The Biology of Shaving, Part 1 of 4

1.  Skin

Your skin is the body’s largest organ. It functions as the interface between your internal structure and the external world – both highly complex environments.

The skin is organized into three main layers, the epidermis, the dermis,  and the hypodermis. each comprised of specialized cells. The epidermis serves a barrier function, preventing water and fluid loss, heat loss, and invasion of microbes and toxins. The epidermis is made up of specialized cells called keratinocytes. In the uppermost layer of the epidermis, the cells are encased in a protein and lipid matrix. It is this structure that provides the barrier function of skin. In the lower layers of the epidermis the keratinocyte cells stay metabolically active, altering their structures as necessary to support the upper layer.

The dermis is the middle layer of skin and consists mainly of connective tissue held together by collagen and elastin. Collagen is a structural protein that serves as the main component of connective tissue. It is the most abundant protein in the body, and among many other functions helps with blood clotting. Collagen in the dermis is composed of densely packed fibers and is like a glue that holds things together. (in fact the word comes from the Greek “Kolla” meaning glue, and the French “gene” meaning producing.) Elastin is also a protein and serves as a key component in connective tissue. It is highly elastic, and helps the skin resume its shape after stretching or contracting. (The scientists weren’t so clever in naming elastin.) The main function of the dermis is to provide both physical and nutritional support to the epidermis. The connective tissue holds together a mash of various glands, blood vessels, nerves, receptors, hair follicles, muscles, and specialized cells to provide support to the epidermis.

There is a third layer of skin called the hypodermis, which is composed mainly of fat cells, connective tissue, sweat glands, nerve cells, blood vessels, and fibroblasts. Fibroblasts are extremely versatile cells that function throughout the body, in organs, tissue, the lungs, and skin. In the body, fibroblasts play a vital role in the immune system, build matrix proteins, determine cell types and functions, and build molecules and enzymes. In the hypodermis, fibroblasts build the vital collagen used in the dermis.

The skin protects the body from foreign bacteria, viruses, invasive microorganisms, ultraviolet radiation, allergens and other irritants, regulates temperature, and responds to stimuli.  When it is damaged, that protection is compromised, and skin cells must begin the process of healing. For that they need nutrients.