what is aging? what are its signs and symptoms? why do people age?

1. Aging

2. Ageing or aging is the process of becoming older. Aging is essentially an accident, an accumulation
of damage and wear and tear to the body which eventually leads to death.
Aging takes place in a cell, an organ, or the total organism with the passage of time. It is a process
that goes on over the entire adult life span of any living thing.
Gerontology, the study of the aging process, is devoted to the understanding and control of all
factors contributing to the finitude of individual life.
The term refers especially to humans, many other animals, and fungi. In the broader sense, ageing
can refer to single cells within an organism which have ceased dividing (cellular senescence) or to
the population of a species (population ageing).
In humans, ageing represents the accumulation of changes in a human being over time and can
encompass physical, psychological, and social changes. Reaction time, for example, may slow with
age, while knowledge of world events and wisdom may expand. Ageing is among the greatest
known risk factors for most human diseases.

3. Effects:
A number of characteristic ageing symptoms are experienced by a majority or by a significant proportion
of humans during their lifetimes.
 Teenagers lose the young child's ability to hear high-frequency sounds above 20 kHz.
 Wrinkles develop mainly due to photo ageing, particularly affecting sun-exposed areas (face).
 After peaking in the mid-20s, female fertility declines.
 Muscles have reduced capacity of responding to exercise or injury and loss of muscle mass and
strength (sarcopenia) is common.
 Hand strength and mobility are decreased during the aging process. These things include, "hand and
finger strength and ability to control submaximal pinch force and maintain a steady precision pinch
posture, manual speed, and hand sensation"
 People over 35 years of age are at increasing risk for losing strength in the ciliary muscle which leads
to difficulty focusing on close objects.
 Around age 50, hair turns grey. Pattern hair loss by the age of 50 affects about 30–50% of males and a
quarter of females.
 Menopause typically occurs between 44 and 58 years of age.

4. Biological basis of Aging:
The factors proposed to influence biological ageing fall into two main categories
programmed and damage-related. Programmed factors follow a biological timetable, perhaps one that might
be a continuation of the one that regulates childhood growth and development. This regulation would depend on
changes in gene expression that affect the systems responsible for maintenance, repair and defense responses.
Damage-related factors include internal and environmental assaults to living organisms that induce cumulative
damage at various levels.
Nine metabolic "hallmarks" of ageing in various organisms but especially mammals are following:
 Genomic instability (mutations accumulated in nuclear DNA, in mt DNA, and in the nuclear lamina)
 Telomere attrition (the authors note that artificial telomerase confers non-cancerous immortality to otherwise
mortal cells)
 Epigenetic alterations (including DNA methylation patterns, post-translational modification of histones, and
chromatin remodeling)
 Loss of proteostasis (protein folding and proteolysis)
 Mitochondrial dysfunction.
 Cellular senescence.
 Stem cell exhaustion.

5. How Cells Age:
Cells are the basic building blocks of tissues. All cells experience changes with aging. They become larger and
are less able to divide and multiply. Among other changes, there is an increase in pigments and fatty substances
inside the cell (lipids). Many cells lose their ability to function, or they begin to function abnormally. As aging
continues, waste products build up in tissue. A fatty brown pigment called lipofuscin collects in many tissues, as
do other fatty substances.
Connective tissue changes, becoming more stiff. This makes the organs, blood vessels, and airways more rigid.
Cell membranes change, so many tissues have more trouble getting oxygen and nutrients, and removing carbon
dioxide and other wastes.
Many tissues lose mass. This process is called atrophy. Some tissues become lumpy (nodular) or more rigid.
Because of cell and tissue changes, your organs also change as you age. Aging organs slowly lose function.

6. Causes of Aging:
1. Collagen breakdown
Represents 75% of the skin’s dry weight. The quantity and the quality play a major role in the skin’s appearance.
Slowing down the breakdown and degradation of collagen fibers is vital to skin youth.
2. Photo Defense
Repeated exposure to ultraviolet light (UV radiation) from the sun accounts for almost 90% of symptoms of
premature skin ageing, skin damage and skin cancer. The sun is carcinogenic and harmful to the skin. Just a few
minutes of sun exposure each day over the years can cause noticeable changes to the skin.
3. Oxidation
This process starts with free radicals which are highly reactive small molecules that can damage virtually any
molecule in the body, including the important cellular structures found in the body’s largest organ – the skin.
4. Inflammation
This is the skin’s first line of defense against foreign invaders such as bacteria and viruses. Inflammation also
initiates the tissue healing process and limits the damage to skin cells caused by everyday chemicals and
pollutants.
5. Glycation
Sad to say sugar does make you age faster. Glycation causes the skins proteins (like collagen and elastin) to lose
their ability to function normally and is now well recognized and heavily implicated in accelerated skin ageing.

