1. Objectives To explain the function of the integumentary system.
To identify the components of the epidermis.
To list the strata of the epidermis.

2. Definitions Epi – upon, on top of Hypo – under Derm – skin
Serous membrane – membranes that line the body cavities
Mucous membrane – membranes that open to the outside of the body
Synovial membrane – Membranes in our joints

3. The Integumentary System: An Overview

4. Introduction
Organs are body structures composed of two or more different tissues.
The skin and its accessory organs make up the integumentary system

5. Parts of the integumentary system
Skin – largest organ in our body
Body membranes
Hair
Nails

6. Functions: Protective covering
Helps regulate body temperature (homeostasis)
Prevents water loss from deeper tissues
Houses sensory receptors
Synthesizes biochemicals
Excretes small quantities of waste

7. Consists of… Cutaneous membrane
Epidermis – Outermost layer
Dermis – Middle layer
Accessory structures- hair, sweat glands, sebaceous glands etc.
Subcutaneous layer (hypodermis) – innermost layer

8. Components
Figure 5.1

9. Cutaneous Membrane Cutaneous membrane is another word for skin.
Dry membrane
Act as protective covering from….
Mechanical damage (bumps)
Chemical damage (acids and bases)
Bacterial damage
UV radiation
Thermal damage
Desiccation (drying out)

10. Cutaneous Membrane Regulate body temperature Prevent water loss
House sensory receptors
Send signals to your brain about what you can feel
Synthesize various biochemicals
Like Vitamin D

11. 3 Layers of Cutaneous Membrane
Epidermis:
Structure: Top layer; stratified squamous tissue
Function: protection
Dermis:
Structure: middle layer, largest layer. Hair, sweat glands, nails, oil glands
Hypodermis:
Structure: Bottom layer. Loose connective tissue and adipose tissue.
Function: Insulation, houses major blood vessels.

12. The Epidermis

13. Thin Skin and Thick Skin
The epidermis is composed of layers of keratinocytes- cells that produce keratin
Thin skin = four layers (strata)
Thick skin = five layers
Figure 5.2

14. The Epidermis Composed of stratified squamous epithelium
Lacks blood vessels
Older cells are pushed to the top and harden in a process called keratinization.

15. Layers of the epidermis:
From deep…….
Stratum basale/ germinativum (cells undergoing mitosis)
Stratum spinosum
Stratum granulosum
Stratum lucidum (only occurs in thick, hairless skin of palms and hands and soles of feet)
Stratum corneum (cells filled with keratin to protect and prevent water loss from skin)
…… to superficial

16. The Structure of the Epidermis
Figure 5.4

17. Epidermis Cell Layers Germinative Spinosum- spiny layer
Basal cells (stem) are reproducing
Spinosum- spiny layer
Granulosum- grainy layer
Stops dividing, start producing keratin
Lucidum
The clear layer found only in thick skin
Corneum
Exposed to surface and shed every 2 wks.

18. Skin color depends on… Genetics Blood supply Carotene Melanin
Differing amounts of melanin and size of melanin granules
Blood supply
Interrupted blood supply leads to cyanosis- blue!
Carotene
Orange-yellow pigment found in orange vegetables
Melanin
Yellow-brown pigment
Protects deeper cells from UV radiation
Produced by melanocytes

19. Melanocytes
Figure 5.5a, b

20. Epidermal cells
Synthesize vitamin D3 (cholecalciferol) when exposed to UV
Aids in absorption of calcium and phosphorus- needed for bone strength
Respond to epidermal growth factor
Growth
Division
Repair
Secretion

21. Objectives The explain the components of the dermis.
To understand why tattoos are permanent.
To identify accessory organs of the integument and explain their function.

