human anatomy, 3rd edition prentice hall, © 2001 the integumentary system chapter 4

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Integumentary System

Chapter 4

Human Anatomy, 3rd editionPrentice Hall, © 2001

Introduction– Structure

• Epidermis

• Dermis

• Hypodermis

– Functions of the skin

Human Anatomy, 3rd editionPrentice 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 editionPrentice 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 editionPrentice Hall, © 2001

Structure of the Skin– 2 principal parts

• Epidermis

• Dermis

– Beneath the dermis

• Subcutaneous layer

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Skin

Human Anatomy, 3rd editionPrentice 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 editionPrentice Hall, © 2001

Epidermis

Human Anatomy, 3rd editionPrentice Hall, © 2001

Epidermis

Human Anatomy, 3rd editionPrentice 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 editionPrentice Hall, © 2001

Pigments– Melanin

• Produced by melanocytes

• Skin color varies

• Protect skin from UV rays

– Carotene– Albino

Human Anatomy, 3rd editionPrentice Hall, © 2001

Melanocytes and Melanin

Human Anatomy, 3rd editionPrentice Hall, © 2001

Melanocytes and Melanin

Human Anatomy, 3rd editionPrentice 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 editionPrentice Hall, © 2001

Dermis

– Largest part of the skin

– Connective tissue

– Contains

• Blood vessels

• Nerves

• Glands

• Hair follicles

Human Anatomy, 3rd editionPrentice 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 editionPrentice Hall, © 2001

Papillary Layer

Human Anatomy, 3rd editionPrentice Hall, © 2001

Fingerprints

Human Anatomy, 3rd editionPrentice 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 editionPrentice Hall, © 2001

Subcutaneous Layer– Loose connective tissue

• Packed with adipose cells

– Stabilizes position of skin

Human Anatomy, 3rd editionPrentice Hall, © 2001

The Skin

Human Anatomy, 3rd editionPrentice Hall, © 2001

Epidermal Derivatives– Hair

– Glands

– Nails

Human Anatomy, 3rd editionPrentice Hall, © 2001

Functions of Hair

– Protection

– Thermoregulation

– Sensory

– Minor role in humans

Human Anatomy, 3rd editionPrentice Hall, © 2001

Human Anatomy, 3rd editionPrentice Hall, © 2001

Hair Structure

– Shaft

• Superficial portion

– Root

• Below the surface

Human Anatomy, 3rd editionPrentice 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 editionPrentice Hall, © 2001

Hair Structure

Human Anatomy, 3rd editionPrentice Hall, © 2001

Hair Structure– Hair develops in follicles

• Downward continuation of epidermis

Human Anatomy, 3rd editionPrentice 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 editionPrentice Hall, © 2001

Hair Follicle

Human Anatomy, 3rd editionPrentice Hall, © 2001

Arrector Pili– Smooth muscle attaches to follicle– Raises hairs– Response to fright or cold– Function?

Human Anatomy, 3rd editionPrentice Hall, © 2001

Glands– Sebaceous glands

• Connected to hair follicles

• Secrete a waxy, oily substance (sebum)– Blackheads

• Secretion increases at puberty

Human Anatomy, 3rd editionPrentice Hall, © 2001

Sebaceous Glands

Human Anatomy, 3rd editionPrentice Hall, © 2001

Glands– Sweat glands

• Found just about everywhere

• Produce “perspiration”

– Water, salt, met. Wastes

• Function – cooling of the body

Human Anatomy, 3rd editionPrentice Hall, © 2001

Glands– Scent Glands

• Specific type of sweat gland

• Found near hair follicles

– Axillary & genital regions

• Develop at puberty

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The Skin with Sweat Glands

Human Anatomy, 3rd editionPrentice Hall, © 2001

Nails– Dorsal surfaces of ends of fingers & toes– Primate feature– Grasping

Human Anatomy, 3rd editionPrentice Hall, © 2001

Nail Structure– Nail body– Free edge– Nail root

• Matrix– Lunula (moon)

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Nail Structure

Human Anatomy, 3rd editionPrentice Hall, © 2001

Skin Cancer– Basal Cell Carcinoma

– Squamous Cell Carcinoma

– Melanoma

Human Anatomy, 3rd editionPrentice Hall, © 2001

Basal Cell Carcinoma

Human Anatomy, 3rd editionPrentice Hall, © 2001

Squamous Cell Carcinoma

Human Anatomy, 3rd editionPrentice Hall, © 2001

Melanoma