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1 How to Use this program: Read this Lesson Answer ALL TEST questions. Check your answers Be sure to sign and date the test sheet. Take as much time as you need.

2 Lesson 12 The Sensory System In this chapter... you will learn about: The sensory system. Some common problems of the sensory system. 2

3 Definitions Bifocal: Two different prescriptions in one eyeglass lens. Cataract: Clouding of the lens of the eye. Environment: The world around you. Glaucoma: Increased pressure in the eye, due to the inability of the fluid in the eye (vitreous humor) to circulate properly. Myopia: Difficulty seeing things that are far away. Peripheral Vision: Vision seen to the side while looking straight ahead. Presbyopia: Decrease in the ability of the eye to focus. 3

4 Definitions continued.. Presbycusis: Hearing loss for high-pitched sounds. Senses: Sight, hearing, smell, taste, and touch. Sensory System: Eyes, ears, nose, tongue, and skin. Stimulus: Action that causes a response. Tinnitus: Constant ringing in the ear. 4

5 All the information we receive from the world around us comes to us through organs that are responsible for our five senses. These organs and senses are. 1. Eyes: Sight 2. Ears: Hearing 3. Nose: Smell 4. Tongue: Taste 5. Skin: Touch The sensory system is made up of these five organs that bring information to our brains about changes in the world around us. Any change in our environment is called a stimulus. 5

6 The sense organ reacts to a stimulus by sending a message about the change to the brain. This information can be used by the brain to start a response to the change. For example, if you step into a warm room, your skin picks up the stimulus of the heat. The information that the room is very warm travels from your skin to your brain. The brain then sends a message that may result in your removing your sweater. If any one of these sense organs is impaired, some of the input from your environment will be missing. 6

7 SIGHT The Sensory System The eye is the organ of sight. It works like a camera, giving the brain a picture of the environment. The parts of the eye are: 1. Sclera. The white :part of the eyeball. 2. Iris. The circle of color in the center of the eye (blue, brown, green, violet, hazel). 3. Pupil. The dark opening in the center of the iris where light enters. 7

8 SIGHT continued. 4. Cornea. Clear circular area of the eyeball, called the window of the eye. 5. Aqueous Humor. Fluid produced by the eye which fills the space between the cornea and the lens. 6. Vitreous Humor. Clear liquid which fills the eyeball. 7. Lens. Lies directly behind the pupil and focuses the picture of what you see on the retina. 8. Retina. Back part of the eye which receives the picture and sends nerve impulses to the optic nerve. 9. Optic Nerve. Receives the nerve impulse from the retina and sends it to the brain so the brain can interpret what you see. 8

9 SIGHT continued. Age-Related Changes in Vision The most common change in the eye as the person ages is a condition called presbyopia. The lens loses some of its elasticity and ability to focus rapidly and clearly, particularly, on an object close to the eye. The person must hold small print farther and farther away in order to read it. Reading glasses which slightly magnify the print are the usual way of correcting presbyopia. With age there is also a loss of peripheral vision, or side visit Myopia is difficulty seeing things that are far from the eye If the person has myopia and begins to develop presbyopia as well, bifocals are usually the answer. 9

10 SIGHT continued. Diseases of -the Eye There are two diseases of the eye often found in the older client: cataracts and glaucoma.. Cataracts. When a cataract occurs, the eye lens becomes cloudy. Since the lens is no longer transparent, vision is impaired. As the lens becomes yellow and cloudy, the perception of color change This change affects colors in the blue-green range. The ability to tolerate glare. and bright light is also, decreased. Eventually, blindness will result. Fortunately, surgery to remove the clouded lens is now a relatively safe and simple procedure. 10

11 SIGHT continued. Diseases of -the Eye Glaucoma. This is a much more serious disease of the eye. Pressure from accumulated fluid builds in the eye and can damage the optic nerve. The person who is developing glaucoma may complain of pain in the eye or see halos around lights. There may also be a loss of peripheral and central, or front, vision. If detected early, glaucoma can be treated to prevent damage to the optic nerve. The test for glaucoma is simple and painless, and it should be a routine part of any eye examination persons past middle age. If untreated, glaucoma results in permanent blindness. Treatments in medication and surgery. 11

