2. The Integumentary System
Integument is skin
Skin and its appendages make up the integumentary system
Two distinct layers
Epidermis
Dermis

3. The Integumentary System
Epidermis - outer layer
Dermis – inner layer
Sweat glands:
excrete sweat through pores
Sweat is made up of urea, salts, and water
Largest organ of the body.
It’s the body’s first line of defense

4. The “Birthday Suit” Combination of 4 main tissues:
Epithelial – outer layer
Connective – underlies dermis
Smooth Muscle – goose bumps
Nervous – sensory receptors

5. Functions of the Skin Protection
Acts as cushion, insulator, waterproofing
Protects from chemicals, heat, cold, bacteria
Screens UV
Temperature regulation and sensory receptor (nerve endings)
Storage of chemical compounds
Excretion and secretion
Synthesis and storage of nutrients

6. The Skin FG04_02.JPG Title: Components of the Integumentary System
Notes: Relationships among the major components of the integumentary system (with the exception of nails, shown in Figure 4-15).
Keywords: integumentary system, cutaneous, epidermis, dermis, papillary layer, reticular layer, hair follicles, exocrine glands, nails

7. Epidermis Outer layer of dead skin cells called cuticle
Layer you see everyday
“Ashiness” is caused by this layer of dead skin cells being very rough
DUST you see around is made up of dead skin cells!
Under the cuticle is another layer of living epithelial cells that make up the rest of the epidermis.

8. Epidermis Four types of cells Layers (from deep to superficial)
Keratinocytes – deepest, produce keratin (tough fibrous protein)
Melanocytes - make dark skin pigment melanin
Merkel cells – associated with sensory nerve endings
Langerhans cells – macrophage-like dendritic cells
Layers (from deep to superficial)
Stratum basale or germinativum – single row of cells attached to dermis; youngest cells
Stratum spinosum – spinyness is artifactual; tonofilaments (bundles of protein) resist tension
Stratum granulosum – layers of flattened keratinocytes producing keratin (hair and nails made of it also)
Stratum lucidum (only on palms and soles)
Stratum corneum – horny layer (cells dead, many layers thick)

9. Epithelium: layers (on left) and cell types (on right)

10. Remember… Four basic types of tissue
Epithelium – epidermis just discussed
Connective tissue - dermis
Muscle tissue
Nervous tissue

11. Epidermis and Dermis Epidermis is avascular (no blood vessels)
Dermis is highly vascular (has blood vessels)
Epidermis receives nourishment from dermis
Cells far away from nourishment die

12. Epidermis FG04_03.JPG Title: The Structure of the Epidermis
Notes: A light micrograph through a portion of the epidermis, shows the major stratified layers of epidermal cells.
Keywords: epidermis, structure, layers, stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, stratum germinativum, dermis

13. Dermis Thick layer under the epidermis
Strong, flexible connective tissue: your “hide”
Rich supply of nerves and vessels
Critical role in temperature regulation

14. Deeper Layer of the Dermis
Contains
Blood vessels
Glands
Deep pressure receptors
Attached to underlying organs by the subcutaneous layer
Packed with adipose cells
Stabilizes position of skin

15. Dermal Components Communication with other organ systems
Cardiovascular
Lymphatic
Nervous
Sensation
Control of blood flow and secretion

16. Epidermis and dermis of (a) thick skin and (b) thin skin
(which one makes the difference?)

17. Fingerprints
Human Anatomy, 3rd edition
Prentice Hall, © 2001

18. Fingerprints, palmprints, footprints
Dermal layer lie atop dermal ridges
Elevate the overlying epidermis into epidermal ridges
“Prints” are actually “sweat films” because of sweat pores
Genetically determined
Flexion creases
Deep dermis, from continual folding
Fibers
Collagen: strength and resilience
Elastic fibers: stretch-recoil
Striae: stretch marks
Tension lines (or lines of cleavage)
The direction the bundles
of fibers are directed
The dermis is the receptive site for the pigment of tattoos

