2. Chapter 4

3. The Skin and Its Parts

4. Applied Learning Objectives
Use the terminology associated with the integumentary system
Learn about skin structure, function, appendages, glands, and care
Understand the aging and pathology of the integumentary system

5. Introduction
The integumentary system is a dynamic continuous body covering composed of:
blood vessels
connective tissue structures
glands
hair
nails
skin

6. Skin Structure Human skin has three distinct layers: epidermis dermis
hypodermis (or subcutaneous layer)
Epidermis The outermost layer of skin
Dermis The middle layer of skin, formed from mesenchyme cells
Hypodermis or Subcutaneous Layer The innermost layer of skin

7. Skin Appendages
Skin appendages are complex structures that assist the skin with its functions.
These appendages include glands, nerves, nails, and hair.

8. Functions of the Integumentary System
The four main functions of the integumentary system are:
protection
barrier against chemical, mechanical, and microbial damage
heat regulation
maintains constant internal temperature
sensation
receives stimuli from the environment
waste excretion
sweat contains organic chemicals, salts, and urea
Protection describes that the skin is a barrier against chemical, mechanical and microbial damage.
Heat regulation is the body’s ability to maintain a constant internal temperature.
Sensation describes the ability of the skin to receive stimuli from the environment and interpret it in a way that the brain can comprehend.
Waste excretion is handled primarily by eccrine sweat glands which excrete urea, organic chemicals, and excess salts.

9. Discussion Question
What specific examples can you provide of how the skin protects the body?
Students should provide specific examples of how the skin protects the body. Examples include: sensing if an object is too hot to hold for a prolonged period; sweating to cool the body; etc.

10. Wellness and Illness over the Life Span
Pathology can be categorized as:
degenerative
genetic
infectious
Aging is due to:
intrinsic factors
extrinsic factors
lifestyle
Degenerative Diseases Refers to diseases that progressively deteriorate tissues (such as skin cancers, moles, and skin tags)
Genetic Disorder Refers to a genetic mutation or mutations that diminish body functions (such as acne, psoriasis, and spider veins)
Infectious Disease A disease caused by microorganisms that damage
tissues and organs (such as impetigo, ringworm, and warts)
Intrinsic Aging Factor Aging caused by the natural decline of cells
Extrinsic Aging Factor or External Aging Factor Aging caused by environmental elements

11. Summary
The skin is composed of three distinct layers: the epidermis, the dermis, and the hypodermis (subcutaneous).
The integumentary system contains many appendages, including several kinds of glands, nerves, nails, and hair.
The functions of the skin are to protect the body from damage, help regulate body temperature, detect sensory cues, and assist in waste removal.
Epidermis The outermost layer of skin
Dermis The middle layer of skin, formed from mesenchyme cells
Hypodermis or Subcutaneous Layer The innermost layer of skin
Appendages Complex structures that assist skin function