12 HEARING The Sensory System Hearing is the function of the ear. The ear is also involved in the sense of balance. Sounds enter the ear and are transmitted to the brain. There are 4 main parts to the ear: 1.Outer Ear. This is the body part which we can see. 2.Eardrum. The membrane which separates the outer ear from the middle ear. 3.Middle Ear. This contains three tiny bones which are set into vibration by the eardrum. These bones are the hammer, anvil, and stirrup. 12

13 HEARING continued 4. Inner Ear. This contains two parts. One is the cochlea, a snail shell-shaped tube, which contains the fluid necessary for us to maintain our sense of balance. The other part of the inner ear contains tiny hair like nerve cells which receive the signals from the middle ear and transfer them to the brain. 13

14 HEARING continued Age-Related Changes in Hearing Most older people will have some hearing loss. The most common hearing deficit in aging is called Presbycusis. This results in a reduction in the ability to hear higher-pitched sounds. The person with Presbycusis may hear the sound of a conversation, but be unable to understand some of the words, especially with speakers who have high-pitched voices. Increasing the volume of speech often helps the person hear more clearly. 14

15 HEARING continued Age-Related Changes in Hearing continued.. Another hearing problem among the older clients is tinnitus, a continual ringing, roaring, or hissing sound in the ears. It is not known what causes tinnitus or how to correct it. This can be very frustrating, and the only remedy is to learn to ignore the noise. Severe loss of hearing may seriously interfere with a client's ability to interact and communicate with others. 15

16 HEARING continued Age-Related Changes in Hearing continued.. Hearing aids amplify all sounds but do not correct or cure the hearing problem. Hearing aids help the client hear better. This is because the hearing aid makes the sounds louder, though it does not make them clearer. Hearing aids are expensive and must be handled carefully and cared for properly by the home health aide. If a client reports a sudden change in hearing, don't forget to check the batteries in any hearing aid the client uses. 16

17 SMELL The Sensory System The special lining of the upper part of the nose enables us to smell and detect differences in odors. This sense is the least understood, and it is not known how this information is transmitted to the brain. Age-Related Changes in Smell The sense of smell declines with age. Many older people have difficulty identifying common odors. Since the sense of smell is important to taste, this can contribute to a loss of appetite. 17

18 TASTE The Sensory System The tongue is the organ for the sense of taste. Tiny taste buds on the tongue allow us to tell the difference among sweet, sour, bitter, and salty tastes. The taste buds for sweet and salty are located near the tip of the tongue. The buds for sour are in the middle, and those for bitter are located at the base of the tongue. In more complicated tastes, the brain combines these four tongue sensations, plus information from the sense of smell. 18

19 TASTE The Sensory System Age-Related Changes in Taste The number of taste buds decrease as a person ages. The tastes for sweet and salty seem to decline first, causing the older person to increase the use of sugar and salt. The loss of taste often causes a loss of appetite. 19

20 TOUCH The Sensory System The skin is the organ for the sense of touch. Special sensory nerve cells send different messages about touch to the brain. These nerve cells can identify pressure, pain, heat, and cold. Age-Related Changes in Touch The special nerve cells lose some of their sensitivity as a person ages. The older person may not experience normal levels of pain or accurately perceive hot and cold. 20

21 TOUCH continued. Diseases Affecting the Sense of Touch continued There are some diseases which can affect the older person's sense of touch. Rheumatoid arthritis causes deformities in the hands, making it difficult and painful for the person to handle and touch things. The tremors of Parkinson's disease may cause the person to avoid touching things for fear of dropping or damaging them. Clients with diabetes mellitus may not be able to sense hot or cold while bathing and special care should be taken to make sure they don't burn themselves. 21

22 SENSORY INPUT We all require varied sensory input to function normally. Age and disease affect all five of the senses. This results in less information being sent to the brain about the environment. If the loss is severe, the person can become confused and angry, as well as have difficulty with the activities of daily living. 22

23 Complete the test and turn in for credit Answer ALL TEST questions. Check your answers Be sure to sign and date the test sheet. This completes the lesson for this month. Information for this lesson was taken from MEDCOM TRAINEX publications