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Aging changes in the senses

As you age, the way your senses (hearing, vision, taste, smell, touch) give you information about the world changes. Your senses become less sharp, and this can make it harder for you to notice details.

Sensory changes can affect your lifestyle. You may have problems communicating, enjoying activities, and staying involved with people. Sensory changes can lead to isolation.

Your senses receive information from your environment. This information can be in the form of sound, light, smells, tastes, and touch. Sensory information is converted into nerve signals that are carried to the brain. There, the signals are turned into meaningful sensations.

A certain amount of stimulation is required before you become aware of a sensation. This minimum level of sensation is called the threshold. Aging raises this threshold. You need more stimulation to be aware of the sensation.

Aging can affect all of the senses, but usually hearing and vision are most affected. Devices such as glasses and hearing aids, or lifestyle changes can improve your ability to hear and see.

HEARING

Your ears have two jobs. One is hearing and the other is maintaining balance. Hearing occurs after sound vibrations cross the eardrum to the inner ear. The vibrations are changed into nerve signals in the inner ear and are carried to the brain by the auditory nerve.

Hearing and the cochlea - Animation

Sound waves entering the ear travel through the external auditory canal before striking the eardrum and causing it to vibrate. The eardrum is connected to the malleus, one of three small bones of the middle ear. Also called the hammer, it transmits sound vibrations to the incus, which passes them to the stapes. The stapes pushes in and out against a structure called the oval window. This action is passed onto the cochlea, a fluid-filled snail-like structure that contains the organ of Corti, the organ for hearing. It consists of tiny hair cells that line the cochlea. These cells translate vibrations into electrical impulses that are carried to the brain by sensory nerves. In this cut-view, you can see the organ of Corti with its four rows of hair cells. There is an inner row on the left and three outer rows on the right. Let's watch this process in action. First, the stapes rocks against the oval window. This transmits waves of sound through the cochlear fluid, sending the organ of Corti into motion. Fibers near the upper end of the cochlea resonate to lower frequency sound. Those near the oval window respond to higher frequencies.

Balance (equilibrium) is controlled in the inner ear. Fluid and small hair in the inner ear stimulate the auditory nerve. This helps the brain maintain balance.

As you age, structures inside the ear start to change and their functions decline. Your ability to pick up sounds decreases. You may also have problems maintaining your balance as you sit, stand, and walk.

Age-related hearing loss is called presbycusis. It affects both ears equally. Hearing, particularly the ability to hear high-frequency sounds, may decline. You may also have trouble telling the difference between certain sounds. Or, you may have problems hearing a conversation when there is background noise. If you are having trouble hearing, discuss your symptoms with your health care provider. One way to manage hearing loss is by getting fitted with hearing aids.

Persistent, abnormal ear noise (tinnitus) is another common problem in older adults. Causes of tinnitus may include wax buildup, medicines that damage structures inside the ear or mild hearing loss. If you have tinnitus, ask your provider how to manage the condition.

Impacted ear wax can also cause trouble hearing and is common with age. Your provider can remove impacted ear wax.

VISION

Vision occurs when light is processed by your eye and interpreted by your brain. Light passes through the transparent eye surface (cornea). It continues through the pupil, the opening to the inside of the eye. The pupil becomes larger or smaller to control the amount of light that enters the eye. The colored part of the eye is called the iris. It is a muscle that controls pupil size. After light passes through your pupil, it reaches the lens. The lens focuses light on your retina (the back of the eye). The retina converts light energy into a nerve signal that the optic nerve carries to the brain, where it is interpreted.

Seeing - Animation

Vision is the dominant sense for most people with sight. The organ of sight is the eye. Think of it as a slightly irregular, hollow sphere that takes in light and translates it into images. If we enlarge the eye and look inside it, we can discover how that's done. Inside the eye are various structures working together to create an image the brain can understand. Among these are the cornea, a clear dome-like structure covering the iris or colored part of the eye, the lens directly below it, and the retina, which lines the back of the eye. The retina consist of thin layers of light-sensitive tissue. This candle can help us understand how the eye captures images and then sends them to the brain. First, the candlelight passes through the cornea. As it does, it's bent, or refracted, onto the lens. As the light passes through the lens, it's bent a second time. Finally, it arrives at the retina where an image is formed. This double bending, though, has reversed the image and turned it upside down. If that was the end of the story, the world would always appear upside down. Fortunately, the image is turned right side up in the brain. Before that can happen, the image needs to travel as impulses along the optic nerve and enter the brain's occipital lobe. When the image forms there, it regains its proper perspective. Now let's consider two common conditions that cause blurry vision. The eye's shape is important for keeping things in focus. With normal vision, light focuses precisely on the retina at a location called the focal point. But what happens if the eye is longer than normal? The longer the eye, the more distance there is between the lens and retina. But the cornea and lens still bend light the same way. That means the focal point will be somewhere in front of the retina rather than on it. This makes it difficult to see things that are far away. A person with a long eye is said to be nearsighted. Glasses with concave lenses can correct nearsightedness. The lens widens the plain of light coming through the cornea. That pushes the focal point back onto the retina. Farsightedness is just the opposite. The eye's length is too short. When that happens, the focal point is behind the retina. So it's difficult to see things that are up close. Glasses with convex lenses narrow the plain of light. Narrowing the light passing through the cornea moves the focal point back onto the retina and can correct farsightedness.

All of the eye structures change with aging. The cornea becomes less sensitive, so you might not notice eye injuries. By the time you turn 60, your pupils may decrease to about one third of the size they were when you were 20. The pupils may react more slowly in response to darkness or bright light. The lens becomes yellowed, less flexible, and slightly cloudy leading to the development of cataracts. The fat pads supporting the eyes decrease and the eyes sink into their sockets. The eye muscles become less able to fully rotate the eye.

As you age, the sharpness of your vision (visual acuity) gradually declines. The most common problem is difficulty focusing the eyes on close-up objects. This condition is called presbyopia. Reading glasses, bifocal glasses, or contact lenses can help correct presbyopia.

You may be less able to tolerate glare. For example, glare from a shiny floor in a sunlit room can make it difficult to get around indoors. You may have trouble adapting to darkness or bright light. Problems with glare, brightness, and darkness may cause problems driving at night.

As you age, it gets harder to tell blues from greens than it is to tell reds from yellows. Using warm contrasting colors (yellow, orange, and red) in your home can improve your ability to see. Keeping a red light on in darkened rooms, such as the hallway or bathroom, makes it easier to see than using a regular night light.

With aging, the gel-like substance (vitreous) inside your eye starts to shrink. This can create small particles called floaters in your field of vision. In most cases, floaters do not reduce your vision. But if you develop floaters suddenly or have a rapid increase in the number of floaters, you should have your eyes checked by a professional, as this may indicate a retinal detachment.

Reduced peripheral vision (side vision) is common in older people. This can limit your activity and ability to interact with others. It may be hard to communicate with people sitting next to you because you cannot see them well. Driving can become dangerous.

Weakened eye muscles may prevent you from moving your eyes in all directions. It may be hard to look upward. The area in which objects can be seen (visual field) gets smaller.

Aging eyes also may not produce enough tears. This leads to dry eyes which may be uncomfortable. When dry eyes are not treated, infection, inflammation, and scarring of the cornea can occur. You can relieve dry eyes by using eye drops or artificial tears.

The upper eyelids may sag because of weakened muscular support. This may lead to visual loss if the sagging is severe.

Common eye disorders that cause vision changes that are NOT normal include:

  • Cataracts -- clouding of the lens of the eye
  • Glaucoma -- rise in fluid pressure in the eye
  • Macular degeneration -- disease in the macula (responsible for central vision) that causes vision loss
  • Retinopathy -- disease in the retina often caused by diabetes or high blood pressure

If you are having vision problems, discuss your symptoms with your provider.

TASTE AND SMELL

The senses of taste and smell work together. Most tastes are linked with odors. The sense of smell begins at the nerve endings high in the lining of the nose.

Smelling - Animation

As a person inhales, air and scent molecules move past the smell receptors in the nose. In turn, the smell receptors relay a signal to the brain. Smells can trigger memories and emotional responses.

You have about 10,000 taste buds. Your taste buds sense sweet, salty, sour, bitter, and umami flavors. Umami is a taste linked with foods that contain glutamate, such as the seasoning monosodium glutamate (MSG).

Tasting - Animation

The tongue has about 10,000 taste buds. The taste buds are linked to the brain by nerve fibers. Food particles are detected by the taste buds, which send nerve signals to the brain. Certain areas of the tongue are more sensitive to certain tastes, like bitter at the back of the tongue, sour along either side toward the back, sweet on the front surface, or salty around the front edge. Often, taste sensations are a mixture of these qualities.

