The skin is more than a simple barrier against the environment. It is composed of several types of cells with different functions each.
1. To start, the most obvious component is the squamous epithelial cells: these are basically cells filled with keratin. As cells from the deeper portion of the skin migrate outward towards the epidermis, their keratin content increases until they become totally filled. Function: they serve as a tough protection from the environment. Soon, they die out and are shed off.
2. Melanocytes: these cells produce melanin; depending on how much melanin you have, you can be dark or light-skinned. Function: protection from UV radiation. People who are overly light-skinned are more prone to have skin cancer than the darker-skinned ones.
3. Neural component. These include Merkel cells, Pacinian corpuscles, Meissner’s corpuscles and nerve endings. Function: to receive information about the environment such as light and deep pressure, temperature, vibration, touch sensation, etc…They transmit these signals to the nervous system so the body can react appropriately.
4. Dendritic cells: present in the epidermis and dermis and are capable of migrating to lymph nodes. Function: immunologic protection.
5. Lymphocytes: there are T and B lymphocytes whose functions are similar yet work via different means. B lymphocytes are responsible for humoral immunity while the T lymphocytes are for cell-mediated immunity; the latter deal with helper cells and cytotoxic cells to manage infectious agents.
6. Sweat glands, sebaceous glands and hair follicles. Sweat glands are coiled tubular structures that are situated in the dermis. On the other hand, hair follicles are in the epidermis and are associated with sebaceous glands. Function: sweat glands regulate temperature by secreting out water and sodium. Sebaceous glands secrete oil out the same pores that contain hair. They moisten the skin.