Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Fundamentals of Anatomy & Physiology Frederic H. Martini Lecture 5:Chapter 5 The Integumentary System Pages: Lecturer: Dr. Barjis Room P313 Phone: (718)

Learning Objectives List the components of the integumentary system, including their physical relationships. Specify the functions of the integumentary system. Describe the main features and functions of the epidermis and dermis. Discuss individual and racial differences in skin. Discuss the effects of UV light on the epidermis. Explain the structure and function of the various accessory organs of the skin. Explain how the skin responds to injury and aging.

Cutaneous membrane Epidermis Dermis Accessory structures Subcutaneous layer The Integumentary System: An Overview The integumentary system consists of

Protection Excretion Temperature maintenance Nutrient storage Vitamin D3 synthesis Sensory detection Integumentary system functions:

The Components of the Integumentary System

The epidermis is composed of layers of keratinocytes Thin skin = four layers (strata) Thick skin = five layers The Epidermis Thin Skin and Thick Skin

Provides mechanical protection Prevents fluid loss Keeps microorganisms from invading the body The epidermis

Stratum germinativum Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum Layers of the epidermis:

The Epidermal Ridges of Thick Skin

Cells accumulate keratin and eventually are shed Epidermal ridges are interlocked with dermal papillae Fingerprints Improve gripping ability Langerhans cells (immunity) in s. spinosum Merkel cells (sensitivity) in s. germinativum Epidermal characteristics:

The Structure of the Epidermis

Blood supply Carotene and melanin Melanocytes produce melanin and protect from UV radiation Epidermal pigmentation Interrupted blood supply leads to cyanosis Skin color depends on

Melanocytes

Synthesize vitamin D3 (cholecalciferol) when exposed to UV Respond to epidermal growth factor Growth Division Repair Secretion Epidermal cells

Papillary layer Contains blood vessels, lymphatics, sensory nerves of epidermis Reticular layer Contains network of collagen and elastic fibers to resist tension The Dermis Dermal Organization

Dermal Circulation

Caused by excessive stretching of the dermis Patterns of collagen and elastic fibers form lines of cleavage Stretch marks

Lines of Cleavage of the Skin

Cutaneous plexus arteries found in subcutaneous layer/ papillary dermis Cutaneous sensory receptors (light touch, pressure) Dermal Circulation and innervation

Stabilizes skins position against underlying organs and tissues The Subcutaneous Layer Hypodermis

Originate in hair follicle Composed of root and shaft Root base (hair papilla) surrounded by hair bulb and root hair plexus Hairs have soft medulla and hard cortex Cuticle = superficial dead protective layer Accessory Structures Hairs

the Anatomy of a Single Hair

Vellus hairs (peach fuzz) Terminal hairs ( heavy) Club hair (cessation of growth) Shed and grow according to hair growth cycle Arrector pili muscle attaches to hair Hair types

Hair Follicles

Sebaceous Suderiferous Mammary Ceruminous Glands in the skin

Discharge waxy sebum onto hair shaft when associated with hairs Sebaceous follicles discharge onto epidermal surface Sebaceous glands

Sebaceous Glands and Follicles

Apocrine sweat glands Produce odorous secretion Merocrine (eccrine) sweat gland Sensible perspiration Suderiferous glands

Sweat Glands

Mammary glands Structurally similar to apocrine sweat glands Ceruminous glands In ear, produce waxy cerumen Other glands

Nail body covers the nail bed Nail production occurs at the nail root Eponychium (cuticle) overlies root Free edge of nail extends over hyponychium Nails

The Structure of a Nail

Regenerates easily Regeneration process includes formation of Scab Granulation tissue Scar tissue Local Control of Integumentary Function Injury and repair

Integumentary Repair

Integument thins Blood flow decreases Cellular activity decreases Repairs occur more slowly Aging and the Integumentary System With age

The components of the integumentary system, including their physical relationships. The functions of the integumentary system. The main features and functions of the epidermis and dermis. Individual and racial differences in skin. The effects of UV light on the epidermis. The structure and function of the various accessory organs of the skin. How the skin responds to aging. You should now be familiar with: