SECTION 1: SENSATION

People use their senses to negotiate the environment, protect themselves from danger, relate to another person, enjoy a pleasant experience, and discriminate between likes and dislikes. The process by which this occurs is based on stimulus picked up by sensory organs, transmitting signals to the brain, whereby the signals are interpreted and appropriate information sent back to various body parts resulting in some response to the original stimulus. The response can be in the form of some physical action, such as moving your hand abruptly away from a hot surface, or it can be in the form of an emotional response such as a sense of joy seeing your grandchild for the first time.

Senses become compromised due to normal physical changes that accompany aging. Since the amount and speed of change is different for each individual, the loss experienced is related to the amount of change. Of course, behavior and personality also determine the outcome of physical change. A person who loves bird-watching and dislikes music might cope well with a hearing loss, but may suffer great emotional upheaval at the loss of sight. The importance placed upon what is lost determines how the person handles the loss.

Sight

Everyone will experience some visual decline as they age. The most significant change that occurs is in the lens of the eye. The cells of the lens continue to grow throughout life, even though at a slower pace as one ages. The result is a thicker, and less elastic lens. During normal function the lens stretches flat to allow focusing on distant objects and relaxes to a round shape to enable focusing on near objects. The extra thickness decreases elasticity thereby impeding the ability to accommodate (the process of focusing the lens) to different distances. This age related condition which begins around the 4th decade is known as presbyopia. Having difficulty focusing on close and detailed work is usually viewed as an annoyance and solved with bifocal and trifocal lenses in glasses.

The lens also tends to yellow with age resulting in altered light transmission through the lens and impaired color perception. The darker violets, blues, and greens become hard to distinguish from one another. The lighter and brighter colors of yellows, reds and oranges are more easily seen.

The cornea, responsible for the refraction (directing the light appropriately to the retina) of incoming light, becomes flatter, thicker and less transparent. When this occurs, the lens then must make more adjustment to compensate. The aging changes to the lens impair this process, affecting visual acuity and compounding the visual problem from other sources.

The pupil is a muscular opening which dilates and constricts to control the amount of light entering the eye. With aging light movement into the eye is restricted because pupil size becomes smaller. In addition, an increasing weakness of the muscles responsible for the constriction (narrowing) and dilation (expansion) of the pupils occurs. These changes affect the ability to adapt one's vision to dim lighting or darkness.

The aqueous humor and vitreous humor are the fluid compartments of the eye providing support and nutrition to the eye. The fluid is continuously being made and the excess is normally reabsorbed. If the process of re-absorption becomes obstructed, then pressure increases inside the eye. An excess of pressure can damage the retina resulting in visual impairment or blindness. This condition of excess pressure in the eye is known as glaucoma.

Cataracts are the development of an opacity of the lens. The cause of this condition has not been absolutely defined. Aging appears to play a role, as well as some medical disorders and injury from environmental factors such as too much sun exposure. The severity of visual impairment relates to the severity of the cataract. Fortunately, current technology allows for the surgical removal of the lens and replacement with a synthetic lens restoring most times the eye to perfect vision.

THINK ABOUT IT:

Take a moment here and think about how these visual changes impact a person's ability to negotiate their environment

Older people in general require three times more light for visual perception than younger people. Unfortunately, increased light in itself can actually create more visual difficulty if not used properly. The major problem created by improper lighting is glare. Therefore, light is more effective when placed on the object rather than increasing the intensity of light in the entire room. It is also more effective if the light source is generated from behind the person instead of in front of them. Therefore, place a reading lamp directly over the shoulder of the person focusing the light down onto the reading surface.

A common problem for people with age-related visual problems is light entering from a window, causing a glare on the floor. Objects and steps become obscured from vision thereby increasing the risk of falls. The solution to this problem is the placement of a white sheer curtain over the window to allow adequate light while breaking any glare. One solution to decrease the glare of waxed floors is to use a low gloss or satin floor finish.

