Your skin is the largest organ of your body, made up of several different components, including water, protein, lipids, and different minerals and chemicals. Its job is crucial: to protect you from infections and other environmental assaults. The skin also contains nerves that sense cold, heat, pain, pressure, and touch.
Throughout your life, your skin will change constantly, for better or worse. In fact, your skin will renew itself approximately once a month. Proper skin care is essential to maintaining the health and vitality of this protective organ.
The skin is made up of layers. It consists of a thin outer layer (epidermis), a thicker middle layer (dermis), and the inner layer (subcutaneous tissue or hypodermis).
Epidermis: The Outer Layer of Skin
The outer layer of skin, the epidermis, is a translucent layer made of cells that function to protect us from the environment. The most superficial portion contains dead skin cells that are continually shed. The deepest portion contains basal cells that are responsible for skin renewal. Keratin, a protein made within the cells of the epidermis, protects the skin from harmful substances, such as chemical products and bacteria. The epidermis also contains cells that produce melanin, which gives skin its color.
The epidermis is responsible for the look and health of the skin and it holds a large amount of water. The younger the body, the more water there is in the skin. The capacity of the skin to retain water decreases with age, making the skin more vulnerable to dehydration.
Keratin is the strongest protein in your skin. It also gives hair and nails their strength.
Dermis: The Middle Layer
The dermis contains two types of fibers that lessen in supply with age: elastin, which gives skin its elasticity, and collagen, which provides strength. The dermis also contains blood and lymph vessels, hair follicles, sweat glands, and the sebaceous glands, which produce oil. Nerves in the dermis sense touch and pain.
Collagen is the most abundant protein in the skin. It makes up 75% of your skin. This is also your "fountain of youth," responsible for warding off wrinkles and fine lines. Over time, environmental factors and aging diminish your body's ability to produce collagen.
Elastin is found together with collagen and is responsible for giving structure to your skin and organs. As with collagen, elastin is affected by time and the elements. Diminished levels of this protein cause your skin to wrinkle and sag.
Hypodermis: The Fatty Layer
The subcutaneous tissue, or hypodermis, is mostly made up of fat. It lies between the dermis and muscles or bones and contains blood vessels that expand and contract to help keep your body at a constant temperature. The hypodermis also protects your vital inner organs. Reduction of tissue in this layer causes your skin to sag.
Sebaceous Glands and Sweat Glands
The sebaceous glands secrete sebum, an oily substance that helps keep skin from drying out. Sebum reduces water loss from the skin surface, protects the skin from infection by bacteria and fungi, and contributes to body odor. These glands are attached to hair follicles.
When your body gets hot or is under stress, sweat glands produce sweat, which evaporates to cool you. Sweat glands are located all over the body but are especially abundant in your palms, soles, forehead, and underarms. The apocrine glands are specialized sweat glands that emit an odor when the fluid comes in contact with bacteria normally found on your skin.