Aging has measurable effects on all body parts — including the heart, the bones, the mind — particularly if you don't take care of yourself. The aging process also affects the five senses. The ability to see and hear clearly and to taste and smell usually declines as people age. Sensory loss of any kind, if not corrected or minimized, can adversely affect your overall health and well-being.

The inability to see clearly, for example, can lead to a host of other problems, ranging from social isolation to injuries from falls. Such injuries may require hospitalization. Or worse, they may lead to serious health complications, which can cause further disability.

Likewise, an older individual with a hearing problem is more likely to become less physically mobile, less cognitively curious, less communicative and less social.

If you have trouble tasting or smelling pleasurable aromas, you may lose interest in food and develop a poor appetite. This can put you at risk of poor nutrition. Hygiene may be affected if you can't detect unpleasant body odor. And safety is a concern if scents from harmful vapors or gases or smoke from a fire go unnoticed.

Like the aging process itself, the speed and the degree to which your senses decline in later life are highly individual. Genetics, the environment and your lifestyle all play a role.

The good news is that many types of sensory losses can be corrected or improved with medical and surgical intervention and/or help aids and devices, such as eyeglasses, hearing aids and telephone amplifiers. So be sure to speak with your health-care provider if you are suffering from any change in vision, hearing, taste, smell or touch.

Vision is the process in which light waves from an object being looked at are registered, interpreted and stored as an image by the brain. For this to happen, the light waves pass through the cornea, pupil and lens of the eye. The light waves are then projected onto the retina, which is located at the back of the eye. The optic nerve behind the retina picks up the signals from the nerve endings in the retina and relays them to parts of the brain that process the image and make it recognizable.

Various malfunctions in the process of vision may occur as a person ages. They may be caused by:

Reduced muscle tone. The muscles that control movement of the eyes can malfunction with age. More commonly, the muscles that support the skin around the eye sockets and control the upper and lower eyelids may become too relaxed or weak and lose their firmness and elasticity. Over time, they become flaccid, causing the supporting connective tissue and skin around the eyes to droop and sag in ever-thickening folds.

This decrease in muscle tone and functioning can lead to a number of conditions in the aging eye, although these conditions are not always caused by aging. Most prominent among these conditions is blepharoptosis, or ptosis — a marked drooping of the upper eyelid. If left untreated, ptosis may impair vision and can lead to headaches and fatigue.

Decreased eye lubrication. The lacrimal gland in the eye produces protective tears with each blink. These tears keep the eye clean and lubricated. With age, the gland may start to malfunction, decreasing tear production. This can lead to burning, itchy eyes and other eye irritation.

A common problem that can develop as the eye ages is dry eye syndrome, in which the protective tear film that coats the eye dries too rapidly. And because tear production diminishes with age, replenishment of this tear film is insufficient.

Eye disorders or diseases. Vision problems may result when various structures in the eye deteriorate or become diseased. The pupil gets smaller — as much as a third of its size by age 60 according to one estimate — altering how (and how much) light passes through it.

Here are the eye disorders and diseases that most commonly occur with age:

To reduce your chances of developing any of these problems at a younger age, it is important that you have regular eye examinations beginning at age 40.

The process of hearing starts when sound waves travel into the ear and bounce off the eardrum, causing it to vibrate. The vibrations travel along three tiny bones in the middle ear, and then move deeper into the inner ear where they are transformed into nerve impulses or signals. The auditory nerve picks up the signals and zips them on to the brain to be interpreted.

In later life, some degree of hearing loss is pretty much inevitable as the intricate structures and nerve network in the middle and inner ear slowly begin to break down. The auditory nerve itself can undergo changes related to aging, leading to interpretation changes.

Some common age-related hearing problems include:

Certain risk factors may play a role in the onset of hearing problems in the older population. They include chronic exposure to loud sounds, smoking and numerous middle ear infections. If you notice any change in your hearing, it is important that you undergo a comprehensive hearing test.

Taste and smell are two separate and distinct senses that often work together for different purposes. They can detect pleasurable sensations or warn a person of danger. They also play an important role in the acceptance and enjoyment of food — the fuel needed to maintain optimal health and functioning.

As the body ages, the keenness of taste and smell naturally diminishes. Even so, research now suggests that aging alone may not be solely responsible.

Changes in taste. Taste occurs when molecules from food or liquid latch on to even smaller receptor cells found on the thousands of tastes buds that cover the tongue. Specialized nerves pick up signals from the receptor cells and transmit them along to the brain, which then identifies and recognizes these signals as flavor. Taste buds can recognize some 10,000 different flavors. Attached to each taste bud are flavor-receiving cells that every 10 days are replaced with fresh new cells.

The sense of taste diminishes with age. In general, older people need more concentrated sweets to taste sweetness and a less intense sour flavor to taste sourness. Although it's not precisely clear how this happens, one theory is that the production of saliva decreases. This, in turn, can cause a condition called dry mouth, which can reduce taste perception. Some experts argue, however, that dry mouth is not a given in old age and that a healthy elderly person can produce as much saliva as a younger person.

There's general agreement, however, that a host of other factors can interfere with the sense of taste in older people. These factors include:

Diseases affecting the mouth (for example, periodontal disease) can alter the sense of taste in later years, as can diseases affecting other parts of the body (such as diabetes, cancer, thyroid disease, stroke and other neurological conditions).

A diminished sense of taste can lead to poor appetite and nutrition. A person suffering from a deficiency in taste might unwittingly eat contaminated or spoiled food that puts them at risk of food poisoning or other illnesses.

It is important to maintain good oral care throughout life to ward off any problems that could lead to a diminished sense of taste.

Changes in smell. The sense of smell identifies and distinguishes aromas and odors. It works in sync with the sense of taste in detecting food that is safe for human consumption and also enjoyable. Smell is made possible when molecules from food are breathed in through each nostril in the nose. These molecules latch on to specialized receptor cells that send signals to a specialized area of the brain for identification and recognition.

But the keenness of smell diminishes faster with age than does the keenness of taste. During a person's 50s, the decline is pretty rapid. In the average octogenarian, the sense of smell is half as sharp as it was during his or her youth.

Like taste, smell can be affected by a host of factors:

You may want to talk with your health care professional if you find that age-related changes in smell are affecting your quality of life or your safety.

When you touch something or someone, or something or someone touches you, the sensation — be it hot or cold, hard or soft, pleasurable or painful — is picked up as signals by a network of superficial nerves. These nerves (called neurons) transmit the signals to nerve receptors in the central nervous system. From the central nervous system, the signals are relayed to the brain, which analyzes and interprets them.

In later life, the sense of touch may become less sensitive. There are a number of reasons why this occurs. First, the outer skin (or epidermis) takes a beating. After all, it's the first line of defense against disease, contaminants, harmful rays from the sun, wind, heat and cold.

The years are also not kind to the deeper, dermis layer of the skin. For example, elastin and collagen found in the dermis begin to deteriorate. These two substances give the skin its elasticity and softness.

These changes, working in concert, can cause aging skin to become dryer, thinner, less elastic and less supple, sometimes reducing an older person's sensitivity to certain pressure and vibrations. There can be a change in temperature sensitivity, too. A person may feel colder overall, but may have more trouble distinguishing between an object that is cold vs. cool.

Other health problems, prevalent among older adults, also may explain changes in the sense of touch. These include:

A diminished sense of touch may put older individuals at an increased risk of sustaining serious injuries, such as pressure sores, skin ulcers, heat stroke, burns and hypothermia (abnormally low body temperature).