Another problem is the decreased ability to differentiate between dark colors and similar colors. Take, for example, a set of stairs outside a building painted all beige or all grey. Younger persons perceive where each step starts and ends because of the shading from shadows created by light. Older persons have lost that ability; and see a flat surface similar to a ramp. The solution is to paint the steps with altering light and dark colors or with altering bright colors. Also dark, non-slip strips can be applied to the edge of each light colored step.

Sound

Hearing is based on the ability of sound waves to be transmitted from the environment into the ear. The waves are transformed into electrical impulses which travel via nerves to the brain for interpretation. Any damage or blockage to parts of the ear along the path of sound waves interferes with sound transmission.

Presbycusis is the term associated with age-related hearing loss. It refers to the damage associated with excess environmental noise accumulated over a lifetime. Decreased efficiency of the cochlea and hair cells of the organ of Corti are the mechanical changes most common in causing presbycusis. The outcome is impaired ability to differentiate between high frequency sounds of consonants (f,g,s,z,t,sh, and ch). Therefore the vowel sounds dominate, resulting in difficulty understanding the spoken language. The ability to screen out background noises during normal conversation becomes increasingly difficult.

Another age related hearing problem is tinnitus, caused by damage to the otic nerve. The sounds are described as constant or recurring buzzing, clicking, or ringing in one or both ears. Tinnitus and general hearing loss can also be caused by medication, infection, head injury, or cerumen (earwax) accumulation in the ear.

Hearing ability directly relates to communication. The loss of hearing for elders can result in frustration and possibly threaten their sense of security and self-esteem. Most people have a tendency to become impatient with someone's inability to hear well and slowed communication. Exposure to that type of treatment over time tends to increase sensitivity and decrease interaction, and in some cases can lead to social isolation.

Some people can develop paranoid behaviors not associated with mental illness because of a hearing loss. This usually results from a sense of losing control over one's independence compounded by feeling those who have taken over that control may be talking about them to others behind their back. They actually see the people talking, are not able to hear the conversation, and imagine what the people are saying based on their fears. Sometimes the interpretation is exaggerated and far from reality. Care must be taken; just because someone cannot hear does not mean they are fading from reality.

Strategies for more effective communication with elders would include:

1. Speak slower, face to face, without any obstruction in front of your mouth. Many people talk while doing other activities, such as looking out a window or looking into a medical chart or magazine.

2. Never speak louder or yell. Most hearing loss only necessitates lowering the tone or deepening your voice while speaking slowly.

3. Try repeating your sentence using different words. Remember the difficulty of hearing high frequency sounds of consonants.

4. Reduce or eliminate background noise, such as TV, loud music, or intercom. Avoid being in room full of people in conversation such as a restaurant.

5. If you sense that the person may not be hearing you, ask if they have difficulty hearing and what you can do to accommodate them. For example, you might see the person turning their head so the better ear is facing you. You might even see a facial expression that indicates lack of understanding. And, of course, a big tip-off is inappropriate answers to your questions.

Taste

The quality and ability of taste discrimination tends to decline with age because of the decreased number and efficiency of the taste buds. The decline is not dramatic. It is dependent upon individual aging process, internal factors of decreased production of saliva, and external factors such as medications and smoking. For example, antihypertensive medications can increase one's ability to detect sour substances, whereas smoking tends to diminish taste perception overall. In general, the sense perception of sweet remains more intact than sour, bitter, and salty.

Smell

The sense of smell tends to diminish in proportion to the sense of taste; the cause is related to cell loss in the olfactory bulb of the brain and in the nasal lining. External factors such as exposure to long-term tobacco smoke and other toxic agents compounds changes in the sense of smell.

Touch

Touch perception or tactile sensitivity tends to decline with increasing age due to changes in skin and nerve endings. The areas most effected are the fingertips, palms of hands, and lower parts of the legs. Along with this is a diminished sensitivity to pain. Therefore perception of extremes of temperature from heating pads, heaters, and ice products can actually result in injury.

