The time needed for a would to heal is related to the type of tissue injured and the amount of tissue that needs to be "reconstructed". Cell division rate is a factor too.

Healing is a complex process that involves multiple stages.

1. The body has to limit the damage that can result from the injury. So it tries to stop the bleeding and then a local inflammatory process is triggered. This inflammation will:

• stop pathogens from entering the systemic circulation
• "clean" the injured tissue by removing dead cells

2. In order to recreate the tissue, there is the need for blood which will deliver nutrients and other factors. So, fibroblasts and endothelial cells migrate in the wounded area and form a temporary tissue with new blood vessels which is called granulation tissue.

3. The granulation tissue allows the formation of the definitive tissue. This is the remodelling phase. Depending on the wound, the tissue that grows can be the same as the original one or a fibrous scar tissue.

Looking at the time required by these steps:

1. should be the fastest as it relies on blood cells and factors that are already present in blood. Also the would itself will stimulate the local production of some cells/factors involved (inflammatory factors, vasodilator, vasoconstrictor factors).

2. and 3. depend on cell division duration, extracellular matrix formation and vascularization. Cell division time can be slowed down by the lack of required nutrients/substances. While the granulation tissue forms in almost constant time no matter the injury, the final tissue depends on what type it will be. One simple example is bone tissue versus skin.

References & Links:

• Wound healing on Wikipedia
• John Miller: http://physioworks.com.au/treatments-1/what-are-the-phases-of-a-soft-tissue-injury

The time needed for a wound to heal is related to the type of tissue injured and the amount of tissue that needs to be 'reconstructed.' Cell division rates are also a factor.

Healing is a complex process that involves multiple stages.

1. The body has to limit the damage that can result from an injury. So, first it tries to stop the bleeding and then a local inflammatory process is triggered. This inflammation will:

• stop pathogens from entering the systemic circulation
• 'clean' the injured tissue by removing dead cells

2. In order to recreate the tissue, there is the need for blood which will deliver nutrients and other factors. So, fibroblasts and endothelial cells migrate in the wounded area and form temporary tissue and new blood vessels; the new tissue is called granulation tissue.

3. The granulation tissue allows for the formation of definitive tissue. This is the remodelling phase. Depending on the wound, the tissue that grows can either be the same as the original one or be fibrous scar tissue.

Looking at the time required by each of these steps:

1. should be the fastest as it relies on blood cells and factors that are already present in blood. Also, the wound itself will stimulate the local production of some cells/factors involved (inflammatory factors, vasodilator, vasoconstrictor factors.)

2. and 3. depend on the duration of cell-division processes, extracellular matrix formation, and vascularization. Cell division time can be slowed down by a lack of required nutrients and/or substances. While the granulation tissue forms in almost constant time no matter the injury, the final tissue depends on what type it will be. One simple example is bone tissue versus skin.

References & Links:

• Wound healing on Wikipedia
• John Miller: http://physioworks.com.au/treatments-1/what-are-the-phases-of-a-soft-tissue-injury