Age-Related Changes to the Body’s Systems

By Maggie Norris, Donna Rae Siegfried

Life expectancy beyond the reproductive years is dependent to a great extent on genes. The developments of senescence (growing old) are gradual and diffuse. Body parts don’t work quite as well as they used to, and they just keep getting worse. For some people, this is a brief stage of life after a long, healthy middle age. Others aren’t so lucky.

In particular, the immune system doesn’t work as well as it used to, and malformed cells that would have been immediately eliminated at age 35 now may evade immune surveillance and become cancerous.

Age-related changes in the large arteries, as well as cumulative damage to the smaller vessels, can bring about problems with blood pressure.

Inactivity and chronic overconsumption of calories have their worst effects now, in all the major systems.

Still, the brain continues to develop. Research has been shown repeatedly that, under the right conditions, the brain continues to produce new cells and make new connections among neurons in adults as old as 100.

The table lists some of the common age-related changes to the body’s systems.

Age-Related Changes to the Body’s Systems and Associated Health Implications

Body System Change Implications
Cardiovascular system Heart increases in size. There is an increased risk of thrombosis (clotting) and heart attack.
Fat is deposited in and around the heart muscle. Varicose veins develop.
Heart valves thicken and stiffen. There is a rise in blood pressure.
Resting and maximum heart rates decrease.
Pumping capacity declines.
Arteries decrease in diameter and lose elasticity.
Digestive system Teeth may be lost. There is an increased risk of hiatal hernia, heartburn, peptic ulcers, constipation, hemorrhoids, and gallstones.
Peristalsis slows. Rates of colon cancer and pancreatic cancer increase in the elderly.
Pouches form in the intestines (in a condition known as diverticulosis).
Liver requires more time to metabolize alcohol and drugs.
Endocrine system Glands shrink with age, decreasing hormone release. Numerous homeostatic mechanisms are disrupted.
The metabolic rate decreases.
Lymphatic system Thymus gland shrinks with age. Cancer risk increases.
Number and effectiveness of T lymphocytes decrease with age. Infections are more common in elderly.
Autoimmune diseases (such as arthritis) increase.
Integumentary system Epidermal cells are replaced less frequently. The skin loosens and wrinkles.
Adipose tissue in face and hands decreases. Sensitivity to cold increases.
There is a loss and degeneration of fibers in dermis (collagen and elastin). The body is less able to adjust to increased temperature.
Fewer blood vessels and sweat glands are present. Hair grays and skin becomes paler.
Melanocytes decrease. Hair thins.
Number of hair follicles decreases.
Muscular system Muscle tissue deteriorates and is replaced by connective tissue or fat. The muscles lose strength.
Fewer mitochondria are in muscle cells. Endurance decreases due to fewer mitochondria.
Neuromuscular junction degenerates. There is a decrease in response and overall function.
Nervous system Brain cells die and are not replaced. Learning, memory, and reasoning decrease.
Cerebral cortex of the brain shrinks. Reflexes slow.
There is decreased production of neurotransmitters. Alzheimer’s disease occurs in elderly people.
There is a loss of sensory input (smell, vision, hearing, and so on).
Reproductive system Females: Menopause occurs between 45 and 55 years of age and causes cessation of ovarian and uterine cycles, so eggs are no longer released, and hormones such as estrogen and progesterone are no longer produced. Osteoporosis and wrinkling of skin occur, and there is an increased risk of heart attack.
Males: Possible decline in testosterone level after age 50; enlarged prostate gland; decreased sperm production. Impotence and decreased sex drive occur.
Respiratory system Breathing capacity declines. There is decreased efficiency of gas exchange.
Thickened capillaries, loss of elasticity in muscles of rib cage. Risk of infections such as pneumonia increases.
Skeletal system Cartilage calcifies, becoming hard and brittle. Bones become thinner and weaker.
Bone resorption occurs faster than creation of new bone (loss of bone matrix). More time is required for bones to heal if they break.
Osteoporosis risk increases.
Urinary system Kidney size and function decrease. Wastes build up in the blood.
There is decreased bladder capacity. Incontinence occurs.
The prostate gland in men is enlarged. The risk of kidney stones increases.
The urge to urinate is more frequent.
Urinary tract infections are more likely.