The Main Functions of the Skin, Its Structure and the Relationship Between the Skin, Circulatory and Nervous System

i. A labelled diagram of the skin and a description of it’s structure and function, including all key parts.
Skin Structure
The skin is the largest organ of the body. It has three main layers, the epidermis, the dermis and the subcutaneous layer (fat layer).

The Epidermis
The epidermis is a thin, tough, and elastic outer layer of the skin that is continually being regenerated. It includes the following:

Keratinocytes - the main cells of the epidermis and originate from cells in the deepest layer of the epidermis called the base layer. New Keratinocytes cells continually move up towards the surface of the epidermis. As they reach the skin surface they gradually die and are replaced by newer cells pushed up from below.

Corneocytes – the outermost portion of the epidermis is relatively waterproof and, when undamaged, prevents most bacteria, viruses, and other foreign substances from entering the body. The epidermis also protects the internal organs, muscles, nerves, and blood vessels against trauma. In certain areas of the body that requires greater protection the outer keratin layer of the epidermis is much thicker.

Melanocytes – these cells are scattered throughout the basal layer of the epidermis and produce the pigment melanin, one of the main contributors to skin color and protection against UV radiation by filtering out ultraviolet radiation from sunlight.
Langerhans – these cells are part of the skin's immune system with responsibility for detecting foreign substances and defending the body against infection. They also play a role in the development of skin allergies.

The Dermis
The dermis, the skin's next layer is a thick layer of fibrous and elastic tissue that gives the skin its flexibility and strength. It includes the following:

The nerve endings sense pain, touch, pressure, and temperature. Some areas of the skin contain more nerve endings than others. Fingertips and toes contain many nerves and are extremely sensitive to...