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Daphne Sumodlayon posted an update in the group
MT30-Histology Art AB 3 years, 8 months ago The integumentary system is the set of organs forming the outermost layer of the human body. It comprises the skin and its appendages, acting as a physical barrier between the external environment and the internal environment that it serves to protect and maintain the body of the animal.
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Structure of the 5 layers of the skin
Stratum corneum – outermost layer composed of 20-30 layers of dead, flattened cells; anucleate, keratin-filled keratinocytes which protect against friction and water loss
Stratum lucidum – 2-3 layers of anucleate, dead cells; seen only in thick skin on the palm of the hands and fingers, and soles of the feet
Stratum granulosum – 3-5 layers of keratinocytes with distinct keratohyalin granules; keratinocytes produce lipids and a natural moisturizing factor that makes the skin waterproof and holds moisture
Stratum spinosum – several layers of keratinocytes all joined by desmosomes to prevent the skin from tearing and blistering; Langerhans cells are present
Stratum basale – deepest, a single layer of cuboidal to low columnar cells in contact with basement membrane; mitosis occurs here; melanocytes and Merkel cells are present
Structure of the nail
Root – appears as a white crescent (lunula); embedded in the skin and adheres to an epithelial nail bed; produces most of the volume of the nail
Nail bed – an extension of the stratum basale beneath the nail; contains blood vessels, nerves, and melanocytes that produce melanin
Body – visible attached portion
Free edge – grows out away from the body
Nail fold – skin folds that overlap the borders of the nail
Eponychium – thick proximal nail fold commonly called the cuticle
Nail matrix – thickened proximal part of the nail bed containing germinal cells responsible for nail growth
Lunula – proximal region of the thickened nail matrix, which appears as a white crescent