Question

The tissue in the human body (soft and hard) has unique structural and mechanical properties that allow it to carry out its different amazing roles. Select two of these biomechanical properties. Pick any tissue of your choosing and respond to the following questions

1. Define these two biomechanical properties

2. What structural/anatomical features result in these properties in your selected tissue

3. What is their value added from a functional perspective to the musculoskeletal system?

4. How would you test/quantify these properties?

5. What is the effect of immobilization/lack of activity on these properties?

Answer 1

1. Biomechanical properties can be defined as the strength, elasticity, flexibility, hardness, fatigue limit, etc. of any tissue of the body. Let us discuss the biomechanical properties of the skin.

The skin is the outermost covering of our body and acts as a barrier between the outer environment and the inner environment and organs of the body. It conforms to the body that it covers. Two biomechanical properties of skin are -

a] It acts as a physical barrier preventing external agents like microbes from entering the body.

b] It is elastic and can stretch.

2. The skin is primarily made of epidermal cells, and collagen and elastin fibers with blood supply and innervations from the nervous system. The outermost layer of the skin is made up of dermal cells which are continuously sloughed off and replaced by fresh cells. The main structural/anatomical factors which give the unique biomechanical properties to the skin are its dermis, collagen, and elastin elements which not only make it stretchable but also make it act as a physical barrier between the inner body and outer environments.

3. The musculoskeletal system is made up of the skeleton and the muscles covering the bones. The skeletal muscles and the bone joints work together to enable the body to move. In most parts of the body, the bones are covered by muscles which give the body shape. The skin covers the muscles and gives it protection.

4. To show that the skin acts as a physical barrier, one can pour water or any liquid over a part of the body. The liquid will flow off and is not able to enter the body through the skin. Oils and ointments are absorbed by the skin but that too very slowly. The skin also prevents the entry of several microbes into the body.

When we bend or stretch a part of the body, it is not only the muscles that contract and relax. The skin also expands and relaxes to enable movement. When a person gains weight, the skin also stretches to cover the increased body area.

5. There will not be much effect of immobilization or lack of activity on the properties of skin, their acting as physical barriers or their ability to stretch. However, continued pressure on any area of the skin for a very long time, say months, might cause sores. This is seen in people who are bedridden for a long time. They develop bedsores due to immobility and continuous pressure on the skin and muscles.