2 Objectives (cont.) 33-1Spell, define, and correctly use the Key Terms in this chapter. 33-2Describe the anatomy of the nose and the function of each part. 33-3Describe how smell sensations are created and interpreted. 33-4Describe the anatomy of the tongue and the function of each part. The Special Senses System
3 33-5Describe how taste sensations are created and interpreted. 33-6Name the four primary taste sensations. 33-7Describe the anatomy of the eye and the function of each part. 33-8Describe various disorders of the eye. 33-9Trace the path of a visual image through the eye and to the brain for interpretation Objectives (cont.) The Special Senses System
Describe the anatomy of the ear and the function of each part Describe various disorders of the ear Explain how sounds travel through the ear and are interpreted in the brain Explain the role of the ear in equilibrium. Objectives (cont.) The Special Senses System
5 Introduction Special senses that have sensory receptors located within relatively large, sensory organs in the head; Nose – smell Tongue – taste Eyes – vision Ears – hearing and equilibrium
6 Nose Smell receptors Olfactory receptors Chemoreceptors Respond to changes in chemical concentrations Chemicals must be dissolved in the mucus of the nose to activate smell receptors
7 Smell Sensation send the information along olfactory bulbs and tracts different areas of the cerebrum cerebrum interprets the information as a particular type of smell Smell receptors are activated, they send their information to the olfactory nerves
8 Smell undergoes sensory adaptation Same chemical can only stimulate smell receptors for a limited amount of time Smell receptors no longer respond to the chemical and you can no longer smell You smell perfume when you first encounter it but in a few minutes, you no longer smell it. Smell undergoes sensory adaptation Same chemical can only stimulate smell receptors for a limited amount of time Smell receptors no longer respond to the chemical and you can no longer smell You smell perfume when you first encounter it but in a few minutes, you no longer smell it. Smell Sensation (cont.)
9 Apply Your Knowledge You notice an odor coming from a patient when you enter the exam room. Why would the patient not be able to smell it?
10 Answer Apply Your Knowledge - Answer After a few minutes, smell receptors no longer respond to the chemical and the patient can no longer smell the odor. You notice an odor coming from a patient when you enter the exam room. Why would the patient not be able to smell it?
11 Tongue Taste or gustatory receptors –taste buds Found on "the bumps" of the tongue (papillae) Taste buds are microscopic Also on roof of your mouth and walls of your throat Taste or gustatory receptors –taste buds Found on "the bumps" of the tongue (papillae) Taste buds are microscopic Also on roof of your mouth and walls of your throat Click for Larger View
12 Tongue (cont.)
13 Taste Sensation Four types of taste cells - activated by a particular group of chemicals Sweet - tip of the tongue. Sour - sides of the tongue. Salty - tip and sides of the tongue. Bitter - back of the tongue Four types of taste cells - activated by a particular group of chemicals Sweet - tip of the tongue. Sour - sides of the tongue. Salty - tip and sides of the tongue. Bitter - back of the tongue
15 Outer layer: Sclera is the “white of the eye” and does not allow light to enter the eye Cornea - anterior to the sclera Allows light to enter the eye (“window of the eye”) Contains sensory receptors can detect even the smallest of particles Eye (cont.)
16 Middle layer: Also called vascular and pigmented layer Richly supplied with blood vessels and pigments Choroid lines the sclera and absorb extra light Ciliary body functions to hold and move the lens to focus the eye. Cloudy areas on the lens are called “cataracts.” Hole in iris is called the pupil. Eye (cont.)
17 Inner layer: Also called the retina Richly supplied with blood vessels and pigments Contains visual receptors called rods and cones Rods allow us to detect black, white, and gray shades and images in dim light. Cones allow us to see images in bright light Cones allow us to see color. Eye (cont.)
18 Eyelid Eyelid - skin, muscle, and dense connective tissue. Orbicularis oculi Orbicularis oculi muscle and is responsible for blinking Conjunctivas Conjunctivas - mucous membranes Line the inner surfaces of the eyelids Fold back onto the anterior surface of each eyeball Eye (cont.)
19 Vitreous humor Lens Choroid Sclera Retina Pupil Iris Cornea Conjunctiva Eye (cont.) Draw a line to each part of the eye.
