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Integumentary system (Epidermis (Stratum Basale - This bottom-most layer…
Integumentary system
Epidermis
Stratum Granulosum - This layer has one to five layers of flattened keratinocytes. Cells in this layer contain keratohyalin granules and lamellar granules.
Stratum Lucidum - This layer only exists in people with thick skin. It consists of a few rows of dead keratinocyte cells.
Stratum Spinosum - This layer is several layers thick of keratinocytes and also contains dendritic cells that are part of the immune system
Stratum Basale - This bottom-most layer of the epidermis includes stem cells and melanin cells, this layer helps to protects us from UV rays,
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Stratum Corneum - This is the outermost layer of the epidermis and consists of mostly dead keratinocytes cells. It's function is to protect the skin and make it waterproof.
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Appendages
Hair & Hair Folicles - Hair is the flexible strand made up of dead cells filled with hard keratin. Hair is comprised of the root and the shaft. Hair also has 3 layers of cells: the Medulla, Cortex, and Cuticle.
Hair Folicles are embedded into the dermis and are what the hair shaft grows out of. Hair Folicles consist of the hair bulb and the hair follicle receptor.
Sebaceous Glands - these are the skin's oil glands and they produce sebum.This keeps the epidermis moist and prevents cracking. It also helps to slow water loss and to kill bacteria.
Nails - This is a modification of the epidermis made up of dead, hard keratinized cells. These are more rigid and durable and do not flake like the soft keratin found in epidermal cells.
Sweat Glands - sweating cools the body and prevents is from overheating. As sweat evaporates, it cools the skin.There are 2 kinds of sweat glands: eccrine and apocrine. Eccrine glands secrete sweat through ducts that open directly onto the surface of the skin and are the most common type of seat gland. Apocrine glands are larger and are mostly in the axillary, anal, and genital areas.Sweat is secreted through apocrine ducts directly into the hair folicle.
Dermis
Papillary Dermis - This consists of the top 20% of the dermis and is made up of thin collagen and elastic fibers
Reticular Dermis - This is the bottom 80% of the dermis. It is made up of thick collagen and elastic fibers that give skin strength & resiliancy. It also has a lot of nerve fibers and blood vessels.
Hemoglobin is present in the capillaries contained in the reticular dermis. It is hemoglobin which gives Caucasians a pink glow to their skin.
Hypodermis - This is located under the dermis and is comprised of mainly adipose, or fatty tissue. This also acts as an insulator to prevent heat loss.
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