Smell and taste play a role in food enjoyment and safety. A delicious meal or pleasant aroma can improve social interaction and enjoyment of life. Smell and taste also allow you to detect danger, such as spoiled food, gases, and smoke.

The number of taste buds decreases as you age. Each remaining taste bud also begins to shrink. Sensitivity to the five tastes often declines after age 60. In addition, your mouth produces less saliva as you age. This can cause dry mouth, which can affect your sense of taste.

Your sense of smell can also diminish, especially after age 70. This may be related to a loss of nerve endings and less mucus production in the nose. Mucus helps odors stay in the nose long enough to be detected by the nerve endings. It also helps clear odors from the nerve endings.

Certain things can speed up the loss of taste and smell. These include diseases, smoking, and exposure to harmful particles in the air.

Decreased taste and smell can lessen your interest and enjoyment in eating. You may not be able to sense certain dangers if you cannot smell odors such as natural gas or smoke from a fire.

If your senses of taste and smell have diminished, talk to your provider. The following may help:

  • Switch to a different medicine, if the medicine you take is affecting your ability to smell and taste.
  • Use different spices or change the way you prepare food.
  • Buy safety products, such as a gas detector that sounds an alarm you can hear.

TOUCH, VIBRATION, AND PAIN

The sense of touch makes you aware of pain, temperature, pressure, vibration, and body position. Skin, muscles, tendons, joints, and internal organs have nerve endings (receptors) that detect these sensations. Some receptors give the brain information about the position and condition of internal organs. Though you may not be aware of this information, it helps to identify changes (for example, the pain of appendicitis).

Your brain interprets the type and amount of touch sensation. It also interprets the sensation as pleasant (such as being comfortably warm), unpleasant (such as being very hot), or neutral (such as being aware that you are touching something).

Feeling pain - Animation

Ouch!!! Gotcha! Pain, although often uncomfortable, is a protective mechanism that alerts us to potential or actual harm to the body's tissues. Here, the peripheral nervous system sent a pain message to the brain that a bee sting occurred on the nose. Let's take a look at an instant replay to see how this communication works. The pain receptors in the skin detect tissue damage from the bee sting. Then, the peripheral nerves send a pain signal to the brain. The Brain analyzes the pain signal. Ouch!!! In turn, the brain delivers a message back to the muscles of the arm to react. Hasta la beesta, babee! As you can tell, it's a very effective system.

With aging, sensations may be reduced or changed. These changes can occur because of decreased blood flow to the nerve endings or to the spinal cord or brain. The spinal cord transmits nerve signals and the brain interprets these signals.

Health problems, such as a lack of certain nutrients, can also cause sensation changes. Brain surgery, problems in the brain, confusion, and nerve damage from injury or long-term (chronic) diseases such as diabetes can also result in sensation changes.

Symptoms of changed sensation vary based on the cause. With decreased temperature sensitivity, it can be hard to tell the difference between cool and cold and hot and warm. This can increase the risk of injury from frostbite, hypothermia (dangerously low body temperature), and burns.

Reduced ability to detect vibration, touch, and pressure increases the risk of injuries, including pressure ulcers (skin sores that develop when pressure cuts off blood supply to the area). After age 50, many people have reduced sensitivity to pain. Or, you may feel and recognize pain, but it does not bother you. For example, when you are injured, you may not know how severe the injury is because the pain does not trouble you.

You may develop problems walking because of reduced ability to perceive where your body is in relation to the floor. This increases your risk of falling, a common problem for older people.

Older people can become more sensitive to light touches because their skin is thinner.

If you have noticed changes in touch, pain, or problems standing or walking, talk with your provider. There may be ways to manage the symptoms.

The following measures can help you stay safe:

  • Lower the water heater temperature to no higher than 120°F (49°C) to avoid burns.
  • Check the thermometer to decide how to dress, rather than waiting until you feel overheated or chilled.
  • Inspect your skin, especially your feet, for injuries. If you find an injury, treat it. Do not assume the injury is not serious because the area is not painful.

OTHER CHANGES

As you grow older, you will have other changes, including:

Review Date: 7/21/2022

Reviewed By

Frank D. Brodkey, MD, FCCM, Associate Professor, Section of Pulmonary and Critical Care Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

References

Emmett SD. Otolaryngology in the elderly. In: Flint PW, Francis HW, Haughey BH, et al, eds. Cummings Otolaryngology: Head and Neck Surgery. 7th ed. Philadelphia, PA: Elsevier; 2021:chap 13.