20 Lacrimal apparatus consists of lacrimal glands and nasolacrimal ducts. Mostly water but also contain enzymes that can destroy bacteria and viruses Lacrimal apparatus consists of lacrimal glands and nasolacrimal ducts. Mostly water but also contain enzymes that can destroy bacteria and viruses Lacrimal glands are on the lateral edge of each eyeball and they produce tears. Outer oily layer that prevents them from evaporating Lacrimal glands are on the lateral edge of each eyeball and they produce tears. Outer oily layer that prevents them from evaporating When a person cries, the abundance of tears entering the nose produces the “runny nose” associated with crying. Tears
21 Extrinsic eye muscles are skeletal muscles that move the eyeball Each eyeball has 6 extrinsic eye muscles attached to them that move the eyeball Superiorly Inferiorly Laterally Medially Eye Muscles
22 Eye works like a camera light passes through the cornea, pupil, lens and fluids of the eye, which focuses the light onto the retina The image is projected upside down on the retina Retina converts the light into nerve impulses that are sent to the brain The brain interprets these impulses, turns the image right- side up and develop a picture of the object. Process of Seeing
23 Parts of the Eye ChoroidAbsorbs extra light in eye Ciliary BodyHolds lens, moves lens for focusing IrisControls amount of light entering eye LensFocuses light onto retina
24 RetinaContains visual receptors RodsAllow vision in dim light, detect black-and-white images, detect broad outlines of images ConesAllow vision in bright light, detect colors, detect details Optic NerveCarries visual information from rods and cones toward the brain Parts of the Eye (cont.)
25 Aqueous Humor - nourishes structures in anterior eye cavity Vitreous Humor - holds retina in place; maintains shape of eyeball Parts of the Eye (cont.)
26 Common eye problems Conjunctivitis - inflammation of the conjunctiva Blepharitis - inflammation of the eyelid Corneal abrasions - scratching of the cornea Eye Disorders (cont.)
27 Astigmatism Astigmatism - cornea has an abnormal shape which causes blurred images during distant or near vision. Amblyopia Amblyopia - commonly called “lazy eye” Cataracts Cataracts - structures in the lens that prevent light from going through the lens Dry Eye Syndrome Dry Eye Syndrome - one of the most common eye problems treated by physicians Glaucoma Glaucoma - condition in which too much pressure is created in the eye by excessive aqueous humor Eye Disorders (cont.)
28 Hyperopia Hyperopia - called farsightedness Myopia Myopia - called nearsightedness Presbyopia Presbyopia - a common eye disorder that develops with age - difficulty seeing objects close up Eye Disorders (cont.)
29 Macular Degeneration Macular Degeneration - a progressive disease that usually affects people over 50. It occurs when the retina no longer receives an adequate blood supply. Retinal Detachment Retinal Detachment - occurs when the layers of the retina separate. Considered a medical emergency and if not treated right away, leads to permanent vision loss. Eye Disorders (cont.)
30 Eye Safety and Protection Works Common eye injuries that occur while playing a sport include: Scratched corneas Inflamed iris Bleeding in the anterior eye chamber Traumatic cataracts Inflamed retinas Eye socket fractures
32 The Ear (cont.) Auricle Tympanic membrane Ear canal Eustachian tube Auditory nerve Cochlea Semicircular canals Draw a line to each part of the ear.
33 Hearing Process Sound enters the external ear which makes the eardrum vibrate The middle ear amplifies the vibrations and the waves cause the tiny hairs in the cochlea to bend. Movement of the hairs triggers nerve impulses. The impulses are transmitted via auditory nerve to the brain. The brain perceives the sound.
34 Ear and Balance Brain constantly monitors the position of one’s body on the information received from the semicircular canals, eyes and muscles. Change in position is detected by the canal and passed to the brain The brain uses this information to maintain balance
35 Disorders of the Ear Conductive deafness Conductive deafness -produced when sound waves cannot be conducted through the ear Sensorineural deafness Sensorineural deafness - produced when neural structures associated with the ear are damaged Tinnitus Tinnitus - ringing in the ear
36 Apply Your Knowledge What would happen if a patient had damage to the middle ear?
37 Answer Apply Your Knowledge - Answer The middle ear amplifies the vibrations and the waves cause the tiny hairs in the cochlea to bend so if there was damage to this part of the ear, the patient may have impaired hearing. What would happen if a patient had damage to the middle ear?
38 How to Recognize Hearing Problems in Children Hearing problems in babies and toddlers are not easy to recognize By 4 months the infant should: Startle by loud noises (barking dog, hand- clap, etc.) Wake up at the sound of voices. Turn head or move eyes to follow a sound Recognize the mother’s voice better than other voices
39 Summary Medical Assistant Knowledge of the Special Senses will assist you in providing care for the patient with diseases and disorders of the special senses.