19. Skin Color Three skin pigments
Melanin: the most important
Carotene: from carrots and yellow vegies
Hemoglobin: the pink of light skin
Melanin in granules passes from melanocytes (same number in all races) to keratinocytes in stratum basale
Digested by lysosomes
Variations in color

20. Skin Appendages Derived from epidermis but extend into dermis Include
Hair and hair follicles
Sebaceous (oil) glands
Sweat (sudoiferous) glands
Nails

22. What Else Comes from the Epidermis?
Nails
Hair
Glands

23. Nails Made of hard keratin Corresponds to hooves and claws
Grows from nail matrix

24. Nail Structure
Nail body
Free edge
Nail root
Matrix
Lunula (moon)

25. Nail Structure FG04_15.JPG Title: Structure of a Nail
Notes: These drawings illustrate the prominent features of a typical fingernail as view from the surface and in section.
Keywords: fingernail, hyponychium, nail bed, lateral nail groove, lunula, eponychium, phalanx, dermis, epidermis

26. Functions of Hair Protection Thermoregulation
scalp
Thermoregulation
less in humans than other mammals
Sensory
sense light touch of the skin
Minor role in humans

27. Hair growth: averages 2 mm/week Hair loss Hair color
Types of hair
Vellus: fine, short hairs
Intermediate hairs
Terminal: longer, courser hair
Hair growth: averages 2 mm/week
Active: growing
Resting phase, then shed
Hair loss
Thinning – age related
Male pattern baldness
Hair color
Amount of melanin for black or brown; distinct form of melanin for red
White: decreased melanin and air bubbles in the medulla
Genetically determined though influenced by hormones and environment

28. Hair Structure Shaft Superficial portion Root Below the surface
Cuticle
Outermost layer of hair
Hair develops in follicles
Downward continuation of epidermis

29. Hair Structure FG04_10A.JPG Title: Hair Follicles
Notes: Hairs originate in complex organs termed follicles. (a) A longitudinal section and a cross section through a hair follicle. (b) and (c) A section along the longitudinal axis of a hair follicle.
Keywords: hair follicle, longitudinal section, cross section, sebaceous gland, arrectory pili muscle, cortex, cuticle, internal root sheath, connective tissue layer, glassy membrane, external root shaft

30. Growth of Hair Contains melanocytes Hair papilla Bulb
At the base of the follicle
Contains blood vessels and nerves
Nourishes hair
Bulb
Contains matrix – epithelial cells responsible for growth
Contains melanocytes

31. Arrector Pili Smooth muscle attaches to follicle Raises hairs
Response to fright or cold
Function?

32. *“arrector pili” is smooth muscle *
Hair and hair follicles: complex Derived from epidermis and dermis Everywhere but palms, soles, nipples, parts of genitalia
*“arrector pili” is smooth muscle *
Hair bulb: epithelial cells surrounding papilla
Hair papilla
is connective tissue________________

33. Glands Sebaceous glands Connected to hair follicles
Secrete a waxy, oily substance (sebum)
Blackheads
Secretion increases at puberty

34. Sebaceous (oil) glands
Entire body except palms and soles
Oils and lubricates

35. Other Glands Sweat Glands Found just about everywhere
Produce “perspiration”
Water, salt, metabolic wastes
Function – cooling of the body
Scent Glands
Specific type of sweat gland
Found near hair follicles
Axillary & genital regions
Develop at puberty

36. Sweat Glands Prevent overheating 500 cc to 12 l/day! (is mostly water)
Humans most efficient (only mammals have)
Produced in response to stress as well as heat

37. Types of Sweat Glands Eccrine or merocrine Apocrine
Most numerous
True sweat: 99% water, some salts, traces of waste
Open through pores
Apocrine
Axillary, anal and genital areas only
Ducts open into hair follicles
The organic molecules in it decompose with time - odor
Modified apocrine glands
Ceruminous – secrete earwax
Mammary – secrete milk

38. The skin also helps control body temperature- Homeostasis
When you sweat, heat leaves the body through your pores.
When the sweat hits the outer surface of the skin, it is cooled by the air.
This lowers your body temperature.

