ESSENTIALS

Unit

2Integumentary System (Skin)

ESSENTIALS

OF HUMAN

ANATOMY

& PHYSIOLOGY

Integumentary System

�Skin (cutaneous membrane)

�Skin derivatives

�Sweat glands

�Oil glands

�Hairs�Hairs

�Nails

Skin Functions

�Protects deeper tissues from:�Mechanical damage

�Chemical damage

�Bacterial damage

�Thermal damage

�Ultraviolet radiation�Ultraviolet radiation

�Desiccation

�Aids in heat regulation

�Aids in excretion of urea and uric acid

�Synthesizes vitamin D

Skin Structure

�Epidermis- outer layer

�Stratified squamousepithelium

�Keratinized

�Dermis

Dense connective�Dense connective

tissue

Layer of Epidermis

�Stratum basale�Cells undergoing mitosis

�Next to dermis

�Stratum spinosum

�Stratum granulosum

�Stratum lucidum�Occurs only in thick skin

�Stratum corneum�Shingle-like dead cells

Dermis

�Two layers�Papillary layer�Projections called dermal papillae

�Pain receptors

�Capillary loops

�Reticular layer�Reticular layer�Blood vessels

�Glands

�Nerve receptors

Hypodermis

�Deep to dermis

�Not part of the skin

�Anchors skin to underlying organs

�Mostly adipose tissue

Skin Structure

Skin Renewal

Normal Skin Color Determinants�Melanin�Pigment produced by melanocytes

�Melanocytes are mostly in the stratum basale

�Yellow, brown or black pigments

�Genetics and sunlight exposure

�Carotene�Carotene�Orange-yellow pigment in some vegetables

�Hemoglobin�Red coloring (blood cells in capillaries)

�Oxygen content determines the extent of red coloring

Skin Color Variation

Appendages of the Skin

�Sebaceous glands�Produce oil� Lubricate skin

�Kill bacteria

�Most ducts empty into hair follicles

�Activated at puberty�Activated at puberty

Appendages of the Skin

�Sweat glands

�Widely distributed in skin

�Eccrine (most numerous)

� Open via duct to pore on skin surface

�Apocrine

� Ducts empty into hair follicles� Ducts empty into hair follicles

Sweat and Its Function

�Composition�Mostly water

�Some metabolic waste

�Fatty acids and proteins (apocrine only)

�Function�Dissipate excess heat�Dissipate excess heat

�Excrete waste products

�Acidic nature inhibits bacteria growth

�Odor is from associated bacteria

Heat Regulation

Appendages of the Skin

�Hair�Produced by hair bulb

�Consists of hard keratinized epithelial cells

�Melanocytes provide pigment for hair color

Hair Anatomy

�Central medulla

�Cortex surrounds medulla

�Cuticle outer layer�Most heavily keratinized

Associated Hair Structures

�Hair follicle�Dermal and epidermal

sheath surround hair root

�Arrector pili�Smooth muscle

�Sebaceous gland�Sebaceous gland

�Sweat gland

Appendages of the Skin

�Nails

�Scale-like modifications of the epidermis

�Heavily keratinized

�Stratum basale extends beneath nail bed

�Responsible for growth

�Colorless- lack of pigment�Colorless- lack of pigment

Nail Structures

�Free edge

�Body

�Root of nail

�Eponychium- proximal nail fold that projects onto the nail bodyprojects onto the nail body