Chapter 5: The Integumentary System

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1

Organs consist

Group of tissues that performs a specific function

2

System

Group of organs working together toward common goals

3

The organs that make up the integumentary system are

The skin and its derivatives, such as:

  • Hair
  • Nails
  • Glands
  • Nerve endings

Many interrelated factors affect both appearance and health of skin

4

The largest organ of the body

Skin

5

Dermatology

The medical specialty that deals with diagnosing and treating skin disorders

6

The skin consists of three principal parts

  • Epidermis--the outer, thinner portion, composed of epithelium
  • Dermis--the inner, thicker portion, composed of connective tissue
  • Subcutaneous (hypodermis)--superficial fascia--underlies from dermis
7

Functions of skin

  • Regulate body temperature
  • Protection (Ex. Burns)
  • Sensation (Ex. Pain)
  • Excretion (Ex. Sweat)
  • Immunity (Ex. Mechanical barrier)
  • Blood reservoir (Ex. Blood vessels stored in skin)
  • Synthesis of vitamin D (Ex. Sunlight, consumption of milk)
8

Epidermis

Composed of stratified squamous epithelium

9

Epidermis contains four principle types of cells

  • Keratinocytes
  • Melanocytes
  • Langerhans cells
  • Merkel cells
10

Four or five (palm and sole) distinct layers of cells form the epidermis

  • Stratum basale (stratum germinativum)
  • Stratum spinosum
  • Stratum granulosum
  • Stratum lucidum (only palms and soles)
  • Stratum corneum
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Basale layer undergoes

Continuous cell division and produces all other layers

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The cells in the multiple layers of the stratum corneum are

Continuously shed and replaced by cells from deeper strata

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Keratinization

Replacement of cell contents with the protein keratin, occurs as cells move to the skin surface over 2-4 weeks

14

Epidermal growth factor (EGF)

Hormone that stimulates growth of epithelial and epidermal cells during tissue development, repair, and renewal

15

Dermis

Composed of connective tissue containing collagen and elastic fibers and has two regions

16

The two regions of the dermis

  • Papillary layer
  • Reticular layer
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The papillary layer

Areolar connective tissue containing fine elastic fibers, dermal papillae, and corpuscle of touch (Meissner's corpuscles)

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The reticular layer

Irregular connective tissue containing collagen and elastic fibers, adipose tissue, hair follicles, nerve, sebaceous (oil) glands, and ducts of sudoriferous (sweat) glands

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Strength, extensibility, and alasticity are provided to the skin by the combination of

Collagen and elastin fibers

20

Lamellated or Pacinian, corpuscles are found

Subcutaneous layer (hypodermis, or superficial fascia)

21

Lines of cleavage (tension lines)

Indicate the direction of collagen fiber bundles in the dermis and are considered in making surgical incisions

22

Variety of colors in the skin is due to three pigments

  • Melanin
  • Carotene
  • Hemoglobin (in blood capillaries) - in the dermis
23

The color of skin and mucous membranes can provide clues for diagnosing certain problems

  • Cyanosis
  • Jaundice
  • Erythema
24

Cyanosis is seen

Respiratory and

25

Jaundice (liver disfunction) is seen

Yellowing of sclera of eyes and can be cured by UV radioactive light or sunglight

26

Erythema is seen

Superficial reddening of the skin, usually in patches, as a result of injury or irritation causing dilation of blood capillaries

27

Epidermal ridges

Increase friction for better grasping ability and provide the basis for fingerprints and footprints. The ridges typically reflect contours of the underlying dermis

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The cause for epidermal ridges

The blood pressure in the capillary beds in the papillae

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When the germinal portion of the epidermis is destroyed

New skin cannot regenerate without a skin graft

30

Skin graft is most successful when it comes from

The individual himself or from an identical twin

31

Another type of self-donation in which sheets of skin are grown in the laboratory from a small amount of the patient's epidermis; synthetic material may be used to simulate dermis and epidermis while the skin is being grown

While the skin is being grown in laboratory, a temporary donor (recently deceased--48 hours) skin needs to be a minimum of 70%

Autologous skin transplantation

32

Epidermal derivatives

Structures developed from the embryonic epidermis such as:

  • Hair
  • Skin glands (sebaceous, sudorifous, and ceruminous)
  • Nails
33

Hair or pilli

  • Epidermal growths that function in protection and reduction in heat loss
  • Consist of a shaft above the surface, a root that penetrates the dermis and subcutaneous layer, and a hair follicle
  • Associate with hairs are sebaceous (oil) glands, arrectores pilorum muscles, and root plexuses
  • New hairs develop from cell division of the matrix in the bulb; hair replacement and growth occur in a cyclic pattern
  • Color is primarily due to melanin (black, brown, red, blonde)
  • Hormones (androgens) can stimulate growth in males and females or somehow inhibit it in genetically predisposed males (male-pattern baldness)--Drug treatment
34