39. The Skin with Sweat Glands
FG04_02.JPG
Title: Components of the Integumentary System
Notes: Relationships among the major components of the integumentary system (with the exception of nails, shown in Figure 4-15).
Keywords: integumentary system, cutaneous, epidermis, dermis, papillary layer, reticular layer, hair follicles, exocrine glands, nails

40. Diseases and Disorders of the Integumentary System

41. Skin Injury and Repair
Bleeding occurs at the site of injury immediately after the injury, and mast cells in the region trigger an inflammatory response.
Epidermis
Dermis
After several hours, a scab has formed and cells of the stratum germinativum are migrating along the edges of the wound. Phagocytic cells are removing debris, and more of these cells are arriving with the enhanced circulation
in the area. Clotting around the edges
of the affected area partially isolates
the region.
Sweat
gland
Scab
Macrophages
and
fibroblasts
Migratory
epithelial
cells
Granulation
tissue

42. Skin Injury and Repair
One week after the injury, the scab has been undermined by epidermal cells migrating over the meshwork produced by fibroblast activity. Phagocytic activity around the site has almost ended, and the fibrin clot is disintegrating.
Fibroblasts
After several weeks, the scab has been shed, and the epidermis is complete. A shallow depression marks the injury site, but fibroblasts in the dermis continue to create scar tissue that will gradually elevate the overlying epidermis.
Scar
tissue

43. Aging of the Skin Major Age-Related Changes
Injury and infection increase
Immune cells decrease
Sun protection diminishes
Skin becomes dry, scaly
Hair thins, grays
Sagging, wrinkles occur
Heat loss decreases
Repair slows

44. Effects of UV Radiation
Beneficial effect - activates synthesis of vitamin D3
Harmful effects
Sun burn
Wrinkles, premature aging
Malignant melanoma
Basal cell carcinoma

45. Types and Growth of Hair
Vellus hairs
Body hairs of women and children
Terminal hairs
Hair of scalp
Axillary and pubic area (at puberty)
Hair thinning and baldness
Due to aging
Male pattern baldness

46. Burns Threat to life Catastrophic loss of body fluids
Dehydration and fatal circulatory shock
Infection

47. Burns Classified by severity Infections Skin cancer
First-degree burn – only upper epidermis is damaged - redness (e.g. sunburn)
Second-degree burn – upper part of dermis is also damaged
Blisters appear
Skin heals with little scarring
Third-degree burn
Consume thickness of skin
Burned area appears white, red, or blackened
Can lead to
Infections
Skin cancer

48. Skin Injury and Repair
Table 5-1

49. First-degree Second-degree Third-degree (epidermis only; redness)
(epidermis and dermis,
with blistering)
Third-degree
(full thickness, destroying epidermis, dermis, often part of hypodermis)

50. Critical burns Over 10% of the body has third-degree burns
25 % of the body has second-degree burns
Third-degree burns on face, hands, or feet

51. Skin Cancer Basal cell carcinoma Squamous cell carcinoma Melanoma
Least malignant and most common
Squamous cell carcinoma
Arises from keratinocytes of stratum spinosum
Melanoma
A cancer of melanocytes
The most dangerous type of skin cancer

52. Tumors of the skin Benign, e.g. warts
Cancer – associated with UV exposure (also skin aging)
Aktinic keratosis - premalignant
Basal cell - cells of stratum basale
Squamous cell - keratinocytes
Melanoma – melanocytes: most dangerous; recognition:
A - Asymmetry
B - Border irregularity
C - Colors
D - Diameter larger than 6 mm

53. Skin Cancer Squamous cell carcinoma Basal cell carcinoma Melanoma
Figure 5.12

54. Use the following vocabulary to label the diagram: hair shaft, oil (sebaceous)gland, fat cells, erector pili muscle, blood vessels, nerve endings, epidermis, dermis, cuticle, epithelial cells, hair follicle, sweat gland, connective tissue