Chapter 5, part 1

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

Fundamentals of

Anatomy & PhysiologySIXTH EDITION

Chapter 5, part 1

The Tissue Level of Organization--Integument


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.


SECTION 5-1 The Integumentary System: An Overview


• Cutaneous membrane

• Epidermis

• Dermis

• Accessory structures

• Subcutaneous layer

The integumentary system consists of


• Protection

• Excretion

• Temperature maintenance

• Nutrient storage

• Vitamin D3 synthesis

• Sensory detection

Integumentary system functions:


Figure 5.1 The Components of the Integumentary System

Figure 5.1


SECTION 5-2 The Epidermis


• The epidermis is composed of layers of keratinocytes

• Thin skin = four layers (strata)

• Thick skin = five layers

Figure 5.2 Thin Skin and Thick Skin

Figure 5.2


• 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:

Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.3

Figure 5.3 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:


Figure 5.4 The Structure of the Epidermis

Figure 5.4


• 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


Figure 5.5 Melanocytes

Figure 5.5a, b


• Synthesize vitamin D3 (cholecalciferol) when exposed to UV

• Respond to epidermal growth factor

• Growth

• Division

• Repair

• Secretion

Epidermal cells


SECTION 5-3The Dermis


• Papillary layer

• Contains blood vessels, lymphatics, sensory nerves of epidermis

• Reticular layer

• Contains network of collagen and elastic fibers to resist tension

Dermal Organization


Figure 5.8 Dermal Circulation

Figure 5.8


• Caused by excessive stretching of the dermis

• Patterns of collagen and elastic fibers form lines of cleavage

Stretch marks


Figure 5.7 Lines of Cleavage of the Skin

Figure 5.7


• Cutaneous plexus arteries found in subcutaneous layer/ papillary dermis

• Cutaneous sensory receptors (light touch, pressure)

Dermal Circulation and innervation

Chapter 5, part 1

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