Kinesthetic sense or Proprioception

This sense is the ability to perceive one's own position in space. It includes the ability to determine if your position is upright from the floor, lying down, or tilted. As one ages, it becomes more difficult to orient oneself to changed body position. The older person will use more deliberate and precise movements. Automatic responses like reaching for a falling object become slower. Loss of balance may occur when attempting to avoid obstacles, such as in a crowded mall or street. Changes in a person's nervous system and muscles are the cause of this altered sense. Compounding these changes are diseases affecting mobility such as arthritic, heart disorders, stroke, and inner ear problems.

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SECTION 2: PROTECTION

The human body has its own system of protecting itself from potentially harmful effects of the external environment and of preventing the loss of essential parts and nutrients inside the body.

Skin (Integumentary System)

The integumentary system consists of skin, sebaceous (oil) glands, hair, and nails. The skin acts as a shield protecting the body from the extremes of temperature, pressure, and moisture, and provides a barrier to invading organisms. The skin also prevents the loss of water essential for homeostatic balance and aids in internal body temperature regulation. Vitamin D, necessary for calcium absorption, is synthesized upon skin exposure to ultraviolet light form the sun.

The skin consists of three layers. The outer tough layer (epidermis) provides protection from mechanical injury and pathogenic organism invasion. Melanin is a pigment produced in the epidermis to protect the skin from the damaging rays of sunlight. The middle dermis layer consists of blood vessels, nerves, hair follicles, sweat and sebaceous glands, and connective tissue. Sweat glands aid internal temperature control through the mechanism of sweating and evaporation of body water. Salt and other waste products are eliminated by sweating. Sebaceous oil glands lubricate skin and hair. The inner subcutaneous layer consists of fat cells for protecting internal organs and insulating against heat loss; blood vessels to supply nutrients and fluids to control body temperature; nerves to detect heat, cold, pain, touch, pressure; and collagen to provide support to skin tissue.

Nails serve to protect the ends of fingers and toes. Hair serves to insulate and protect certain body parts, as well as having sensory function.

The integumentary system changes with increasing age. In general the older adult tends to have dry, wrinkled, fragile, translucent skin with brown spots on exposed areas. Hair thins and becomes grey. The amount of change that occurs varies from individual to individual. Most age changes are influenced by heredity and hormone balance. Other changes we associate with aging are actually speeded up by long-term exposure to the sun and cigarette smoke.

Epidermal cells regenerate at a much slower rate resulting in slowed wound healing. Superficial capillaries within the skin become fragile with age, becoming susceptible to rupture resulting in easy bruising. The decreases blood flow from ruptured blood vessels interferes with the flow of nutrients necessary for wound healing. The amount of collagen decreases over time leaving the skin less elastic and more susceptible to tears. Due to the less elastic nature, skin tends to reflect life patterns of muscle activity specifically in facial expressions. The result we see are wrinkles.

The activity of sebaceous glands diminish with age resulting in dry and more fragile skin and hair. Subcutaneous fat decreases resulting in a thinner dermis and translucent appearance of skin. The additional decrease in body hair, sweat production, and blood supply to the skin results in impaired ability to perceive changes and extremes of temperature as well as impaired ability to withstand extremes of temperature.

As the skin ages, there is a general decreased melanin production. The exception is that some areas of skin exposed to light actually have increased melanin synthesis appearing as pigment spots usually called 'liver spots'. It has been suggested that decreased melanin production in hair follicles causes grey hair.

Nails generally grow at a slower rate, becoming thicker and sometimes more fragile.

Immunity

Human immunity is based on two types of defense activities. The first activity is to prevent the invasion of microorganisms and foreign objects from entering the body. The skin is the body's first line of defense, providing a barrier between the external and internal environment. Many organs have their own first line of defense when microorganisms enter through a natural opening. Stomach acid and the enzymes found in the mouth, nose and vagina tend to destroy the invading organisms. Once organisms find their way into the blood stream, they are usually caught by the filtering activity of the liver, spleen, and lymph nodes.

The second and most important line of defense is the body's ability to fend off the attack once infected. This occurs from the immune activity of white blood cells circulating throughout the body with the function of detecting, immobilizing, and removing foreign invaders. The white blood cells involved in this type of immunity are called T and B cell lymphocytes and macrophages.

