1. Chapter 5 The Integumentary System
2/19/2009

2. Introduction
The organs of the integumentary system include the skin and its accessory structures including hair, nails, and glands, as well as blood vessels, muscles and nerves
Dermatology is the medical specialty for the diagnosis and treatment of disorders of the integumentary system.
2/19/2009

3. Structure of the Skin: Objectives
Describe the layers of the epidermis and the cells that compose them.
Compare the composition of the papillary and reticular regions of the dermis.
Name the tissue types composing the epidermis and dermis. List the major layers of each and describe their functions.
Explain the basis for different skin colors.
Briefly describe how changes in skin color may be used as clinical signs of certain disease states.
2/19/2009

4. Structure of the Skin
The skin (cutaneous membrane) covers the body and is the largest organ of the body by surface area and weight
Its area is about 2 square meters (22 square feet) and weighs 4.5-5kg (10-11 lb), about 16% of body weight
It is 0.5 – 4 mm thick, thinnest on the eyelids, thickest on the heels; the average thickness is 1 – 2 mm
2/19/2009

5. Structure of the Skin It consists of two major layers:
outer, thinner layer called the epidermis, consists of epithelial tissue
inner, thicker layer called the dermis
Beneath the dermis is a subcutaneous (subQ) layer (also called hypodermis) which attaches the skin to the underlying tissues and organs.
2/19/2009

6. Components of the Integumentary System
2/19/2009

7. Structure of the Skin
The epidermis has a number of important characteristics:
the epidermis is composed of keratinized stratified squamous epithelium
it contains four major types of cells: see next slide
2/19/2009

8. Structure of the Skin
Keratinocytes (90% of the cells) produce keratin which is a tough fibrous protein that provides protection
Melanocytes: which produce the pigment melanin that protects against damage by ultraviolet radiation
Langerhans cells: involved in immune responses, arise from red bone marrow
Merkel cells: which function in the sensation of touch along with the adjacent tactile discs
2/19/2009

9. Types of Cells in the Epidermis
2/19/2009

10. Epidermis
The epidermis contains four major layers (thin skin) or five major layers (thick skin)
Stratum basale (deepest layer) or stratum germinativum, where continuous cell division occurs which produces all the other layers
Stratum spinosum, 8-10 layers of keratinocytes
Stratum granulosum, which includes keratohyalin and lamellar granules
2/19/2009

11. Epidermis
Stratum lucidum is present only in thick skin (the skin of the fingertips, palms, and soles)
Stratum corneum: composed of many sub layers of flat, dead keratinocytes called or squames that are continuously shed and replaced by cells from deeper strata; constant friction can stimulate formation of a callus.
Keratinization, the accumulation of more and more protective keratin, occurs as cells move from the deepest layer to the surface layer
2/19/2009

12. Layers of the Epidermis
2/19/2009

13. Dermis The dermis has several important characteristics:
is composed of connective tissue collagen and elastic fibers
contains two layers
papillary region (upper layer immediately beneath epidermis) consists of areolar connective tissue containing thin collagen and elastic fibers, dermal papillae (including capillary loops), corpuscles of touch and free nerve endings
2/19/2009

14. Dermis
reticular region, the deep layer, consists of dense irregular connective tissue containing collagen and elastic fibers adipose cells, hair follicles, nerves, sebaceous (oil) glands, and sudoriferous (sweat) glands
2/19/2009

15. Dermis
Lines of cleavage - “tension lines” in the skin indicate the predominant direction of underlying collagen fibers
Epidermal ridges reflect contours of the underlying dermal papillae and form the basis for fingerprints (and footprints); their function is to increase firmness of grip by increasing friction.
2/19/2009

16. 05_01bc
05_01bc

17. Basis of Skin Color
Variations in skin color arise from variations in the amounts of three pigments: melanin, carotene, and hemoglobin
Melanin - a yellow-red or brown-black pigment produced by melanocytes (located mostly in the epidermis, where it absorbs UV radiation)
The amount of melanin causes the skin’s color to vary from pale yellow to tan to black
The number of melanocytes are about the same in all people; differences in skin color is due to the amount of pigment produced
2/19/2009

18. Basis of Skin Color
A benign localized overgrowth of melanocytes is a nevus or mole
Albinism is an inherited inability to produce melanin - vitiligo is a condition in which there is a partial or complete loss of melanocytes in patches of skin
Carotene - yellow-orange pigment (found in the stratum corneum, dermis, and subcutaneous layer)
Hemoglobin - red color (located in erythrocytes flowing through dermal capillaries)
2/19/2009

19. A, B, C ’ s of Melanoma Asymmetry Borders Color Diameter Elevation
2/19/2009

20. 05_08
05_08

21. Subcutaneous Layer
Subcutaneous layer (hypodermis) is not part of the skin but, among its functions, it attaches the skin to the underlying tissues and organs; this layer (and sometimes the dermis) contains lamellated (pacinian) corpuscles which detect external pressure applied to the skin.
2/19/2009

