ch05 nutrition and theories of aging

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Theories of Aging

Objectives This presentation will describe aging from both a biological/physiological and a psychosocial perspective. Biological/physiological theories will be presented in two main categories, program theories and error theories. Psychosocial theories will be discussed in two main categories, full-life theories and mature-life theories.Gerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

What is Aging?The gradual and spontaneous changes that occur in maturation from infant to young adult. These changes create a normal physiologic decline seen in middle and late adulthood. Changes during puberty Graying of hairGerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

SenescenceThe process by which a cell looses its ability to divide, grow, and function. This loss of function ultimately ends in death. A degenerative process, only. Has no positive features.

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Theories of AgingThe link between genes and lifespan is unquestioned. The simple observation that some species live longer than others -humans longer than dogs, tortoises longer than mice -- is one convincing piece of evidence.The National Institute on AgingGerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Theories of Aging All aging begins with genetics Aging changes the biochemical and physiological processes in the body Cell and molecular biologists examine and propose theories to explain the aging process What causes aging? How can you influence aging prolong life?Gerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

The Two Main Aging Theory Categories Programmed Theories Aging has a biological timetable or internal biological clock. Error Theories Aging is a result of internal or external assaults that damage cells or organs so they can no longer function properly. Many theories are a combination of programmed and error theories.Gerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Programmed vs. Error TheoriesProgrammed Theories

Programmed Senescence Theory Endocrine Theory Immunology Theory

Error Theories Wear and Tear Theory Rate-of-Living Theory Cross-linking Theory Free Radical Theory Error CatastropheTheory Somatic Mutation TheoryCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Gerontological Nursing, Second Edition Patricia A. Tabloski

Programmed TheoriesProgrammed Senescence Theory Endocrine Theory Immunology Theory

Programmed Senescence Theory The result of sequential switching off or on of specific genes.

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Telomeric Theory Telomeres are specialized DNA sequences at the end of chromosomes. They shorten with each cell division. When the telomeres become too short, the cell enters the senescence stage.

In the normal process of DNA replication, the end of the chromosome is not copied exactly, which leaves an unreplicated gap.

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Telomeric Theory The enzyme, telomerase, fills the gap by attaching bases to the end of the chromosomes. As long as the cells have enough telomerase to do the job, they keep the telomeres long enough to prevent any important information from being lost as they go through each replication. With time, telomerase levels decrease. With decreasing telomerase levels, the telomeres become shorter and shorter.Gerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Telomeric TheoryShortened telomeres are found in: Atherosclerosis Heart disease Hepatitis Cirrhosis

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Telomeric Theory and Cancer 90% of cancer cells have been found to possess telomerase. Telomerase prevents the telomere from shortening. This allows the cancer cells to reproduce, resulting in tumor growth.

Research areas Measuring telomerase may help detect cancer. Stopping telomerase may fight cancer by causing death of cancer cells. Telomerase may be used to help with wound healing or the immune response.Gerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Endocrine Theory Biological clocks act through hormones to control the pace of aging. Hormones effects growth, metabolism, temperature, inflammation and stress. Examples- Menopause Decreased level of estrogen & progesterone Hot flashes, insomnia

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Immunologic Theory A programmed decline in the immune system leads to an increased vulnerability to disease, aging and death Example- Decreased T cells (helper cells) in adults Increased diseases in older adults Increased autoimmune diseases in adults

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Error TheoriesWear and Tear Theory Error Free Radical Theory Rate-of-Living Theory CatastropheTheory Cross-linking Theory Somatic Mutation Theory

Wear and Tear Theory Years of damage to cells, tissues and organs eventually wears them out, killing both them and the body Example- Wearing out of the skeletal system such as in osteoarthritis Wear and tear can be viewed as a result of aging and not the cause of it.

Gerontological Nursing, Second Edition Patricia A. Tabloski

Copyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Rate-of-Living Theory

The greater an organisms basal metabolic rate, the shorter the life span. Free radicals or other metabolic byproducts play a role in senesce. Example Animals with the most rapid metabolisms tend to have the shortest lifespans, i.e, birds have a shorter lifespan than humans. Studies examining the relationship between metabolic rates and longevity have produced inconsistent results, limiting the usefulness of this theory.Gerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Cross-Linking Theory The accumulation of cross-linked proteins damages cells and tissue, slowing down bodily processes. Example Non-enzymatic glycosylation reactions occur when glucose molecules attach to proteins causing a chain of chemical reactions resulting in a structural change to the proteins. Loss of flexibility of connective tissue Microvascular changes in arteriesGerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Free Radical Theory During aging, damage produced by free radicals cause cells and organs to stop functioning. A free radical is a molecule with an unpaired, highly reactive electron. One type of very reactive free radical is the oxygen free radical, which may be produced during metabolism or as a result of environmental pollution.Oxygen free radicals are formed in your cells, naturally, during the oxidation of food to water and carbon dioxide.Gerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Free Radical TheoryThe free radical grabs a electron from any molecule in its vicinity. It does this because electrons like to exist in pairs. When it grabs an electron from another molecule, it damages the other molecule.Gerontological Nursing, Second Edition Patricia A. TabloskiCopyright 2010 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

Free Radical Theory Some of the molecules that may be damaged by free radicals are fats, proteins, and DNA (both in the nucleus and in mitochondria). If membrane fats are attacked, then you get the breakdown of the cell membrane. If it is a red blood cell membrane, you get hemolysis. If proteins are attacked, you get the breakdown of proteins, which may result in the loss of biological function and the accumulation of catastrophic compounds. If DNA is attacked, you will get a mutation that may cause aging or cancer.Gerontological Nursing,

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