T cells are white blood cells called lymphocytes that play a role in switching the immune response on and off. There are three types of T cells, T Suppressor, T Killer, and T Helper cells. As we age there is a decrease in T-suppressor cell activity, those cells that keep the immune response from attacking the body's own cells. Research suggests this leads to autoimmune diseases such as arthritis and cancer.  

There does not appear to be any change in T-killer cells, those cells that attack bacteria and other foreign cells. There appears to be only a minor decrease in the number of T-helper cells, those that assist B cell function.

B cells are lymphocytes responsible for producing antibodies that bind to foreign substances such as bacteria and viruses. This binding process targets the foreign substance for destruction. The antibodies remain circulating in the body to protect against any future invasion of the same intruder. The ability to produce B cells appears to remain the same into older age, but the response to foreign substances may be less aggressive.

Macrophages are white blood cells that engulf and digest foreign invaders. There are no discernible changes in number, size or activity related to age.

As a general rule, the overall efficiency of the immune response declines with advancing age. Our immune system becomes less able to prevent and fight off infection. It also becomes less efficient at knowing the difference between the body and a foreign invader.

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SECTION 3: BALANCE

This section represents the discussion of organs and systems that play an integral part in ensuring proper fluid and chemical balance necessary for the human body to function. This process of balance relies upon a complex connection with other organ systems.

Kidneys/Bladder

Two kidneys and a bladder are the organs that comprise the urinary (Renal) system in the human body. The function of the urinary system to regulate the composition of body fluids, and rid the body of certain waste products and toxic substances in the body fluid. Through selective filtering, the kidneys remove waste from the blood, returning the water and needed nutrients back into the blood system. There is a very complex and efficient system of regulating the balance of water and nutrients in the body. Anything dramatically affecting that balance such as illness, disease, or injury can have life-threatening consequences.

After the process of filtering, some of the water with the waste products becomes urine, and is transported to the bladder. The bladder is an expandable storage organ for urine, emptied normally upon voluntary relaxation of a sphincter muscle at the opening.

The functional unit of the kidney where the complex task of filtering occurs is called a nephron. There are approximately one million nephrons in each kidney. Kidney function is not isolated, rather is based on complex interrelationship with the adrenals, the hypothalamus, and the pituitary gland. The relationship depends on a communication link comprised of specific regulating chemicals. In addition to the filtration process, specific enzymes (renin), blood proteins (angiotensin I and II), steroid hormones (aldosterone, ADH or vasopressin) and salts (sodium) regulate blood pressure and blood volume.

Age related changes in the urinary system include a general 20% loss in weight of the kidney. The change possibly is due to a decrease in the number of nephrons. There is also decreased blood flow to the kidneys, most likely the result of decreased cardiac output related to aging. Even though there are structural changes due to aging, the result is only a decline in filtering efficiency. The actual function of the kidneys remains the same in the absence of disease.

The impact of these changes are seen during periods of stress or dehydration. The older adult may have a more difficult time preserving necessary body water from the inability or slowness of the kidneys to concentrate urine. Therefore, excess water is lost through urination. The impact is also seen with drug therapy. Drugs that are excreted by the kidneys stay in the body longer due to the decreased efficiency. It is not that the kidneys can not break them down, rather it takes longer. This results in drugs staying in the circulation longer and accumulating from multiple doses to sometimes dangerously toxic levels. Therefore, the dosage of drugs administered to anyone over sixty needs to be adjusted for age.

Age related changes to the bladder are more functional than structural. In general, the older adult bladder holds less urine than the younger adult bladder leading to a need for more frequent urination. A younger person's brain receives a signal from sensory receptors in the wall of the bladder when it is about half full; it gives one time between receiving the signal and experiencing the need to void the bladder of urine. As adults age this neural signal is late or non-existent resulting in urgency, anxiety, and even accidents.