7. Levels of Aging:
In other words, aging is the impact of time on the human body, and it occurs on multiple levels:
 Cellular aging: Cells age based on the number of times they have replicated. A cell can replicate about 50
times before the genetic material is no longer able to be copied accurately, which is due to shortened
telomeres. The more damage done to cells by free radicals and other factors, the more cells need to
replicate.
 Hormonal aging: Hormones play a huge factor in aging, especially during childhood growth and
adolescent maturity. Hormone levels fluctuate through life. Puberty brings acne and larger pores. As we get
older, hormonal changes lead to dry skin and menopause.
 Accumulated damage: Accumulated damage is all external. Exposure to toxins, the sun, harmful foods,
pollution, and smoke take a toll on the body. Over time, these external factors can lead to tissue damage
and the body falls behind in its ability to maintain and repair cells, tissues, and organs.
 Metabolic aging: As you go about your day, your cells are constantly turning food into energy, which
produces byproducts that can be harmful. The process of metabolizing and creating energy results in
damage to the body over time. Some believe that slowing down the metabolic process through practices
such as calorie restriction may slow aging in humans.

8. Genetics of Aging:
The genetic theory of aging centers on telomeres, which are repeated segments of DNA (deoxyribonucleic acid)
occurring at the ends of chromosomes. The number of repeats in a telomere determines the maximum life span
of a cell, since each time a cell divides, multiple repeats are lost. Once telomeres have been reduced to a certain
size, the cell reaches a crisis point and is prevented from dividing further. As a consequence, the cell dies.
Research has shown that telomeres are vulnerable to genetic factors that alter an organism’s rate of aging. In
humans, variations in a gene known as TERC (telomerase RNA [ribonucleic acid] component), which encodes
an RNA segment of an enzyme known as telomerase, have been associated with reduced telomere length and
an increased rate of biological aging. Telomerase normally functions to prevent the over shortening of
telomeres, but in the presence of TERC mutations the enzyme’s activity is altered. TERC also appears to
influence the telomere length that individuals possess from the time of birth.
Genetic Theory of Aging
The genetic theory of aging states that lifespan is largely determined by the genes we inherit. According to the
theory, our longevity is primarily determined at the moment of conception and is largely reliant on our parents
and their genes.
The basis behind this theory is that segments of DNA that occur at the end of chromosomes, called telomeres,
determine the maximum lifespan of a cell. Telomeres are pieces of "junk" DNA at the end of chromosomes
which become shorter every time a cell divides.

9. Slowing Down Aging
 Eat well. Within the past few decades, processed foods have become an increasingly larger part of our diets.
Added sugar, salt, and fat are all wreaking havoc on our bodies, leading to a multitude of serious health
issues, including cardiovascular disease and hypertension. Do yourself a favor and eat well. As a general
rule of thumb, if you have to open it to eat it, you shouldn't be eating it. Read labels. Cut out sugary drinks
and white starches, and incorporate more fruits, vegetables, fiber, and lean proteins.
 Don't smoke. If you're a smoker, you've likely struggled with quitting, but don't give up. Quitting smoking
improves circulation and blood pressure, and drastically reduces your risk of developing cancer.
 Exercise. You might not be meeting the recommended 30 minutes of activity a day, 5 days a week, but the
good news is that even just 15 minutes of moderate activity a day can improve longevity. Walk the dog, ride
a bike or take a fitness class. Any activity is better than none at all.
 Socialize. Socialization keeps us young and does wonders for longevity. Maintain good, healthy
relationships with others. Stay connected to the ones you love and make it a point to meet new people.
 Get sleep. Ignore the saying "you'll sleep when you're dead." You need sleep, regardless of the relationship
you have with it. Get a good night of sleep every night and you'll reduce your risk of heart disease and
lower your stress levels.
 Don't stress. Stress, anger and holding onto grudges can be very damaging.