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Integumentary System. Epidermis. Outer layer of skin Stratified squamous Has no blood supply Cells go through process of keratinization Regular skin has four strata Thick skin has five strata. Stratum basale. Next to basement membrane and blood supply Active mitosis Contain melanocytes.
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Epidermis • Outer layer of skin • Stratified squamous • Has no blood supply • Cells go through process of keratinization • Regular skin has four strata • Thick skin has five strata
Stratum basale • Next to basement membrane and blood supply • Active mitosis • Contain melanocytes
Stratum spinosum • Consists of several layers • Spiny projections extend down to connect layers together
Stratum germinativum • Composed of two layers: • Stratum basale • Stratum spinosum
Stratum granulosum • 2-3 layers of flattened cells • Keratinization begins here
Stratum Lucidum • Translucent 2-3 layers • Only found in thick skin
Stratum corneum • Outermost layer • ¾ of thickness • 20-30 layers • Cells are completely keratinized • 5 week life cycle
Dermis • Stratum corium • Made of dense connective tissue • Papillary layer • Reticular layer
Subcutaneous layer • Anchors skin • Loose connective and adipose tissues • Also called hypodermis or superficial fascia
Functions • Protection • Sensory reception • Regulation of body temperature • Synthesis of vitamin D
Epidermal Derivatives • Hair and hair follicles • Nails • Glands
Hair and hair follicles • Composed of dead, keratinized cells • Produced from stratum basale • Color determined by melanin production • Texture determined by shape of hair shaft
Nails • Layers of dead stratum corneum • Stratum basale forms nail bed
Glands • Three types: • Sebaceous • Sudoriferous • Ceruminous
Sebaceous glands • Found everywhere there is hair • Holocrine glands • Secrete sebum • Keeps skin and hair pliable • Inhibits bacterial growth and helps prevent water loss • Activated by increased sex hormones
Sudoriferous glands • Sweat glands • Located everywhere except the lips, nipples, and parts of the external genitalia • Merocrine and apocrine glands
Ceruminous glands • Modified sweat glands in the ear canal • Secrete cerumen
Burns • First degree • Second degree • Third degree • Rule of nines