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Cellular Adaptation and Its Types

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Cells can change according to stimuli and surrounding changes. This article highlights such adaptation mechanisms of cells. Read on to know more.

Medically reviewed by

Dr. Nagaraj

Published At October 28, 2022
Reviewed AtMay 10, 2023

Introduction:

According to the surroundings, cells can change their structure and function. This helps them maintain their function and survive. The cells adapt to their surroundings. These changes occur in response to stimuli. Removal of stimulus can reverse these changes. The state of the cell is different, but the function remains the same. These changes can be responses to changes in blood or nutrient supply, prolonged irritation, or an increase in need.

What Is Cellular Adaptation?

Cells can transform to adapt to their surroundings. This helps them function better.

What Are the Types of Cellular Adaptation?

1. Proliferation:

Proliferation is an increased number of cells due to rapid division. Our body has three types of cells. These cells have different rates of turnover. Following are the types of cells in our body.

  • Labile Tissue: They can divide and renew at an increased rate. Their life is of short duration. They are derived from stem cells. The lining of the gastrointestinal tract, skin, and respiratory tract have labile cells. They can regenerate as and when needed. A skin injury can heal itself due to the high turnover rate of skin cells.
  • Stable Tissue: These cells have a low rate of turnover. They divide and die at a slower rate. However, the rate increases if the tissue suffers any damage. This facilitates complete recovery of the organ. Liver and kidney cells have stable cells. The liver and kidney cells can regenerate post-surgery.
  • Permanent Tissue: These cells have little or absolutely no turnover. Heart and brain cells cannot replicate.

2. Regeneration:

Regeneration is the natural process of replacement.

  • Complete Regeneration: As the name suggests, complete repair of damaged tissue takes place. The repair is adequate in function as well as structure. This takes place only in labile and stable cells. When skin healing occurs without scarring, it is called complete regeneration.
  • Incomplete Regeneration: The repair of tissue is incomplete and inadequate in function. The quality of tissue is compromised. This takes place in permanent and stable tissue. When skin healing occurs with scarring, it is called incomplete regeneration.

3. Anaplasia:

Anaplasia is when cells lose the ability to differentiate into mature cells. This is seen in cancerous cell division.

4. Hypertrophy:

Hypertrophy is an increase in cellular size and function; however, the number of cells remains the same. This leads to an increase in the size of the organ also.

  • Physiologic Hypertrophy: This mainly occurs due to hormonal stimulus or the presence of growth factors. One can correlate hypertrophy with the growth of muscle tissue after a vigorous workout. Another classic example is an expansion of uterine tissue during pregnancy.

  • Pathologic Hypertrophy: This occurs when the increase in cellular activity is uncontrolled. Hypertrophy has a limited rate of increase in cell size. It is not an unlimited phenomenon. If the stimuli are continuous, it might lead to cell death. This can be explained when blood pressure is high; there is undue pressure on the heart muscle. Muscles have to work extra to pump blood. This leads to the thickening of the left ventricle (lower chamber of the heart). This condition is also termed left ventricular hypertrophy.

5. Hyperplasia:

Hyperplasia means an increase in the number of cells. This occurs due to stimuli. This is characteristic of only cells that can divide. This also leads to an increase in the size of organs.

  • Physiologic Hyperplasia: When it takes place due to natural hormones, as seen concerning the growth of mammary glands during puberty.

  • Compensatory Hyperplasia: It is the process when cell division or an increase in the number of cells takes place to repair any damaged part of the organ. This is seen in cases of liver or kidney resection after surgeries when the resected part grows back.

  • Pathologic Hyperplasia: It occurs when there is an excessive or abnormal hormonal response. This response causes an increase in growth factors. This leads to increased cellular proliferation. If this does not stop, there is an increased risk of cancer. This is seen in cases when increased estrogen production causes the overgrowth of endometrial tissue. This increases the risk of cysts and tumors.

6. Atrophy:

Atrophy is the reduction in the size and number of cells. This also reduces the metabolic activity of the cell. When there is increased protein breakdown and decreased production, atrophy is seen. Autophagy is a part of atrophy in which the cell eats its own contents. It is a self-destructive process. It reduces the blood supply. This type of cell response is irreversible. If this process continues, it can cause organ shrinkage.

  • Physiological Atrophy: It is seen when the cell size decreases naturally after the removal of the stimulus. This is seen when uterine tissue goes back to average size after childbirth.

