Collegedunia Team Content Curator
Content Curator
Hypertrophy and hyperplasia are biological processes involved in growth of tissue or organs. Although all tissues and organs of the human body are normally subject to the hormones or growth regulating factors, many are potentially capable of unlimited growth while others are not. Hypertrophy is essentially cell enlargement whereas hyperplasia is cell proliferation.
| Table of Content |
Key Takeaways: Hypertrophy; Hyperplasia; cell growth; Cell size, Cellular proliferation.
Hypertrophy
Hypertrophy is an increase in the size of cells (or tissues, organs) in response to a stimulus. Muscular hypertrophy in response to exercise is a typical example. Physical exercise stimulates skeletal and cardiac muscle fibers to increase in diameter and to accumulate more structural contractile proteins.
Hypertrophy
Types of Hypertrophy
- Hypertrophy can be a compensatory response to damaged or lost parenchymatous cells. For example, after a person has undergone myocardial disease, cardiac muscle cells are unable to undergo hyperplasia to replace the destroyed muscle fibres but the rest of the heart muscle cells enlarge (hypertrophy) in order to replace some of the functions of the lost myofibers.
- Hypertrophy can be adaptive and improve function. It is physiologic hypertrophy.
- Pathologic hypertrophy: Hypertrophy can be adaptive in certain situations but it can also lead to alteration in gene expression.
Also read:
Hyperplasia
Hyperplasia is an increase in the number of cells within a given tissue due to cellular proliferation. Hyperplasia refers to an increased number of cells, the cells appear normal in size, but can lead to an enlargement of an organ or tissue. Such proliferation occurs in response to a certain stimulus. Hyperplasia can be a pathological response to abnormal levels of growth factors or hormones, resulting in a number of disorders and dysfunctions.
Hyperplasia
Causes of Hyperplasia
There are numerous causes of hyperplasia, including:
- There is a demand for increased tissue in order to compensate for the cell loss (e.g., the skin or wound healing).
- Chronic inflammation.
- Abnormal levels of hormones and growth factors.
- Diseased tissue within the body.
Types of Hyperplasia
Given below are the types of hyperplasia:
- Physiologic Hyperplasia:
- Hormonal hyperplasia
- Compensatory hyperplasia
- Pathological Hyperplasia:
- Endometrial hyperplasia
- Benign prostatic hyperplasia
- Skin warts
Also Read:
Difference between Hypertrophy and Hyperplasia
| Hypertrophy | Hyperplasia | |
|---|---|---|
| Definition | It is an increase in the size of a cell resulting in enlargement of the organ or tissue without any change in the number of cells (increased size) | It is an increase in parenchymal cells numbers resulting in enlargement of organs and tissue. (Increased volume/mass) |
| Causes | Increased functional demand or by hormonal stimulation. | Causes- Increased in number of cells going from G0 (G Zero) phase of the cell cycle to undergo mitosis. |
| Types | Physiological– muscular hypertrophy is due to increased workload, growth of uterus during pregnancy. Pathological– change in gene expression | Physiological – hormonal hyperplasia; Pathological – inhibition of cancer inhibiting factors. |
| Mechanism | Result of increased production of cellular protein. | Result of growth factor, hormones driven proliferation of the mature cell. |
| Cells affected | This occurs in non-dividing cells. Permanent cell (such as cardiac muscle, skeletal muscle) | Occurs in dividing cells. Labile or stable cells. |
| Process | It is essentially cell enlargement. | It is essentially cell proliferation. |
| Location | In non-dividing cells | In dividing cells. |
Also read: DNA replication
Things to Remember
- Hyperplasia is different from hypertrophy. Hypertrophy is an increase in the size(enlargement) of cells, whereas in hyperplasia, it is an increase in the number(proliferation) of cells.
- Some of the body's most vitally essential organs like heart, brain, kidney, lung, etc lack the ability to make additional structural units in the adult.
- Some organs like glands, renewing tissues, etc have unlimited powers of regeneration because they never lose the capacity for hyperplasia.
- Sometimes hypertrophic organs lose the capability for hyperplasia.
Also Read:
Sample Questions
Ques. What is hypertrophy? Mention its types. (4 Marks)
Ans. Hypertrophy is an increase in the size of cells (or tissues, organs) in response to stimulus.
