About Your Skin
For your convenience, we have put together several short, informative articles on skin care to help you understand the changes your skin can go through over time and what can be done to correct or reverse these changes. We have also included a Self-Assessment Exercise that may help you identify problem areas in your own skin — problems that we may be able to correct.
A Brief Tour of the Skin
Your skin is your largest sensory organ. It transmits touch, pressure, pain, and temperature signals to your brain. It is part of the integumentary system, which also includes fingernails and sweat and oil glands. It provides the primary protective barrier between your body and the environment. It also helps to regulate body temperature and minimize evaporative fluid loss. Skin pigment provides protection from ultraviolet light (UV).
The skin is composed of three layers:
Epidermis - the outer layer: The translucent epidermis contains several cell layers. The outer “horny layer,” consists of flattened, rough, dead cells. These outer cells shed regularly and are replaced by new cells formed in the deepest epidural layer. This layer also contains the pigment-producing cells. The look of your skin can be improved by removing most of the rough outer cells (exfoliation).
Dermis - the central layer: The dermis is the tough, resilient layer of your skin, made up of interlaced fibrous tissue. It contains blood and lymph vessels, sensory nerves, sweat glands and ducts, sebaceous (oil) glands, and hair roots, bulbs, and follicles. Small muscles in this layer contract in response to cold, pulling the follicles upright (goose bumps).
Hypodermis - the bottom layer: The deep hypodermis binds the skin to the body and provides cushioning and insulation. It contains fibrous connective tissue, fat cells, and blood vessels.
Melanin, carotene, and hemoglobin all contribute to skin color. Melanosome pigment is the primary determinant; located in each cell, it darkens when exposed to UV radiation (primarily sunlight) and also protects the cell. The size of melanosome granules, rather than the quantity, determines overall skin color. Carotene, found in the dermis and hypodermis, is the orange pigment in vegetables such as carrots and sweet potatoes; it is most visible in thick skin, such as on the palms of the hands. Hemoglobin, the iron-containing protein of red blood cells, adds pink color from oxygenated blood in the dermis.
The dermis is comprised mostly of structural collagen protein, which forms horizontal bundles held together by elastin fibers. These collagen bundles are surrounded by hyaluronic acid, which helps retain water to plump the skin and keep it supple. As we age, production of collagen, elastin, and hyaluronic acid declines; subcutaneous fat thins; and facial muscles atrophy. The result is a loss of elasticity and the ability to maintain hydration. Add gravity and motion, and the skin sags and wrinkles. When the skin is injured (grazed or cut, for example), it heals itself by forming new collagen.