22. The Dermis

23. Dermal Organization Located between epidermis and subcutaneous layer
Consists of connective tissue with collagen and elastic fibers within a gel-like substance
Anchors accessory structures- hair follicles, sweat glands, blood vessels etc.
Carry nutrients to upper layers of skin and help regulate temperature.
Two components:
Outer papillary layer
Deep reticular layer

24. Layers of the Dermis Papillary layer Reticular layer Areolar tissue
Contains blood vessels, lymphatics, sensory nerves of epidermis
Reticular layer
Dense irregular connetive tissue
Contains network of collagen and elastic fibers to resist tension

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

27. Lines of Cleavage of the Skin
Figure 5.7

28. Hypodermis (subcutaneous)
Elastic areolar tissue and adipose tissue
Stabilizes skins position against underlying organs and tissues
Shock absorber and insulator
Few capillaries and no vital organs
Subcutaneous injection is useful to administer drugs

29. Structures Hair papilla Root Shaft
Connective tissue containing capillaries and nerves
Root
Anchors hair into skin
Shaft
Part we see on the surface
Consists of three layers
Cuticle- overlapping shingle layer
Cortex- underlying layer- pigments
Medulla- core of hair

30. Structures Contd. Sebaceous Glands Arrector pili muscle
Also called holocrine glands
Associated with hair follicles
Discharge oily substance into hair follicles (waterproofs and moisturizes the hair shafts)
Inhibits growth of bacteria
Activated at puberty
Arrector pili muscle
Pulls on follicle, forcing the hair to stand up
Cold or emotional states- goosebumps

31. Anatomy of a Single Hair
Figure 5.9

32. Hair Follicles and Hair

33. Hair Follicles
Figure 5.10a-c

34. Hair

35. Hairs
Individual hairs develop from cells at the base of the hair follicle, an invagination of the lower epidermis that dips down into the dermis.
As new cells are formed, old cells are pushed outward and become keratinized, forming the hair shaft.
Project deep into the dermis and often into the hypodermis

36. Hair Color Melanin produced by melanocytes at the hair papilla
Red hair also contains the pigment trichosiderin
Determined by genetics

37. Function of Hair Head Nostrils, ears, and eyes Sensory
Protection from UV light
Cushion a light blow to head
Insulation
Nostrils, ears, and eyes
Prevent entry of particles
Sensory
Sensory nerve fiber at base of every hair

38. Appendages of the Skin

39. Appendages of the Skin

40. Exocrine Glands- Reach Outside
Sebaceous glands (Oil glands)
Associated with hair
Secrete sebum, which lubricates and inhibits bacteria growth
Acne- condition when they are clogged
Sweat glands (Watery Glands)
2 kinds
Eccrine: all over the body
Apocrine: armpits and groin (hormonal)

41. Sweat Glands
Eccrine – respond to body temperature; open via duct to pore on skin surface
Apocrine – responds to body temperature, stress; ducts empty into hair follicles
Ceruminous glands – modified sweat glands that secrete wax in the ear canal
Mammary glands – modified type of sweat glands that secrete milk

42. Sebaceous Glands and Hair
Figure 5.11

43. Sweat Glands

44. Figure Sweat Glands
Figure 5.12a, b

45. Sweat and Its Function Composition: Function:
Mostly water
Salts and vitamin C
Some metabolic waste
Fatty acids and proteins (apocrine only)
Function:
Helps dissipate excess heat
Excretes waste products
Acidic nature inhibits bacteria growth
Odor is from associated bacteria

46. Regulation of body temperature
Heat may be lost to surroundings from the skin.
Body responds to excessive heat by dilation of dermal blood vessels and sweating.
Body responds to excessive cooling by constricting dermal blood vessels, inactivation sweat glands and shivering.

47. Nails Keratinized cells that protects the tips of fingers and toes
Stratified squamous overlying the nail bed
Lunula is the most actively growing region of the nail root

48. Structures Nail Body Nail Root Cuticle
Covers an area of the epidermis called the nail bed
Nail Root
Where nail production occurs
Not visible on surface
Cuticle
Portion of stratum corneum

49. Structure Contd. Lunula
Pale crescent area near the root were blood vessels are absent

50. Figure 5.13 The Structure of a Nail

51. Loss of Homeostasis in Skin

52. Skin Homeostatic Imablance
Infections
Athlete’s foot (tinea pedis) – fungal infection
Boils and carbuncles – bacterial infection
Cold sores – caused by virus