  • Pathologic Atrophy: This occurs when cells reduce in size due to a decrease or absence in activity or function, like the loss of muscle mass seen on discontinuation of a physical workout. When estrogen levels decrease during menopause, vaginal atrophy occurs.

7. Metaplasia:

Metaplasia is a change in cell type due to long-term irritation or stress. This causes a decrease in functional activity. This changes the cells and makes them resistant to adverse environments. Stimuli can sometimes lead to malignant changes or cause regressive changes.

  • Physiological Metaplasia: It is seen in cervical ectopy.

  • Pathologic Metaplasia: It is seen in Barrett's esophagus when constant acid reflux can lead to adenocarcinoma. Another classic example is seen with vitamin A deficiency; metaplasia of corneal squamous cells takes place called the Bitot’s spot. Long-term smoking can change the epithelium of the respiratory tract from ciliated columnar to stratified squamous epithelium.

8. Dysplasia:

Cells are of different sizes and shapes due to irregular growth patterns. This is a false adaptation of the cells. Mild to moderate changes do not alter the underlying epithelium. Severe dysplasia can be precancerous in nature. Stimuli change the differentiation mechanics of the cells. They resemble the cells of the surrounding structure.

  • Congenital Dysplasia: When cell growth is altered during development.

  • Acquired Dysplasia: It is acquired when cell growth is altered as a response to metaplasia or hyperplasia.

Conclusion

Cells undergo changes to adapt to their surroundings. These cellular adaptations are reversible. The cell returns to its normal state when the stimuli are taken away. However, the prolonged presence of stimuli can impact the function of cells and lead to cell injury.

Frequently Asked Questions

1.

What Does Cellular Adaptation Mean?

Cellular adaptation suggests changes a cell makes in response to unfavorable environmental changes or various types of stimuli. These changes may be physiological or pathological. The cellular adaptation is reversible and allows the cells to survive and function adequately.

2.

How Does Cellular Adaptation Help?

Cellular adaptation allows a cell to cope with changes in its surroundings. As a result, the cells undergo structural and functional changes to function better and survive in the new environment.

3.

How Do Cells Respond to Stress?

Exposure to environmental stimuli triggers the activation of stress sensors within the cells. Depending on the severity and duration of stress encountered, the cells either re-establish their regulatory process to the former state or adopt an altered state to survive in the new environment. These may include hyperplasia, metaplasia, hypertrophy, and atrophy.

4.

What Is the Process of Adaptation?

To cope with their environment, cells undergo reversible structural and functional changes. These processes may consist of increasing the cellular size (hypertrophy), increasing the number (hyperplasia), decreasing the cell size (atrophy), or bringing a change in their phenotype (metaplasia).

5.

What Does Physical Adaptation Mean?

Physical adaptations refer to changes in an organism's physical characteristics to help it survive in a changing environment. It may involve structural changes made to a body part to adapt to the surrounding environment.

6.

What Are the Different Types of Adaptation?

Adaptation to the environment allows the organism to modify itself to its surroundings. It can be
- Structural Adaptation - Changes in the structure to better adapt to an environment, such as in desert plants and animals.
- Behavioral Adaptation - Changes in the organism's behavior to survive better, such as migratory birds flying to the west.
- Physiological Adaptation - A method of the brain that enables an organism to best survive in a setting, such as animals in cold areas having dense fur and short legs.
- Co-Adaptation - When two or more species are symbiotically linked together to survive and evolve.

7.

How Is Adaptation Important for Humans?

Humans adapt to the environment to survive and respond well to the changing environment. Adapting to the surroundings reduces their vulnerability to its impact. Adapting to the environment involves modifying in different ways to survive in different climatic conditions of the ecosystem, predators, and competition for food and space.

8.

Is DNA Involved in Adaptation?

Yes, adaptation to the environment can help the progeny to adapt better. Organisms with adaptations tend to live longer and reproduce more, passing the gene onto offspring through genetic means, increasing the presence of a particular gene in that species' gene pool.

9.

How Is Adaptation Beneficial?

The primary objective of adaptation is to protect current patterns of biodiversity. Adaptations help an organism survive and increase its ability to reproduce. Adapting to the environment helps one to have the flexibility to eat, learn from others, live in different environments, and benefit from any associated opportunities, where possible.

10.

How to Define Adaptation in Medicine?

Adaptation can be a good change in the function or constitution of an organ or part to adjust to a new condition. It can be an ongoing process for living organisms, the survival, reproduction, and functioning of a living organism.
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Dr. Nagaraj
Dr. Nagaraj

Diabetology

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cellular adaptationexcessive cell proliferationcell morphology
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