The Skin The Great Protector

When it comes to studying anatomy and physiology, one of the most fascinating revelations is the skin. As the the largest organ in the body it has the ability to protect, manufacture, thermoregulate, absorb, secrete and eliminate. It is a super organ, in fact.

Its primary function is to protect and the techniques it uses are impressive. Whilst it is tough enough to keep microbes, bacteria, toxic substances and infections out, it is flexible enough to keep water and vital nutrients that the body needs in.

The skin is made up of three distinct layers: epidermis, dermis and subcutaneous layer.

Each one has unique defence systems to protect our bodies.

The Epidermis

The epidermis is the outermost layer and, first and foremost, is an effective, physical barrier from foreign bodies. It is home to Langerhans Cells (LCs). These are like soldiers on the front line of defence and are not to be confused with the Islets of Langerhans, found in the pancreas. (However, they were both discovered by Paul Langerhans, a German pathologist, hence their names).

LCs sound the alarm that the body is under attack by dispatching T cells and B cells. These immune cells hunt down and capture any pathogens, sending information about them back to the LCs. Depending on the level of danger, the LCs will then set up a group of inflammatory cells to fight infection. Otherwise known as an allergic reaction.

Also present in the epidermis are melanocytes. These are highly specialised cells that manufacture melanin, a natural pigment. Melanin is what gives colour to our skin, hair and eyes. The more melanin, the darker the colour. This pigment is produced in response to sun exposure (the tanning effect on the skin) and has the ability to absorb UV light, thus preventing damage.

The Dermis

This is the thickest layer of skin and as it performs so many roles, it is often considered the most vital:

Sweat glands act to regulate body temperature, preventing overheating

Toxins are removed via the network of blood vessels

Bacteria-eating phagocytes provide extra protection from any toxins that have penetrated the epidermis

Sebaceous glands produce sebum, a bactericidal oil

Protection from the cold is provided by the clever system of minuscule muscles, arrector pili, attached to the hair follicles

All of the above are surrounded by three types of connective tissue - collagen, elastin and reticular fibres. These form a strong guard of physical protection.

Finally, the Subcutaneous Layer (or Hypodermis)

 This layer is predominantly made up of adipose tissue or fat. It acts as cushioning to absorb shocks and also as insulation to prevent heat loss.

With all the above in mind, it is fair to say that our skin works hard to protect us.

A Great Protector!

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