Thick and thin skin appear differently under a microscope. Thin skin contains four layers in the epidermis, while thick skin contains a fifth layer. These layers include :. The stratum basale, also known as the stratum germinativum, is the deepest layer of the epidermis. It is the layer just above the dermis. This layer continuously produces new skin cells. It also contains melanocytes, which are cells that produce skin pigment and help protect the skin from sun damage. The stratum spinosum consists of eight to ten layers of cells.
People may refer to the stratum spinosum as the prickle cell layer because of the irregular structure of cells, which look like spines or prickles. The stratum granulosum consists of three to five layers of cells.
The stratum granulosum contains granules, which are rich in lipids. Only thick skin contains the stratum lucidum layer. The stratum lucidum is a thin, transparent layer consisting of two to three layers of cells.
It contains a protein called eleidin. The stratum corneum is the upper layer of the epidermis. It consists of 20—30 layers of cells. It contains keratin and horny scales, which make it tougher and able to thicken into calluses.
The stratum corneum contains dead keratinocytes, which produce defensins. Defensins are strings of amino acids that protect the body from infection. Connecting the dermis and epidermis are structures called dermal papillae. Dermal papillae are more prominent in thick skin than thin skin. Dermal papillae increase the surface area between the epidermis and dermis, allowing for more oxygen, food, and waste to pass between the layers.
Skin in general has many different functions, such as protection, sensation, and thermoregulation. Both thin and thick skin have properties that allow the skin to function correctly.
For example, thin skin contains hair follicles, which are important in producing hair to help regulate temperature and protect from ultraviolet radiation. Hair follicles also provide epithelial stem cells, which help repair wounds. In addition, thin skin contains sebaceous glands, which produce sebum. Sebum helps to lubricate the skin and protect against infections. Thin skin also contains eccrine and apocrine sweat glands. Sweat glands help to regulate body temperature by releasing sweat to cool the body, and also help to repair skin damage.
On the back, it can be 3. There are no distinct layers in this part of the skin, but more or less two regions that differ in the types of fibers that spread throughout them. The outer part has thin, delicate collagen fibers, while the inner part has rougher and tougher collagen fibers that are arranged like a mesh reticulum parallel to the surface.
Furthest from the outside is the hypodermis , panniculus adiposus or subcutaneous tissue. This is a layer of adipocyte cells and connective tissue that stores large amounts of lipids and thus carries out the two important functions of energy storage and thermal insulation.
Click here to. Components of Cells. The Macromolecules. The principal cells of the epidermis are keratinocytes. The basal cells or "stem cells" of the epidermis are undifferentiated, proliferating cells that migrate upwards through all the five layers in a process known as keratinization. It takes about 30 days for the cells to migrate from the basal layer to cross the stratum corneum where they are finally shed.
Epidermis varies in thickness throughout the body depending mainly on frictional forces and is thickest on the palms of the hands and soles of the feet, and thinnest in the face eyelids and genitalia.
The dermis is a tough but elastic support structure that houses nerves, blood vessels, lymphatics, and cutaneous appendages pilosebaceous units, eccrine and apocrine sweat glands. It is thicker averages 1 to 4 mm than the epidermis which is about as thin as piece of paper. The dermis varies in thickness.
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