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Senescence and Aging - What is Senescence?

What is Senescence?

We define senescence as the biological process of aging or the breakdown of the physical body while growing older. It doesn't happen the same way for everyone, though there are some critical characteristics of senescence that are common to nearly everyone. Two of these critical characteristics are related to environmental factors and cell processes.

Multiple factors account for the differences in how people age, one of which is genetic. Other factors are environmental factors such as nutrition, stress, and exercise. Stress speeds up senescence.

When does senescence begin?

Since senescence is the process of growing older, it begins in a person's twenties, immediately after they reach the peak of their physical strength and stop growing. After this physical peak, the person continues to age throughout their life but typically doesn't see many of the effects of aging until late adulthood. A person is considered to enter the late adulthood phase of life when they reach the age of 65. At this stage of life, many of the symptoms and effects of senescence start to show more. However, aging happens differently for everyone.

There are many scientific theories pertaining to aging, with an abundance of scientific research on the topic continuously being conducted. To define senescence scientifically, senescence research was started during the 1960s by Lenard Hayflick and Paul Moorhead. Through their research, they discovered that normal human fibroblast, in culture, can reach a maximum of 50 cell population doublings before becoming senescent.

The scientific process of senescence leads to many of the physical characteristics of aging.

Aging

Harriet is in her 70s, and she's noticed that things are different from the way they used to be. Her skin is wrinkled, her eyesight isn't as good as it once was, and her joints ache more now than they did when she was younger. She's also just not as fit; things she used to do, like climb a flight of stairs or run down the street, seem harder to accomplish now.

Harriet is in late adulthood, or the time of life after age 65. There are many exciting things about aging, including the fact that most older adults have more free time to pursue their passions and that they often have more wisdom than they did when they were younger. But there are also some problems with aging, as Harriet is discovering. Let's look closer at the biological aspects of aging, called senescence, and what environmental factors can affect them.

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Characteristics of Aging

To define aging, we consider how the physical body is no longer growing but is instead breaking down. Common examples of aging in late adulthood, which 65 years old or more, are:

  • worsening eyesight
  • hearing loss
  • wrinkled skin
  • digestive tract issues, such as indigestion

Wrinkled skin is a comon example of aging.

senescent changes

Three primary theories are associated with the biological aging process.

  1. One theory claims that aging is related to an accumulation of age-related mutations, or cells that are no longer being repaired or dividing.
  2. However, the pleiotropic antagonism theory is associated with the late effects of specific genes.
  3. The third theory is based on survival research done on opossums. It suggests that if an environment poses few hazards to interfere with life expectancy, it will result in members who have mutations that slow down the aging process.

The science behind the theories for aging will be discussed later in the lesson.

Multiple environmental factors can affect senescence: stress, nutrition, substance abuse, and exercise. They can speed up or slow down the aging process by affecting the cells and cell processes within the body.

Enviormental Factor Explanation
Stress Emotional and physical stress can speed the aging process. When the body is under stress, it releases 'fight-or-flight hormones which can cause a breakdown in cells and speed up the process of aging.
Nutrition A person's diet can affect how they age. For example, fruits and vegetables are high in antioxidants and can slow the aging process, but highly processed foods can speed it up.
Substance abuse Tobacco, alcohol, and other drugs can speed up the aging process.
Exercise Moderate exercise can slow down the aging process, while making a person look and feel better.

Everyone ages differently.

what is senescence

Senescence

As we've seen, Harriet is experiencing differences in her body due to aging. As she moves on in life, her age is impacting her physical being. For example, her eyesight isn't as good as it once was, and her skin is very wrinkled.

Senescence, which is also called biological aging, is the breakdown of the physical body. Think about Harriet's skin: When she was young, the cells in her skin were healthy and kept the skin smooth and wrinkle-free. But as she's aged, her skin cells have deteriorated and wrinkles have formed. The older she gets, the more this senescence occurs and the more wrinkles she'll have.

There are some common examples of senescence that most people experience as they age. For example, wrinkles are a very normal part of getting older, as is worsening eyesight and hearing. These are a part of the normal senescence that is happening in a person's body. At the same time, though, senescence doesn't happen exactly the same way in everyone. Harriet's friend Greta doesn't have the same symptoms as Harriet. For example, though Harriet struggles with joint pain, Greta is just as spry and pain-free as she was when she was younger.

But Greta has issues with her digestive tract that she's never had before. She used to be able to eat all sorts of spicy food, but now it really gives her indigestion. Harriet, though, almost never has a problem with indigestion. So, even though there are some common aspects of senescence that they are both experiencing, they are also different in the way that they are aging.

Environmental Factors

What can account for the differences in the way people age? Some of it is genetic. For example, Harriet's parents both had arthritis, and it's likely that Harriet's joint pain is arthritis-related. But environmental factors can also play a role in senescence. There are many, many things in the world around us that can affect how we age. Some of the more common ones are:

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Video Transcript

Aging

Harriet is in her 70s, and she's noticed that things are different from the way they used to be. Her skin is wrinkled, her eyesight isn't as good as it once was, and her joints ache more now than they did when she was younger. She's also just not as fit; things she used to do, like climb a flight of stairs or run down the street, seem harder to accomplish now.

Harriet is in late adulthood, or the time of life after age 65. There are many exciting things about aging, including the fact that most older adults have more free time to pursue their passions and that they often have more wisdom than they did when they were younger. But there are also some problems with aging, as Harriet is discovering. Let's look closer at the biological aspects of aging, called senescence, and what environmental factors can affect them.

Senescence

As we've seen, Harriet is experiencing differences in her body due to aging. As she moves on in life, her age is impacting her physical being. For example, her eyesight isn't as good as it once was, and her skin is very wrinkled.

Senescence, which is also called biological aging, is the breakdown of the physical body. Think about Harriet's skin: When she was young, the cells in her skin were healthy and kept the skin smooth and wrinkle-free. But as she's aged, her skin cells have deteriorated and wrinkles have formed. The older she gets, the more this senescence occurs and the more wrinkles she'll have.

There are some common examples of senescence that most people experience as they age. For example, wrinkles are a very normal part of getting older, as is worsening eyesight and hearing. These are a part of the normal senescence that is happening in a person's body. At the same time, though, senescence doesn't happen exactly the same way in everyone. Harriet's friend Greta doesn't have the same symptoms as Harriet. For example, though Harriet struggles with joint pain, Greta is just as spry and pain-free as she was when she was younger.

But Greta has issues with her digestive tract that she's never had before. She used to be able to eat all sorts of spicy food, but now it really gives her indigestion. Harriet, though, almost never has a problem with indigestion. So, even though there are some common aspects of senescence that they are both experiencing, they are also different in the way that they are aging.

Environmental Factors

What can account for the differences in the way people age? Some of it is genetic. For example, Harriet's parents both had arthritis, and it's likely that Harriet's joint pain is arthritis-related. But environmental factors can also play a role in senescence. There are many, many things in the world around us that can affect how we age. Some of the more common ones are:

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Frequently Asked Questions

What affects senescence?

There are a variety of things that affect senescence. They include genetic and environmental factors of stress, nutrition, substance abuse, and exercise.

What is another name for senescence?

Another name for senescence is aging. Senescence is the biological process of aging or the breakdown of the body as a person grows older.

What happens during senescence?

During senescence, cells stop dividing. The cells become senescent cells and build up in the body over the lifetime of mammals. While these senescent cells aid in a variety of biological factors, they also contribute to aging. When exposed to specific tissues and hormones, they can turn into cancer cells.

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