PHYSIOLOGY OF AGING

by Mary S. Kaufmann, M.A.

"Out of sight - out of mind," an adage most of us have heard. Perhaps that is why too many people don't recognize the impact their lifestyle has on their body, externally and internally. Physical activity has been shown to have protective effects for coronary hart disease, hypertension, non-insulin dependent diabetes, osteoporosis, colon cancer, depression and anxiety. Yet among women over the age of 65, about 48% do not exercise as all. Projections show that there would be 11% fewer deaths in 20 years if all U.S. smokers stopped smoking. Dietary information is readily available, and low-fat and non-fat products are heavily promoted, to a tune of $33 billion a year in purchases. Yet obesity is actually on the rise! The National Center for Health Statistics reports 35% of females and 31% of males age 20 and older are considered obese (up from 30% and 25% in 1980.)

In honor of World Health Day (April 7, 1999), President Clinton made the following comments: "To ensure good health in later years we must prepare ourselves by following such commonsense steps as maintaining a healthy diet, exercising regularly, seeing a health care provider who is knowledgeable about healthy aging, keeping our minds active, participating in the life of our communities, and making informed decisions regarding finances, future living arrangements and the possible need eventually for long term care in the advanced years."

We al need to consider a new mind set about aging. Aging is not an inevitable process leading to disease and deterioration. We each can influence our quality of life by making health lifestyle choices -- at all ages!

Internal Changes:

HEART: As the heart ages some changes become evident. There are fewer heartbeats, they are more irregular, and the overall blood volume output and muscle strength decreases.

The left ventricular cavity, which pumps the blood and oxygen to the body may decrease in size due to less activity, malnourishment, being confined to bed or recuperating from an extended illness. The amount of oxygen moving in and out of the lungs and to the muscles may decrease 40% between the ages of 30 and 65.

The aorta that receives the blood from the heart on its way to all parts of the body, begins to shrink and lose some of its elasticity--perhaps as much as 50% in comparing a 70 year-old with a 20 year- old male. Decreased blood to the heart can cause chest pains and shortness of breath.

The cardiac muscle progressively decreases in size and strength and as it pumps less, the amount of blood flow throughout the body is slowed to about 70% that of a 30 year-old. Working harder and accomplishing less shows up in increased blood pressure in 30% of those over age 65.

These changes also decrease the heart's ability to respond to stress. Often the drug digitalis is used to give the heart muscle a boost by stimulating heart muscle contractions. Major heart problems are: coronary artery disease (or ischemic heart disease), atherosclerosis (narrowing or arteries), arteriosclerosis (hardening of the arteries), congestive heart failure, and strokes. If you suspect a heart attack, immediately chew an aspirin and go immediately to a hospital.

URINARY SYSTEM: The kidneys filter and remove wastes, and maintain proper blood composition. Although kidney function declines with age, it does not cause any major problems unless it is severely restricted in the amount of blood it receives because of heart problems.

The bladder, however, has a capacity of less than half (250 ml) that of a young adult (600 ml). In addition it may retain 100 ml, further decreasing its overall capacity. Often the desire to urinate is not communicated until the bladder is near capacity, versus when half full at a younger age. Although incontinence may not result, the frequency and urgency feelings may be frustrating. Total incontinence affects approximately 15% of those over age 65, peaking in the 80's. It is estimated 60% of those over 65 who are institutionalized are incontinent, and may be one of the primary reasons for placement.

Bladder problems may be a result of 1) weakness in bladder outlet (strained during childbirth), 2) over activity of the entire bladder mechanism, 3) contractions failing to empty bladder or 4) bladder so distended there is continuous leakage. In older men, enlargement of the prostate gland can increase frequency or loss of control. There are now special programs to help one overcome these problems, using such techniques as biofeedback and exercise.

DIGESTIVE SYSTEM: This encompasses the mouth, esophagus, stomach, intestines and rectum. One thing which affects the digestive system is nutrition. Often seniors don't eat properly because they have periodontal disease, have no teeth or dentures, or have bad dentures which makes it hard to chew. By age 75, 50% of seniors have dentures with 75% of teeth lost to periodontal disease. No dental coverage is provided by Medicare and high costs deter seeking proper care.