Liver (Hepatic System)

The liver is the largest organ in the human body. It receives deoxygenated blood via the portal vein from the pancreas, spleen, stomach, intestines, and gallbladder. The liver also receives oxygenated blood from the aorta via the hepatic artery. Nutrients, metabolites, and toxins are transported to the liver for processing, detoxification, or assimilation. The liver must breakdown, form, convert, store, and remove various compounds to maintain an essential balance for healthy functioning.  

Age related changes to the liver are minimal. Even though there are some minor structural changes, the liver can maintain its performance barring any damage from disease or alcoholism.

Spleen

Since the spleen is considered a lymphatic organ, its function will be discussed in more detail in Part III. One major function of the spleen is to maintain a homeostatic balance by acting as a storage unit for excess blood. Upon need of extra blood in exercise or injury, the spleen transfers its stores into the circulation.

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SECTION 4: PROCESS

This section discusses the organ systems that play an integral role in processing the food and fluid ingested into the human body. Process involves the breakdown and assimilation of usable nutrients necessary for life, and the elimination of waste byproducts.

The digestive or gastrointestinal system process begins with food and fluids entering the mouth making a downward passage through the stomach and intestines. The teeth, salivary glands, gallbladder, liver and pancreas break down the ingested material so necessary nutrients, water, and energy can be absorbed into the bloodstream and used by the cells. The byproducts of processing and indigestible materials are then eliminated through the end part of the large intestine called the rectum.

Age-related changes in the digestive system are somewhat complicated by problems that may be more associated with disease and lifestyle habits than age. For instance, the only true age related alteration in the mouth is a potential 25% reduction in saliva production resulting from the growth of fibrous or fatty material infiltrating secretory cells of the salivary glands. This change has been related to aging rather than disease, but like other age-related changes in the body this occurrence varies from person to person. The result of this change is dryness of the mouth. Dry mouth (Xerostomia) is also a side effect of many medications, the most common being antihypertensives, antihistamines, and antidepressants. Illnesses such as emphysema, or allergy causing sinus symptoms results in dry mouth from mouth breathing. Dry mouth is a common complaint in postmenopausal women, most likely due to decreased production of estrogen hormones.

Dry mouth can interfere with proper breakdown of foods in the mouth, the first phase of the digestive process. The problem can be further complicated by dental problems. Worn down teeth from years of chewing interferes itself with the initial breakdown of food, without the added complication of a lack of needed mouth moisture from dry mouth. Dental health has been shown to be more related to lifestyle than age; the type of foods eaten, the type of care and cleaning provided over the years, the loss of teeth, and bone condition will determine how well a mouth will function in later years. We can say that the effectiveness of mouth function directly affects the digestive process and therefore impacts nutritional status. We cannot relate these problems directly to age, rather to use and misuse.

Peristaltic motion in the digestive system tends to slow with age. This motion is needed to move swallowed food down through the esophagus and into the stomach. Dry mouth and ineffective chewing leads to larger pieces of unprocessed food being swallowed. Add slowed motility and the result can be seen as heartburn, reflux, or hiatal hernia.

Pepsin and hydrochloric acid production in the stomach tends to decline around middle age and then remain the same into older age. Since pepsin and hydrochloric acid are needed to breakdown proteins, a reduction results in the slower process of food breakdown and the symptom of indigestion.

A reduced blood flow to the lining (mucosa) of the intestines can result in reduced absorption of needed vitamins and minerals such as calcium, B1 and B12, and iron. Appropriate dietary intake can avert problems in this area. Slowed peristaltic motion of the intestines may be accompanied by slowed activity levels. Waste material then moves slower, spending more time in the intestines, and allowing more water to be absorbed from the waste material. The result is harder feces and constipation, a common complaint of elders.

Age does not appear to affect the function of the gallbladder, liver, or pancreas as related to digestion.

Overall, the major function of the digestive system is in the absorption of needed nutrients. In order for anything to be absorbed, it must be digested first. The effects of aging slows the speed and thoroughness of digestion, impairs the absorbing surface integrity, and slows the mechanisms of transport through the system.

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