1. Chapter 60 Structure and Function of the Skin

2. Functions of the Skin Prevents body fluids from leaving the body
Protects the body from potentially damaging environmental agents
Serves as an area for heat exchange
Provides protection against invading microorganisms

3. Role of Receptors in the Skin
Relay the following sensations to the CNS for localization and discrimination:
Pressure
Temperature
Pain

4. Layers of the Skin Outer epidermis
Avascular layer composed of 4–5 layers of stratified squamous keratinized epithelial cells formed in the deepest layer of the epidermis
These cells migrate to the skin surface to replace cells lost during normal shedding.
Basement membrane
Thin adhesive layer cementing the epidermis to the dermis
Layer involved in blister formation

6. Layers of the Skin (cont.)
Inner dermis
Connective tissue layer that separates the epidermis from the underlying subcutaneous fat layer
Contains blood vessels and nerve fibers that supply the epidermis

7. Cells of the Epidermis Keratinocytes Melanocytes Merkel cells
Langerhans cells

10. Papillary Dermis Definition
A thin, superficial layer that lies adjacent to the epidermis
Composition
Consists of collagen fibers and ground substance
This layer is densely covered with conical projections called dermal papillae.

11. Papillary Dermis (cont.)
Function
Minimizes the separation of the dermis and the epidermis
Nourishes the epidermal layers of the skin

12. Reticular Dermis Definition
The thicker area of the dermis that forms the bulk of the dermal layer
Composition
Complex meshwork of three-dimensional collagen bundles interconnected with large elastic fibers and ground substance
A viscid gel that is rich in mucopolysaccharides

13. Question Which of the following is not found in the epidermis?
Keratinocytes
Melanocytes
Merkel cells
Langerhans cells
Blood vessels

14. Answer Keratinocytes Melanocytes Merkel cells Langerhans cells
Blood vessels: Blood vessels are found in the dermal layer.

15. Skin Appendages Hair Nails Sebaceous glands Eccrine glands
Apocrine glands

16. Types of Sweat Glands Eccrine sweat glands
Simple tubular structures that originate in the dermis and open directly to the skin surface
Numerous (several million) and vary in density
Located over the entire body surface
Transport sweat to the outer skin surface to regulate body temperature

18. Types of Sweat Glands (cont.)
Apocrine sweat glands
Less numerous than eccrine sweat glands
Larger and located deep in the dermal layer
Open through a hair follicle, even though a hair may not be present
Found primarily in the axillae and groin

19. Apocrine gland Hair papilla Sebaceous gland Arrector pili muscle
Which of the following structures would likely be present in a hair follicle in a man’s groin but not on the face?
Apocrine gland
Hair papilla
Sebaceous gland
Arrector pili muscle

20. Apocrine gland

21. Secretions of the Sebaceous Glands
Lipids, including triglycerides
Cholesterol
Wax

22. Nails Definition Hardened keratinized plates Function
Protect the fingers and toes and enhance dexterity

23. Immune Cells Found in the Dermis
Macrophages
T cells
Mast cells
Fibroblasts

24. Skin Rashes and Lesions
Macule
Patch
Papule
Plaque
Nodule
Tumor
Wheal

26. Skin Rashes and Lesions (cont.)
Vesicle
Bulla
Pustule
Blister
Calluses
Corns

27. Pruritus or Itchy Sensation
Originates in free nerve endings in the skin
Carried by small myelinated type C nerve fibers
Itch and pain are antagonistic
Causes
Histamine
Tryptase
Opioids
Neuropeptides
Substance P
Bile salts
Bradykinin

28. Xerosis Dry skin Dehydration of the stratum corneum
Aging skin will be dry due to a change in the composition of sebaceous gland secretions and a decrease in the secretion of moisture from the sweat glands.
Moisturizing agents are the cornerstone of treatment for dry skin.
Emollients
Humectants
Occlusives

29. Dark Skin Variations
Because of their skin color, dark-skinned persons are better protected against skin cancer, premature wrinkling, and aging of the skin that occurs with sun exposure.
Problems
Ashy skin
Hypo- and hyperpigmentation

30. Question Is the following statement true or false?
The pathology of itchy skin is well understood.

31. Question
False: The pathology of itchy skin is not well understood.

32. Case study
Explain the anatomic and functional differences between eccrine and apocrine glands.
What autonomic nervous system controls the function of thermoregulation of the skin? How do goose bumps contribute to heat conservation?
Describe the location of the blood plexuses in the skin. How is blood circulation to the skin involved in thermoregulation

33. Case study Typical signs and symptoms of a fracture?
How does a hematoma form and what function it serve in the healing function?
Describe the muscular and joint changes in immobilization?