Studenski S, Van Swearingen J. Falls. In: Fillit HM, Rockwood K, Young J, eds. Brocklehurst's Textbook of Geriatric Medicine and Gerontology. 8th ed. Philadelphia, PA: Elsevier; 2017:chap 103.

Walston JD. Common clinical sequelae of aging. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 22.

Disclaimer

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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Feeling pain - Animation

Ouch!!! Gotcha!

Pain, although often uncomfortable, is a protective mechanism that alerts us to potential or actual harm to the body's tissues.

Here, the peripheral nervous system sent a pain message to the brain that a bee sting occurred on the nose.

Let's take a look at an instant replay to see how this communication works.

The pain receptors in the skin detect tissue damage from the bee sting. Then, the peripheral nerves send a pain signal to the brain. The brain analyzes the pain signal.

Ouch!!!

In turn, the brain delivers a message back to the muscles of the arm to react.

Hasta la beesta, babee!

As you can tell, it's a very effective system.

 

Hearing and the cochlea - Animation

Sound waves entering the ear travel through the external auditory canal before striking the eardrum and causing it to vibrate.

The eardrum is connected to the malleus, one of three small bones of the middle ear. Also called the hammer, it transmits sound vibrations to the incus, which passes them to the stapes. The stapes pushes in and out against a structure called the oval window. This action is passed onto the cochlea, a fluid-filled snail-like structure that contains the organ of Corti, the organ for hearing. It consists of tiny hair cells that line the cochlea. These cells translate vibrations into electrical impulses that are carried to the brain by sensory nerves.

In this cut-view, you can see the organ of Corti with its four rows of hair cells. There is an inner row on the left and three outer rows on the right.

Let's watch this process in action.First, the stapes rocks against the oval window. This transmits waves of sound through the cochlear fluid, sending the organ of Corti into motion.

Fibers near the upper end of the cochlea resonate to lower frequency sound. Those near the oval window respond to higher frequencies.

 

Seeing - Animation

Vision is the dominant sense for most people with sight.

The organ of sight is the eye. Think of it as a slightly irregular, hollow sphere that takes in light and translates it into images.If we enlarge the eye and look inside it, we can discover how that's done.

Inside the eye are various structures working together to create an image the brain can understand. Among these are the cornea, a clear dome-like structure covering the iris or colored part of the eye, the lens directly below it, and the retina, which lines the back of the eye. The retina consists of thin layers of light-sensitive tissue.

This candle can help us understand how the eye captures images and then sends them to the brain.First, the candlelight passes through the cornea. As it does, it's bent, or refracted, onto the lens. As the light passes through the lens, it's bent a second time. Finally, it arrives at the retina where an image is formed.

This double bending, though, has reversed the image and turned it upside down. If that was the end of the story, the world would always appear upside down. Fortunately, the image is turned right side up in the brain.

Before that can happen, the image needs to travel as impulses along the optic nerve and enter the brain's occipital lobe. When the image forms there, it regains its proper perspective.

Now let's consider two common conditions that cause blurry vision. The eye's shape is important for keeping things in focus. With normal vision, light focuses precisely on the retina at a location called the focal point.

But what happens if the eye is longer than normal? The longer the eye, the more distance there is between the lens and retina. But the cornea and lens still bend light the same way. That means the focal point will be somewhere in front of the retina rather than on it.

This makes it difficult to see things that are far away. A person with a long eye is said to be nearsighted. Glasses with concave lenses can correct nearsightedness.

The lens widens the plain of light coming through the cornea. That pushes the focal point back onto the retina.

Farsightedness is just the opposite. The eye's length is too short. When that happens, the focal point is behind the retina. So it's difficult to see things that are up close.

Glasses with convex lenses narrow the plain of light. Narrowing the light passing through the cornea moves the focal point back onto the retina and can correct farsightedness.

 

Tasting - Animation

The tongue has about 10,000 taste buds. The taste buds are linked to the brain by nerve fibers. Food particles are detected by the taste buds, which send nerve signals to the brain.

Certain areas of the tongue are more sensitive to certain tastes, like bitter at the back of the tongue, sour along either side toward the back, sweet on the front surface, or salty around the front edge. Often, taste sensations are a mixture of these qualities.

