1. Integumentary System Integumentary System consists of the
Skin and its accessory organs

2. The skin may not typically be thought of as an organ, but it is made of tissues that work together as a single structure to perform unique and critical functions

3. Functions of the Integumentary System
Protection
Temperature regulation
Sensations
Storage of chemical compounds
Excretion of wastes
Synthesis of compounds (Vitamin D3)

4. The skin is made of multiple layers of cells and tissues, which are held to underlying structures by connective tissue
Epidermis
Dermis
Hypodermis

5. Epidermis
Lacks blood vessels (avascular)- gets all nutrients from blood supply in dermis
Composed of:
Stratified squamous epithelium
Contains:
the skin pigment Melanin

6. Dermis Thicker than the epidermis Composed of: Contains:
Nervous Tissue
Connective Tissue
Muscle Tissue
Epithelial Tissue
Contains:
Blood Vessels
Touch receptors
Accessory Organs

7. Dermis Contains Vasculature
Provides blood supply/nutrients to all skin cells
Plays role in thermo-regulation (vaso dialation/constriction)

8. The dermis contains many different touch receptors
The dermis contains many different touch receptors. Different types of touch have different receptors.

9. Separates the epidermis and dermis
Basement Membrane
Separates the epidermis and dermis

10. Image shows cancer cell (green) crossing the basement membrane (red)
Significance in health:
The basement membrane must be broken down in order for cancer cells to invade surrounding tissue.
Image shows cancer cell (green) crossing the basement membrane (red)

11. Hypodermis

12. Hypodermis Binds the skin to the underlying organs Composed of:
loose connective tissue
adipose tissues
Contains:
Major blood vessels

13. Burn classification based upon what layer(s) of tissue have been damaged

14. Epidermis Contains 5 layers!
We are only concerned with 2 in this class
ALIVE!
Stratum Basale – Inner most layer Location of actively dividing epithelial cells and melanocytes
DEAD!
Stratum Corneum – Outer most layer Dead cells serve as protective barrier

15. Colored scanning electron micrograph (SEM) of human skin
Stratum Corneum
Stratum Basale
Dermis

16. Keratin is a type of fibrous structural proteins.
Keratinization
Cells divide in Stratum Basale and push older cells up to surface.
Cells starve and die as pushed away from dermis.
Keratinization is the hardening process these cells undergo as they die.
Keratin is a type of fibrous structural proteins.

17. The surface of your skin!

19. