Human Anatomy, 3rd edition Prentice Hall, © 2001 The Integumentary System Chapter 4

Human Anatomy, 3rd edition Prentice Hall, © 2001 Introduction –Structure Epidermis Dermis Hypodermis –Functions of the skin

Human Anatomy, 3rd edition Prentice Hall, © 2001 The “Birthday Suit” –Combination of 4 main tissues Epithelial – outer layer Connective – underlies dermis Smooth Muscle – goose bumps Nervous – sensory receptors

Human Anatomy, 3rd edition Prentice Hall, © 2001 Functions of the Skin –Protection –Temperature regulation –Sensations –Storage of chemical compounds –Excretion of wastes –Synthesis of compounds –Determines characteristics

Human Anatomy, 3rd edition Prentice Hall, © 2001 Structure of the Skin –2 principal parts Epidermis Dermis –Beneath the dermis Subcutaneous layer

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Skin

Human Anatomy, 3rd edition Prentice Hall, © 2001 Epidermis –Stratified squamous epithelium –Over most of the body it’s thin –Approximately every month we shed entire skin surface

Human Anatomy, 3rd edition Prentice Hall, © 2001 Epidermis

Human Anatomy, 3rd edition Prentice Hall, © 2001 Epidermis

Human Anatomy, 3rd edition Prentice Hall, © 2001 Replacement of Epidermal Cells –Base of epidermis Cuboidal cells divide by mitosis New cells are pushed toward surface –New epidermal cells produce keratin –Cells are flattened as they are pushed upwards –Cells die –Outermost layer Cells are dead, filled with keratin –Takes about two weeks for an epidermal cell to move from the bottom layer to the top

Human Anatomy, 3rd edition Prentice Hall, © 2001 Pigments –Melanin Produced by melanocytes Skin color varies Protect skin from UV rays –Carotene –Albino

Human Anatomy, 3rd edition Prentice Hall, © 2001 Melanocytes and Melanin

Human Anatomy, 3rd edition Prentice Hall, © 2001 Melanocytes and Melanin

Human Anatomy, 3rd edition Prentice Hall, © 2001 Epidermis and Dermis –Epidermis is avascular –Dermis is highly vascular –Epidermis receives nourishment from dermis –Cells far away from nourishment die

Human Anatomy, 3rd edition Prentice Hall, © 2001 Dermis –Largest part of the skin –Connective tissue –Contains Blood vessels Nerves Glands Hair follicles

Human Anatomy, 3rd edition Prentice Hall, © 2001 Papillary Layer of the Dermis –Most superficial layer –Surface area increased by papillae Form fingerprints –Has lots of sensory receptors Papillary Layer

Human Anatomy, 3rd edition Prentice Hall, © 2001 Papillary Layer

Human Anatomy, 3rd edition Prentice Hall, © 2001 Fingerprints

Human Anatomy, 3rd edition Prentice Hall, © 2001 Deeper Layer of the Dermis –Deeper layer –Dense connective tissue –Contains Blood vessels Glands Deep pressure receptors –Attached to underlying organs by the subcutaneous layer

Human Anatomy, 3rd edition Prentice Hall, © 2001 Subcutaneous Layer –Loose connective tissue Packed with adipose cells –Stabilizes position of skin

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Skin

Human Anatomy, 3rd edition Prentice Hall, © 2001 Epidermal Derivatives –Hair –Glands –Nails

Human Anatomy, 3rd edition Prentice Hall, © 2001 Functions of Hair –Protection –Thermoregulation –Sensory –Minor role in humans

Human Anatomy, 3rd edition Prentice Hall, © 2001

Human Anatomy, 3rd edition Prentice Hall, © 2001 Hair Structure –Shaft Superficial portion –Root Below the surface

Human Anatomy, 3rd edition Prentice Hall, © 2001 Hair Structure –Medulla Soft core of hair –Cortex Hard core that gives hair its stiffness –Cuticle Outermost layer of hair

Human Anatomy, 3rd edition Prentice Hall, © 2001 Hair Structure

Human Anatomy, 3rd edition Prentice Hall, © 2001 Hair Structure –Hair develops in follicles Downward continuation of epidermis

Human Anatomy, 3rd edition Prentice Hall, © 2001 Growth of Hair –At the base of the follicle, hair papilla Contains blood vessels and nerves –Nourishes hair –Bulb Contains matrix – epithelial cells responsible for growth –Contains melanocytes

Human Anatomy, 3rd edition Prentice Hall, © 2001 Hair Follicle

Human Anatomy, 3rd edition Prentice Hall, © 2001 Arrector Pili –Smooth muscle attaches to follicle –Raises hairs –Response to fright or cold –Function?

Human Anatomy, 3rd edition Prentice Hall, © 2001 Glands –Sebaceous glands Connected to hair follicles Secrete a waxy, oily substance (sebum) –Blackheads Secretion increases at puberty

Human Anatomy, 3rd edition Prentice Hall, © 2001 Sebaceous Glands

Human Anatomy, 3rd edition Prentice Hall, © 2001 Glands –Sweat glands Found just about everywhere Produce “perspiration” –Water, salt, met. Wastes Function – cooling of the body

Human Anatomy, 3rd edition Prentice Hall, © 2001 Glands –Scent Glands Specific type of sweat gland Found near hair follicles –Axillary & genital regions Develop at puberty

Human Anatomy, 3rd edition Prentice Hall, © 2001 The Skin with Sweat Glands

Human Anatomy, 3rd edition Prentice Hall, © 2001 Nails –Dorsal surfaces of ends of fingers & toes –Primate feature –Grasping

Human Anatomy, 3rd edition Prentice Hall, © 2001 Nail Structure –Nail body –Free edge –Nail root Matrix –Lunula (moon)

Human Anatomy, 3rd edition Prentice Hall, © 2001 Nail Structure

Human Anatomy, 3rd edition Prentice Hall, © 2001 Skin Cancer –Basal Cell Carcinoma –Squamous Cell Carcinoma –Melanoma

Human Anatomy, 3rd edition Prentice Hall, © 2001 Basal Cell Carcinoma

Human Anatomy, 3rd edition Prentice Hall, © 2001 Squamous Cell Carcinoma

Human Anatomy, 3rd edition Prentice Hall, © 2001 Melanoma