Senescence & the Biology of Aging

Lesson Transcript
Instructor: Natalie Boyd

Natalie is a teacher and holds an MA in English Education and is in progress on her PhD in psychology.

As people grow older, their bodies start to show signs of aging. In this lesson, we'll examine biological aging, also called senescence, including what it is, how it affects older adults, and what factors can affect how people age.


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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  • 0:02 Aging
  • 0:57 Senescence
  • 2:36 Environmental Factors
  • 4:40 Lesson Summary
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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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