Aging changes in organs, tissues, and cells
Information:
BACKGROUND
Most people realize that vital organs begin to lose function with aging. Aging changes have been seen in all of the body's cells, tissues, and organs. These changes affect the functioning of all body systems.
Living tissue is made up of cells. There are many different types of cells, but all have the same basic structure. Tissues are layers of similar cells that perform a specific function. The various kinds of tissue group together to form organs.
There are 4 basic types of tissue: connective tissue, epithelial tissue, muscle tissue, and nervous tissue. Connective tissue supports other tissues and binds them together. This includes bone, blood, and lymph tissues in addition to the tissues that give support and structure to the skin and internal organs. Epithelial tissue provides a covering. It includes the skin, and the linings of the various passages inside the body. Muscle tissue includes striated (also called voluntary) muscles that move the skeleton. It also includes smooth muscle, such as the muscles that surround the stomach. Nerve tissue is made up of nerve cells (neurons) and is used to carry "messages" to and from various parts of the body.
AGING CHANGES
All cells will experience changes with aging. The cells become larger, and are less able to divide and reproduce. Among other changes, there is an increase in pigments and fatty substances inside the cell (lipids). Many cells lose their ability to function, or begin to function abnormally.
General tissue aging changes include an accumulation of waste products in the tissue. A fatty brown pigment called lipofuscion collects in many tissues, as do other fatty substances. The connective tissue changes, becoming increasingly stiff. This makes the organs, blood vessels, and airways more rigid. Cell membranes change, so many tissues have more trouble getting needed oxygen and nutrients, and getting rid of carbon dioxide and wastes.
Many tissues lose mass (a process called atrophy). Some tissues become lumpy (nodular), more rigid, or have other changes.
Because of cell and tissue changes, the organs also change with aging. Aging organs gradually but progressively lose function, and there is a decrease in the maximum functioning capacity. This loss is usually not noticed, because we seldom need to use our organs to the fullest capability.
Organ reserve is the "extra" ability that organs have above the usual needs. For example, when we are young our heart is capable of pumping about 10 times the amount that is actually needed to preserve life. After age 30, an average of 1% of this reserve is lost each year. Other organs also lose organ reserve. The most significant changes are in the heart, lungs, and kidneys. The amount of reserve lost varies between people and between different organs in a single person.
These changes appear slowly and over a long period of time. Even so, when an organ is worked harder than usual it may not be able to increase function. Sudden heart failure or other problems can develop when the body is worked harder. Things that produce an extra workload (body "stressors") include certain medications, illness, significant life changes, suddenly increased physical demands on the body (such as a sudden change in activity or exposure to a higher altitude), and similar events.
Loss of reserve also makes it harder to restore equilibrium in the body. Drugs are detoxified at a slower rate. So, lower doses of medications may be needed, and side effects become more common. Medications side effects can mimic the symptoms of many diseases, so it is easy to mistake a drug reaction for an illness. Some medications have entirely different side effects in the elderly than in younger people.
AGING THEORY
No one really knows how and why people change as they get older. Some theories claim that aging is caused by accumulated injuries from ultraviolet light, "wear and tear" on the body, byproducts of metabolism, and so on. Other theories view aging as a predetermined, genetically-controlled process.
However, no theory sufficiently explains all the changes of the aging process. Aging is a complex and varied process that varies in how it affects different people and organs. Most of the people who study aging (called gerontologists) feel that aging is the cumulative effect of the interaction of many lifelong influences. Things that affect the aging process include heredity, environment, cultural influences, diet, exercise and leisure, past illnesses, and many other factors.
Unlike the changes of adolescence, which are predictable to within a few years, each person ages at a unique rate. Some systems begin aging as early as 30 years old. Other aging processes are not common until much later. Although there are changes that typically occur with aging, they occur at different rates and to different extents. There is no reliable way to predict specifically how you will age, including your age in years (chronological age). In fact, even in one person different organ systems "age" at a different rate.
TERMS- ATROPHY
- Cells shrink. If enough cells decrease in size, the entire organ atrophies. This is often a normal aging change and can occur in any tissue. It is most common in skeletal muscle, the heart, the brain, and the secondary sex organs (such as the breasts). The cause of atrophy is unknown, but may include reduce use, decreased workload, decreased blood supply or nutrition to the cells, and reduced stimulation by nerves or hormones.
- HYPERTROPHY
- Cells enlarge. This size increase is caused by an increase in cellular proteins, such as the cell wall and internal cell structures, NOT an increase in the cell's fluid. When some cells atrophy, others may hypertrophy in an attempt to compensate for loss of cell mass.
- HYPERPLASIA
- The number of cells increase. There is an increased rate of cell division. Hyperplasia usually occurs in an attempt to compensate for loss of cells. It allows some organs and tissues to regenerate, including the skin, the lining of the intestines, the liver, and the bone marrow. The liver is especially good at regeneration. It can replace up to 70% of its structure within 2 weeks after an injury.
- Tissues that have limited ability to regenerate include bone, cartilage, and smooth muscle (such as the muscles around the intestines). Tissues that seldom or never regenerate include nerves, skeletal muscle, heart muscle, and the lens of the eye. When injured, these are replaced with scar tissue.
- DYSPLASIA
- The size, shape, or organization of mature cells becomes abnormal. This is also called atypical hyperplasia. Dysplasia is fairly common in the cells of the cervix and the lining of the respiratory tract.
- NEOPLASIA
- The formation of cancerous, malignant tumors. This may be an extension of the processes causing hyperplasia and hypertrophy. The cells reproduce rapidly; they may have unusual shapes and abnormal function.
RELATED TOPICS
aging changes in hormone production
aging changes in immunity
aging changes in the skin
aging changes in sleep
aging changes in the bones, muscles, and joints
aging changes in the breast
aging changes in the face
aging changes in the female reproductive system
aging changes in the heart and blood vessels
aging changes in the kidneys
aging changes in the lungs
aging changes in the male reproductive system
aging changes in the nervous system
Also
+ the drug document about medications in the elderly
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The information provided herein should not be used for diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Copyright 2000 adam.com, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
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