Hypertrophy and Hyperplasia

Hypertrophy and Hyperplasia are terms that are often used in medical contexts. The difference between hypertrophy and hyperplasia mainly lies in the degree of cell proliferation. For example, a muscle can grow in size due to an increase in the size of individual cells (hypertrophy) or by increasing the number of cells within it (hyperplasia).

What is Hypertrophy?

Hypertrophy is the increased volume of muscle fibres through the enlargement of individual muscle cells. This can be caused by an increase in protein synthesis rate and occurs due to an increase in the activity of the myonuclei. For example, if a particular motor neuron incites a muscle cell to enlarge, this event will result in hypertrophy of that muscle cell. The muscles that are involved in a weight lifting exercise grow due to hypertrophy (due to an increase in protein synthesis rate).

What is Hyperplasia?

Hyperplasia is a different kind of response in cells to stress or damage. It occurs when undifferentiated, unspecialized cells begin to differentiate into specific types of tissue. This process can occur suddenly or it can be a more gradual change.

Difference Between Hypertrophy and Hyperplasia – What are the signs and symptoms?

The main difference between hypertrophy and hyperplasia lies in the degree of cell proliferation and growth which takes place.  This also depends on if the muscle has been developed for years or if it is a newly developed muscle at the same time as bone growth occurs. Some other key differences are:

1) Hypertrophy has a significant increase in the size of individual cells, whereas hyperplasia produces an increase in the number of cells.

2) Hypertrophy is due to the enlargement of pre-existing cells, while hyperplasia results from an increase in the number of cells.

3) It can take days for hypertrophy to occur since it requires time for damaged tissue to be replaced by new muscle fibres. In contrast, it only takes a few hours for hyperplasia to happen, like new tissue forms from scratch.

4) Hyperplasia may not be permanent if no further damage is inflicted. However, hypertrophy is permanent, even if the muscle does not sustain further damage.

5) The degree of hypertrophy can be easily identified by an increase in tissue size. In contrast, hyperplasia is not as easy to identify. This is because many of the underlining processes and reactions take place behind the scene, within cells and tissues.

6) Hyperplasia may also occur in areas of bone growth as new bone tissue forms at a wound site. For example, after a fracture has healed or during periods of increased bone density where new bone formation occurs due to the increase in osteoblasts (bone-forming cells). This can be seen as a hypertrophic response in the bone tissue. It is, therefore, possible for hyperplasia to occur in both muscle and bone tissues. The same mechanisms can be used by muscles and bones to grow in size.

7) Although hyperplasia can lead to an increase in serum creatine kinase (CK) levels, this is not the case when muscle cells undergo hypertrophy. In contrast, CK levels will rise if the injury site has been caused by a fracture.

8) Hyperplasia may help to explain why skeletal muscles are sometimes able to repair themselves without scarring or fibrosis after an injury has occurred.

Conclusion:

As you can see there are some significant similarities and differences between hypertrophy and hyperplasia.  Both processes typically result in increased cell size or an increase in the number of cells within a tissue. In some cases, they may also be two sides of the same coin due to their relationship with each other. For example, both processes can occur simultaneously when a tissue is injured or damaged as part of the healing process. It is important not to confuse hyperplasia with metaplasia, which is a completely different process.