Types:
- Hypertrophy can be a compensatory response to damaged or lost parenchymatous cells. For example, following myocardial disease, cardiac muscle cells cannot undergo hyperplasia to replace destroyed muscle fibres but the rest of the heart muscle cells enlarge (hypertrophy) in order to make up for some of the function of the lost myofibers.
- Hypertrophy can be adaptive and improve function. It is physiologic hypertrophy.
- Pathologic hypertrophy: Hypertrophy can be adaptive in certain situations but it can also lead to alteration in gene expression.
Ques. Write about the four principles related to hypertrophy. (4 Marks)
Ans. To understand hypertrophy, Principles of Specificity, Overload, Adaptation, and Reversibility is useful:
1) The Principle of Specificity: Responses are specific to the stimuli.
2) The Principle of Overload: For a tissue to adapt to a response, it must be progressively stimulated.
3) The Principle of Adaptation: The cells, organs or body will adapt (or response) physiologically to the stimulus it gets.
4) The Principle of Reversibility: Any gains are progressively lost when stimulus is stopped
Ques. Define hyperplasia. And mention its causes. (4 marks)
Ans. Hyperplasia is an increase in the number of cells within a given tissue due to cellular proliferation. Hyperplasia refers to an increased number of cells, the cells appear normal in size, but can lead to an enlargement of an organ or tissue. Such proliferation occurs in response to a certain stimulus.
There are numerous causes of hyperplasia, including:
- demand for increased tissue to compensate for a loss of cells (e.g., the skin or wound healing)
- chronic inflammations
- abnormal levels of hormones and growth factors
- diseased tissue within the body
Ques. Write about hyperplasia in humans, its role and diseases associated with it. (3 marks)
Ans. In humans, to a certain extent hyperplasia is required on a regular basis, such as the replacement of skin cells on the epidermal layer. Hyperplasia is also required in the breasts of pregnant women for the growth of the milk glands in order to breastfeed the newborn.
The process of hyperplasia is also used (and misused) in various sports for the purpose of increasing the number of skeletal muscle cells to improve athletic performance.
Some of the more commonly known clinical forms of diseases related to hyperplasia:
- Benign prostatic hyperplasia,
- Cushing's disease
- Congenital adrenal hyperplasia
- Endometrial hyperplasia
- Hemi hyperplasia
Ques. Mention type of hypertrophy and hyperplasia. (4 marks)
Ans. Both hypertrophy and hyperplasia can be divided into many types. Typically, both can be divided into physiological and pathological categories.
Hypertrophy: It is an increase in the size of a cell resulting in enlargement of the organ or tissue without any change in the number of cells.
Physiological– muscular hypertrophy is due to increased workload, growth of uterus during pregnancy.
Pathological– change in gene expression.
Hyperplasia: It is an increase in parenchymal cell numbers resulting in enlargement of organ and tissue.
Physiological – hormonal hyperplasia;
Pathological – inhibition of cancer inhibiting factors.
Ques. Mention four differences between hypertrophy and hyperplasia. (4 marks)
Ans:
| Hypertrophy | Hyperplasia | |
|---|---|---|
| Mechanism | Result of increased production of cellular protein. | Result of growth factor, hormones driven proliferation of the mature cell. |
| Cells affected | This occurs in non-dividing cells. Permanent cell (such as cardiac muscle, skeletal muscle) | Occurs in dividing cells. Labile or stable cells. |
| Process | It is essentially cell enlargement. | It is essentially cell proliferation. |
| Location | In non-dividing cells | In dividing cells. |
What is the cell cycle? (3 marks)
Ans: Cell cycle is the series of events that take place in a cell that divides it into two daughter cells. Cell cycles involve DNA replication, partitioning of cytoplasm and other components into two daughter cells in a process called cell division.
In eukaryotes, cell cycle is divided into two main stages: interphase and the mitotic (M) phase (including mitosis and cytokinesis). During interphase, the cell grows, accumulating nutrients and replicating its DNA. During the mitotic phase, the replicated DNA, organelles, and cytoplasm separate and divide into two daughter cells.
Comments