Integumentary System Epidermis o o o Outer layer

Integumentary System

Epidermis o o o 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 o o o Next to basement membrane and blood supply Active mitosis Contain melanocytes

Stratum spinosum o o Consists of several layers Spiny projections extend down to connect layers together

Stratum germinativum o Composed of two layers: n Stratum basale n Stratum spinosum

Stratum granulosum o o 2 -3 layers of flattened cells Keratinization begins here

Stratum Lucidum o o Translucent 2 -3 layers Only found in thick skin

Stratum corneum o o o Outermost layer ¾ of thickness 20 -30 layers Cells are completely keratinized 5 week life cycle

Dermis

Dermis o o Stratum corium Made of dense connective tissue Papillary layer Reticular layer

Subcutaneous layer o o o Anchors skin Loose connective and adipose tissues Also called hypodermis or superficial fascia

Skin Color

Functions o o Protection Sensory reception Regulation of body temperature Synthesis of vitamin D

Epidermal Derivatives o Hair and hair follicles o Nails o Glands

Hair and hair follicles o o Composed of dead, keratinized cells Produced from stratum basale Color determined by melanin production Texture determined by shape of hair shaft

Nails o o Layers of dead stratum corneum Stratum basale forms nail bed

Glands o Three types: n Sebaceous n Sudoriferous n Ceruminous

Sebaceous glands o o o 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 o o o Sweat glands Located everywhere except the lips, nipples, and parts of the external genitalia Merocrine and apocrine glands

Ceruminous glands o o Modified sweat glands in the ear canal Secrete cerumen

ABCD Rule for Moles

Burns o o First degree Second degree Third degree Rule of nines

First degree burn

Second degree burn

Third degree burn