53. Skin Homeostatic Imbalance

54. Skin Homeostatic Imabalance
Burns
Tissue damage and cell death caused by heat, electricity, radiation, or chemicals
Associated dangers
Dehydration
Electrolyte imbalance
Circulatory shock

55. Severity of Burns First-degree burns Second-degree burns
Only epidermis is damaged
Skin is red and swollen
Second-degree burns
Epidermis and upper dermis are damaged
Skin is red with blisters
Third-degree burns
Destroys entire skin layer
Burn is gray-white or black

56. Severity of Burns

57. Critical Burns Burns are considered critical if
Over 25% of the body has second-degree burns
Over 10% of the body has third-degree burns
There are third-degree burns on the face, hands, or feet

59. Healing of Wounds
Inflammation – blood vessels dilate and become more permeable
Causes tissues to become red and swollen
This is the body’s normal response to injury
Superficial cuts are filled in by reproducing epithelial cells
Deeper cuts are closed off by clots, covered by scabs and eventually filled in by fibroblasts, making connective tissue.
Blood vessels extend into the area, the injured tissues are replaced, and the scab falls off.
Large wounds leave scars and helping may be accompanied by the formation of granulations.

62. Skin Cancer
Cancer – unregulated mitotic cell division producing abnormal mass
Classified in two ways
Benign – does not spread
Malignant – metastasized (moves) to other parts of the body
Skin cancer is the most common type of cancer!!

63. Basal Cell Carcinoma Least malignant Most common type
Arises from stratum basale

64. Squamous Cell Carcinoma
Metastasizes to lymph nodes if not removed
Early removal allows a good chance of cure
Believed to be sun-induced
Arises from stratum spinosum

65. Malignant melanoma Most deadly of skin cancers Caner of melanocytes
Metastasizes rapidly to lymph and blood vessels
Detection uses ABCD rule

66. ABCD rule A = Asymmetry B = Border irregularity C = Color D = Diameter
Two sides of pigmented mole do not match
B = Border irregularity
Borders of mole are not smooth
C = Color
Different colors in pigmented area
D = Diameter
Spot is lager than 6 mm in diameter

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The Skeletal System
The Skeletal System
provides structural support
The Integumentary System synthesizes vitamin D3, essential for calcium and phosphorus absorption (bone maintenance and growth)
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The Muscular System
The Muscular System’s facial muscles pull against skin of face, producing expressions important in communication
The Integumentary System synthesizes vitamin D3 , essential for normal calcium absorption (calcium ions play an essential role in muscle contraction)
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The Nervous System
The Nervous System controls blood flow and sweat gland activity for thermoregulation; stimulates contraction of arrector pili muscles to elevate hairs
The Intergumentary System’s receptors in dermis and deep epidermis provide sensations of touch, pressure, vibration, temperature, and pain
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The Endocrine System
The Endocrine System includes the sex hormones that stimulate sebaceous and apocrine gland activity, and develop secondary sexual characteristics; suprarenal hormones alter blood flow to skin and mobilize lipids from fat cells
The Integumentary System synthesizes vitamin D3, precursor of calcitriol, a hormone produced by the kidneys
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71. The Cardiovascular System
The Cardiovascular System provides oxygen and nutrients; delivers hormones and cells of immune system; carries away carbon dioxide, waste products, and toxins; provides heat to maintain normal skin temperature
The Integumentary System’s mast cells produce localized changes in blood flow and capillary permeability
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The Lymphatic System
The Lymphoid System assists in defending the integument by providing additional macrophages and mobilizing lymphocytes
The Integumentary System provides physical barriers that prevent pathogen entry; macrophages resist infection; mast cells trigger inflammation and initiate the immune reponse
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73. The Respiratory System
The Respiratory System provides oxygen and eliminates carbon dioxide
The Integumentary System’s hairs guard entrance to nasal cavity
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The Digestive System
The Digestive System Provides nutrients for all cells and lipids for storage by adipocytes
The Integumentary System synthesizes vitamin D3, needed for absorption of calcium and phosphorus
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The Urinary System
The Urinary System excretes waste products, maintains normal body fluid pH and ion composition
The Integumentary System assists in elimination of water and solutes; keratinized epidermis limits fluid loss through skin
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