Three types of glands

  • Sebacous (oil) glands
  • Sudoriferous (sweat) gland
  • Ceruminous glands
35

Sebacous (oil) glands

Usually connected to hair follicles; they are absent in the palms and soles

  • Produce sebum, which moisten hairs, waterproofs and softens the skin, and inhibits bacterial growth
  • Enlarged glands may produce blackheads, pimples, and boils
36

Sudoriferous (sweat) gland

Divided into apocrine and eccrine types

  • Eccrine sweat glands have an extensive distribution; their ducts terminate at pores at the surface of the epidermis
  • Apocrine sweat glands are limited in distribution to the skin of the axilia, pubis, and areolae; their ducts open into hair follicle to drain
  • Produce perspiration (sweat), which assists in maintaining body temperature and also carries small amounts of wastes to the surface
37

Ceruminous gland

Modified sudoriferous glands that produce a waxy substance called cerumen. They are found in the external auditory meatus

38

Some effective ways to remove earwax

  • Candle
  • Hydrogen peroxide
  • Q-tips
  • Leave it alone; it falls out within 7-10 days
39

Nails

Hard, keratinized epidermal cells over the dorsal surfaces of the terinal portions of the fingers and toes

  • Principal parts of a nail are the body, free edge, root, lunula, eponychium, and matrix
  • Cell division of the matrix cells produce new nails
  • Help grasping and manipulating small objects in various ways and provide protection against trauma to the ends of the digits
40

Epidermal wound examples

  • Abrasions
  • First degree or second degree burns
41

Epidermal wound healing

  • Central portion of the would usually extends deep down to the dermis, wheras the wound edges usually involve only superficial damage to the epidermal cells
  • Repaired by enlargement and migration of basal cells, contact inhibition, and division of migrating and stationary basal cells
42

Deep wound healing

  • When an injury extends to tissues deep to the epidermis, the repair process is more complex then epidermal healing, and scar formation results
  • Inflammatory phase, blood clot unites the wound edges, epithelial cells migrate across the wound, vasodilation and increased permeability of blood vessels deliver phagocytes, and fibroblasts form
  • Migratory phase, epithelial cells beneath the scab bridge the wound, fibroblasts begin to synthesize scar tissue, and damaged blood vessels being to grow. During this phase, tissue filling the wound is called granulation tissue
  • Proliferative phase, the events of the migratory phase intensify
  • Maturation phase, the scab sloughs off, the epidermis is restored to normal thickness, collagen fibers become more organized, fibroblasts begin to disappear, and blood vessels are restored to normal
43

Thermoregulation

Homeostasis of body temperature

44

Normal body temperature

37oC (98.6oF)

45

If environment temperature is high,

Skin receptors sense the stimulus (heat) and generate impulses (input) that are transmitted to the brain (control center). The brain then sends impulses (output) to sweat glands (effectors) to produce perspiration. As the perspiration evaporates, the skin is cooled and body temperature returns to normal

46

The skin-cooling response is

Negative feedback mechanism

47

Temperature maintenance is also accomplished by

Adjusting blood flow to the skin

48

Most effects of aging of the skin

Do not occur until and individual reaches the late forties

49

Among the effects of aging on the integument are

Wrinkling, slower growth of hair and nails, dryness and cracking due to sebaceous gland atrophy, decrease in number of melanocytes (gray hair, blotching) and Langerhans cells (decreased immune responsiveness) and loss of subcutaneous fat (thinner skin)

50

Chronic ultraviolet exposure

Accelerates skin aging and greatly increases skin cancer risk

51

The epidermis is derived from

Ectoderm

52

The dermis is derived from

Wandering mesenchymal cells

53

Tissue damage from excessive heat, electricity, radioactivity, or corrosive chemicals that destroys (denatures) proteins in the exposed cells

Burn

54

Systemic effects of a burn are a greater threat to life thean

The local effects

55

Depending on the depth of damage, skin burns are classified as

First-degree and second-degree and third-degree burns

56

First-degree and second-degree burn

Partial thickness

57

Third-degree burn

Full-thickness

58

The seriousness of a burn

Determined by its depth, extent, and area involved, as well as the person's age and general health.

59

Over half of the victims die when

Burn area exceeds 70%

60

Two methods for determining the extent of a burn are

  • The rule of nines (based on body surface)
  • The Lund-Browder (based on age) method
61

Sunburn

Injury to the skin as a result of acute overexposure to the UV rays in sunlight

62

Skin cancer

Caused by excessive exposure to sunlight

63

Three most common forms are

  • Basal cell carcinoma (BCC)
  • Squamous cell carcinoma (SCC)
  • Malignant melanoma
64

Among the risk factors for skin cancer are

  • Skin type
  • Sun exposure
  • Family history
  • Age
  • Immunologic status
65

Acne

Inflammation of sebaceous glands that usually begin at puberty under the influence of androgens

66

Pressure sores

Also known as, decubitus ulcers are caused by a constant deficiency of blood tissue overlying a bony projection that has been subjected to prolonged pressure against an object such as a bed, cast, or splint; the deficiency results in tissue ulceration