There is an increase in hiatal hernias where the esophagus and diaphragm join and an increase in cancer of the esophagus, which is deadly. A decrease in digestive enzymes and the beginning of atrophy of glands in the stomach causes food to move slower through the digestive tract. The internal walls of the intestines have pouches which can catch food, become infected (diverticulitis), and rupture. Cancer of the small intensive also becomes more common and deadly. Although it is more likely to develop cancer in the large intestine, it can be treated.

RESPIRATORY SYSTEM: The bronchial system is like a tree. There is a main bronchial tube branching off into the lungs and at the end of the lungs there are alveoli (like leaves on a tree). The whole tree becomes less elastic as you age. There is a decrease in the alveoli surfaces after age 20 of 3 square foot/year. There is a decrease in blood flow so there is less exchange of oxygen and carbon dioxide in the lungs as we grow older. With 40% less air moving in and out of the lungs, it is harder to cough and so one is more susceptible to bronchial infections and pneumonia. Seniors should practice deep breathing, drink more water, stop smoking, stay away from fumes, dust and air pollution and see a doctor if there is a lung infection. Pneumonia, which is an accumulation of fluids in the alveoli so that exchange of oxygen is impossible, can be brought on by getting an aspirin caught in the windpipe. Major disease is COPD (Chronic Obstructive Pulmonary Disease) which includes chronic bronchitis, emphysema, and asthma. Other acute respiratory disorders would be tuberculosis, flu and pneumonia. COPD is the fourth leading cause of death for seniors.

ENDOCRINE SYSTEM: The endocrine system consists of a variety of glands, primarily the pituitary, thyroid and adrenal glands. They maintain homeostasis (balance) through hormone release. If there is too much of something, then a hormone is released to return our system to normal.

One of the main changes handled by this system is the change in the reproductive system. In females, there is a very abrupt decrease in estrogen. Until recently there were few studies on menopause. The Women's Health Initiative will study 164,500 women of various racial and ethnic backgrounds through 2005. They expect to find out whether a low-fat, hormone replacement therapy, calcium and vitamin D might prevent heart disease, breast and colorectal cancers, bone fractures and memory loss.

The male reproductive system peaks early and the sperm count may gradually disappear but otherwise there are minimal changes in their abilities for sexual relationships.

The pea-sized pituitary gland is located at the base of the brain. It is considered the master gland because the hormones it produces stimulate other endocrine glands. There are two lobes, a posterior and anterior lobe, and each one releases hormones that cause different reactions, such as controlling the growth hormones and stimulating cell division in tissues such as bone and cartilage.

There are two adrenal glands and they are positioned above the kidneys. The cortex region of this gland produces hormones involved in metabolism and the suppression of inflammatory responses and helps regulate urine secretion, blood volume and pressure. The medulla region provides hormones that respond to stress, fear or exertion and can quicken heart rate, increase blood flow, widen lung airways and draw blood away from internal organs and channel it to muscles in support of either "fight or flight."

The thyroid is somewhat susceptible to aging. It is located just below the larynx and manufactures two hormones that regulate metabolism and one that regulates calcium balance. This gland is a kind of throttle for the body. As it releases more hormones, the body runs faster and as the hormone decreases, the body slows down. Thyroid problems are common among seniors but are hard to recognize because the symptoms develop slowly. If one develops hyperthyroidism (too much production), some symptoms are weight loss, intolerance of heat, alternating constipation and diarrhea, rapid pulse and night sweats. Too little production results in hypothyroidism. Both conditions are readily treated with medication. Females over 65 should have an annual blood test; men are not as prone but should be checked every five years.

The long, tapered pancreas lies beneath and behind the stomach, near the small intestine. It produces insulin. When it malfunctions, it can lead to diabetes. Five percent of the entire population have diabetes; 20% of all diabetics are 60 years or older and have what is termed "adult onset" diabetes. Diabetes can be controlled by diet, but not cured. More severe cases require injections. Complications are common. The reduced blood supply contributes to circulation and vision problems.

NERVOUS SYSTEM: The brain is the most incredible computer that exists. We are born with all the brain neurons--about 100 billion nerve cells--that we will ever have. This network performs communication within the brain and to the rest of the body. A future issue will discuss the brain, how it works and why, sometimes, it doesn't work.