Structural System

What I Do In Your Body...

We don't pay much attention to our structural system, until something

goes wrong. Most of us know that our bones and muscles are part of the structural

system, but it also includes skin, membranes and connective tissues.

The SKIN, also called the Integumentary System, is the external covering of our

body but also covers the appendages of the skin such as hair, your nails and even the

glands of the skin. The skin's function is to protect us and prevent dehydration,

regulate temperature and help in the process of elimination. In other words, keep

out the stuff OUTSIDE and keep in the stuff INSIDE! Part of that job is to keep

the millions of living organisms that live on our skin where they belong, outside.

All of these organisms have a purpose, some even help us fight infections! You could

call your skin the "Keeper of the Door," because it can let in things like water and let out heat.

Getting specific, our skin is one of a group of sheet-like structures called

Membranes. There are two major categories of membranes:

Epithelial Membranes

Connective Tissue Membranes

These membranes cover and protect your body surface, they line body cavities and cover the inner surfaces of the hollow organs like your digestive tract, parts of your reproductive system and even your respiratory passages.

If you laid your skin out flat, it would probably measure between twelve and twenty square feet; it makes up about 16% of our body weight and has three layers. In the middle layer is where you'll find the skin's blood vessels and sweat glands. This second layer is called the dermis. This is where injured tissue is repaired. The dermis layer helps the skin do a very important job: temperature control. In cold weather, blood flow slows down and hairs are pulled erect to trap a layer of air next to the skin to provide the extra insulation needed to keep body heat trapped. When it's hot, sweat is secreted from the sweat glands and that moisture evaporates from the surface of the skin, taking excess heat from the body. The outer layer, epidermis, is the thinnest layer of skin and this is where your nerve endings reside. They are so sensitive that you can feel the gentlest touch.

The subcutis is the bottom layer of skin and this layer is made up mostly of lipids, or fats that provide a cushion for bones and other things inside. This is also a layer of insulation.

The appendages of the skin include your hair. Our bodies are covered with millions and millions of hairs. Follicles are the structures that are required for our hair to grow and fortunately we have what we need by the time we are born. Although you may think that hair is simple and even boring; there's a lot going on around each of the hairs on your body. Your hair begins its growth in the follicle as a small, cap-shaped cluster of cells called the hair papilla which is located at the base of the follicle. These cells are nourished by a dermal blood vessel. As long as these cells are alive, you'll grow new hair to replace the hair that is lost.

And speaking of hair, there's an old wives tale that says the if you shave or cut your hair more often it will make the hair grow faster and become coarser. It's not true because none of these external things have any effect on the epithelial cells that form your hairs. They are embedded too far down in the dermis.