centralis: Area of greatest visual acuity –Optic disc: Blind spot Compartments –Anterior: Aqueous humor –Posterior: Vitreous humor Lens –Held by suspensory ligaments attached to ciliary muscles –Transparent, biconvex

16 15-16 Functions of the Complete Eye Eye functions like a camera Iris allows light into eye Lens, cornea, humors focus light onto retina Light striking retina is converted into action potentials relayed to brain

17 15-17 Light Visible light: Portion of electromagnetic spectrum detected by human eye Refraction: Bending of light –Divergence: Light striking a concave surface –Convergence: Light striking a convex surface Focal point: Point where light rays converge and cross

18 15-18 Focus and Accommodation Emmetropia: Normal resting condition of lens Far vision: 20 feet or more from eye Near vision: Closer than 20 feet –Accommodation –Pupil constriction –Convergence

19 15-19 The Retina Provides black backdrop for increasing visual acuity Sensory retina and pigmented retina Photoreceptors –Rods: Noncolor vision Rhodopsin reduction: Light adaptation Rhodopsin production: Dark adaptation –Cones: Color vision

20 15-20 Sensory Receptor Cells

21 15-21 Rhodopsin Cycle

22 15-22 Rod Cell Hyperpolarization

23 15-23 Visual Pathways

24 15-24 Eye Disorders Myopia: Nearsightedness –Focal point too near lens, image focused in front of retina Hyperopia: Farsightedness –Image focused behind retina Presbyopia –Degeneration of accommodation, corrected by reading glasses Astigmatism: Cornea or lens not uniformly curved Strabismus: Lack of parallelism of light paths through eyes Retinal detachment –Can result in complete blindness Glaucoma –Increased intraocular pressure by aqueous humor buildup Cataract –Clouding of lens Macular degeneration –Common in older people, loss in acute vision Diabetes –Dysfunction of peripheral circulation

25 15-25 The Ear External ear: Hearing; terminates at eardrum Middle ear: Hearing; contains auditory ossicles Inner ear: Hearing and balance; interconnecting fluid-filled tunnels and chambers

26 15-26 The Ear External ear –Auricle or pinna: elastic cartilage –External auditory meatus Lined with hairs and ceruminous glands –Tympanic membrane Vibrated by sound waves Middle ear –Auditory or eustachian tube Opens into pharynx, equalizes pressure Ossicles: malleus, incus, stapes: transmit vibrations Oval window

27 15-27 Inner Ear Labyrinth –Bony Cochlea: Hearing Vestibule: Balance Semicircular canals: Balance –Membranous -Lymphs –Endolymph In membranous labyrinth –Perilymph Space between membranous and bony labyrinth

28 15-28 Structure of Cochlea

29 15-29 Auditory Function Vibrations produce sound waves –Volume or loudness : Function of wave amplitude –Pitch: Function of wave frequency –Timbre: Resonance quality or overtones of sound

30 15-30 Effect of Sound Waves on Cochlear Structures

31 15-31 CNS Pathways for Hearing

32 15-32 Balance Static –Evaluates position of head relative to gravity –Detects linear acceleration and deceleration –Utricle and saccule Maculae: Consist of hairs embedded in gelatinous mass containing otoliths Kinetic –Evaluates movements of head –3 semicircular canals Ampulla –Crista ampullaris –Cupula: endolymph moves when head moves

33 15-33 Structure of the Macula

34 15-34 Vestibule in Maintaining Balance

35 15-35 Semicircular Canals

36 15-36 CNS Pathways for Balance

37 15-37 Ear Disorders Tinnitus –Ringing, clicking, whistling in ear due to disorders in middle or inner ear Motion sickness –Dysfunctions caused by stimulation of semicircular canals during motion Otitis Media –Infections in the middle ear Earache –Results from otitis media, dental abscesses, TMJ pain

38 15-38 Effects of Aging on the Special Senses Slight loss in ability to detect odors Decreased sense of taste Lenses of eyes lose flexibility Development of cataracts, macular degeneration, glaucoma, diabetic retinopathy Decline in visual acuity and color perception


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