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

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

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

Skin Color

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

ABCD Rule for Moles

Burns First degree Second degree Third degree Rule of nines

First degree burn

Second degree burn

Third degree burn