22. Accessory Structures of the Skin: Objectives
Compare the structure and locations of sweat (sudoriferous), oil (sebaceous), ceruminous, and mammary glands. Also compare the composition and functions of their secretions.
Compare and contrast eccrine and apocrine glands.
List the functions of hair.
Describe the cause of acne and its treatments.
2/19/2009

23. Accessory Structures of the Skin
include hair, skin glands, and nails
Hairs (pili) have a number of important functions:
protection
reduction of heat loss
sensing light touch
Sebaceous (oil) glands are connected to hair follicles
2/19/2009

24. Skin Glands
Sebaceous glands secrete an oily substance called sebum which prevents dehydration of hair and skin, and inhibits growth of certain bacteria
Sudoriferous (sweat) glands – 2 types:
Eccrine sweat glands
Apocrine sweat glands
2/19/2009

25. 05_table_03
05_table_03

26. Acne Inflammation of sebaceous glands
Usually begins at puberty when sebaceous glands grow and increase production
Androgens play the greatest role
Due to colonization of glands by bacteria that grow and thrive in lipid-rich sebum
May cause a cyst of sac of connective tissue cells that can destroy and displace normal tissue with a scar
Treatment c/o benzoyl peroxide or tretinoin, antibiotics (tetracycline or erythromycin) and isotretinoin (accutane).
2/19/2009

27. Ceruminous and Mammary Glands
Modified sudoriferous (apocrine) sweat glands located in the ear canal and breast, respectively
Along with nearby sebaceous glands, ceruminous glands are involved in producing a waxy secretion called cerumen (earwax) which provides a sticky barrier that prevents entry of foreign bodies into the ear canal.
Mammary glands produce milk
2/19/2009

28. Types of Skin: Objectives
Compare and contrast structural and functional differences of thick and thin skin.
2/19/2009

29. 05_table_04
05_table_04

30. Functions of the Skin: Objectives
Describe how skin contributes to:
regulation of body temperature
blood reservoir
protection
cutaneous sensations
excretion and absorption
synthesis of vitamin D
2/19/2009

31. Functions of the Skin
regulation of body temperature: liberating sweat on its surface and adjusting flow of blood in the dermis.
blood reservoir: 8-10% of total blood flow in a resting adult
Protection: keratin barrier, lipids serve as barrier and resist dehydration, acid pH, pigment blocks UV, immunologic barrier
2/19/2009

32. Functions of the Skin
cutaneous sensations: touch, pressure, vibration, and tickling; pain
excretion and absorption: small role in excretion of wastes – ammonia and urea; absorption of water soluble substances is negligible, but some lipid soluble materials such as drugs and vitamins K, E, D, and A; steroids
synthesis of vitamin D: requires UV activation then converted to calcitriol in the kidneys
2/19/2009

33. Skin Wound Healing: Objectives
Explain epidermal and deep wound healing.
2/19/2009

34. Epidermal Wound Healing: superficial
2/19/2009

35. Deep wound healing: four phases
Inflammatory
Migratory
Proliferative
Maturation
Fibrosis – scar
Hypertrophic scar - keloid
2/19/2009

36. Deep Wound Healing
2/19/2009

37. Aging and the Integumentary System
Effects begins in late 40’s:
Wrinkling, loss of collagen and elastic tissue
decrease of skin’s immune responsiveness: Langerhans cells decrease and macrophages less effective
dehydration and cracking of the skin: decreased size of sebaceous glands
decreased sweat production
decreased numbers of functional melanocytes resulting in gray hair and atypical skin pigmentation
loss of subcutaneous fat
a general decrease in skin thickness
an increased susceptibility to pathological conditions: skin heals poorly, increased risk skin cancer and pressure sores develop more readily
growth of hair and nails decreases; nails may also become more brittle with age.
2/19/2009

38. Burns
Tissue damage from excessive heat, electricity, radioactivity, or corrosive chemicals that destroys (denatures) proteins in the exposed cells is called a burn.
Generally, the systemic effects of a burn are a greater threat to life than are the local effects.
Depending on the depth of damage, skin burns are classified as first-degree and second-degree (partial-thickness) and third-degree (full-thickness) (Figure 5.9)
The seriousness of a burn is determined by its depth, extent, and area involved, as well as the person’s age and general health. When the burn area exceeds 70%, over half of the victims die.
A method for determining the extent of a burn is the rule of nines method (Figure 5.10).
2/19/2009

39. Burns The injury of skin tissues results in severe systemic effects:
Large loss of water, plasma, and plasma proteins may result in shock
Risks of bacterial infections markedly increased
Reduced circulation of blood results
Decreased urine output
Markedly diminished immune responses
2/19/2009

40. 05_09
05_09

41. 05_10
05_10

42. End of Chapter 5 Copyright 2009 John Wiley & Sons, Inc
End of Chapter 5 Copyright 2009 John Wiley & Sons, Inc. All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein.
2/19/2009