 

Smelling - Animation

As a person inhales, air and scent molecules move past the smell receptors in the nose. In turn, the smell receptors relay a signal to the brain. Smells can trigger memories and emotional responses.

 

Feeling pain - Animation

Ouch!!! Gotcha!

Pain, although often uncomfortable, is a protective mechanism that alerts us to potential or actual harm to the body's tissues.

Here, the peripheral nervous system sent a pain message to the brain that a bee sting occurred on the nose.

Let's take a look at an instant replay to see how this communication works.

The pain receptors in the skin detect tissue damage from the bee sting. Then, the peripheral nerves send a pain signal to the brain. The brain analyzes the pain signal.

Ouch!!!

In turn, the brain delivers a message back to the muscles of the arm to react.

Hasta la beesta, babee!

As you can tell, it's a very effective system.

 

Hearing and the cochlea - Animation

Sound waves entering the ear travel through the external auditory canal before striking the eardrum and causing it to vibrate.

The eardrum is connected to the malleus, one of three small bones of the middle ear. Also called the hammer, it transmits sound vibrations to the incus, which passes them to the stapes. The stapes pushes in and out against a structure called the oval window. This action is passed onto the cochlea, a fluid-filled snail-like structure that contains the organ of Corti, the organ for hearing. It consists of tiny hair cells that line the cochlea. These cells translate vibrations into electrical impulses that are carried to the brain by sensory nerves.

In this cut-view, you can see the organ of Corti with its four rows of hair cells. There is an inner row on the left and three outer rows on the right.

Let's watch this process in action.First, the stapes rocks against the oval window. This transmits waves of sound through the cochlear fluid, sending the organ of Corti into motion.

Fibers near the upper end of the cochlea resonate to lower frequency sound. Those near the oval window respond to higher frequencies.

 

Seeing - Animation

Vision is the dominant sense for most people with sight.

The organ of sight is the eye. Think of it as a slightly irregular, hollow sphere that takes in light and translates it into images.If we enlarge the eye and look inside it, we can discover how that's done.

Inside the eye are various structures working together to create an image the brain can understand. Among these are the cornea, a clear dome-like structure covering the iris or colored part of the eye, the lens directly below it, and the retina, which lines the back of the eye. The retina consists of thin layers of light-sensitive tissue.

This candle can help us understand how the eye captures images and then sends them to the brain.First, the candlelight passes through the cornea. As it does, it's bent, or refracted, onto the lens. As the light passes through the lens, it's bent a second time. Finally, it arrives at the retina where an image is formed.

This double bending, though, has reversed the image and turned it upside down. If that was the end of the story, the world would always appear upside down. Fortunately, the image is turned right side up in the brain.

Before that can happen, the image needs to travel as impulses along the optic nerve and enter the brain's occipital lobe. When the image forms there, it regains its proper perspective.

Now let's consider two common conditions that cause blurry vision. The eye's shape is important for keeping things in focus. With normal vision, light focuses precisely on the retina at a location called the focal point.

But what happens if the eye is longer than normal? The longer the eye, the more distance there is between the lens and retina. But the cornea and lens still bend light the same way. That means the focal point will be somewhere in front of the retina rather than on it.

This makes it difficult to see things that are far away. A person with a long eye is said to be nearsighted. Glasses with concave lenses can correct nearsightedness.

The lens widens the plain of light coming through the cornea. That pushes the focal point back onto the retina.

Farsightedness is just the opposite. The eye's length is too short. When that happens, the focal point is behind the retina. So it's difficult to see things that are up close.

Glasses with convex lenses narrow the plain of light. Narrowing the light passing through the cornea moves the focal point back onto the retina and can correct farsightedness.

 

Tasting - Animation

The tongue has about 10,000 taste buds. The taste buds are linked to the brain by nerve fibers. Food particles are detected by the taste buds, which send nerve signals to the brain.

Certain areas of the tongue are more sensitive to certain tastes, like bitter at the back of the tongue, sour along either side toward the back, sweet on the front surface, or salty around the front edge. Often, taste sensations are a mixture of these qualities.

 

Smelling - Animation

As a person inhales, air and scent molecules move past the smell receptors in the nose. In turn, the smell receptors relay a signal to the brain. Smells can trigger memories and emotional responses.

 
 
 
 

 

 
 
 
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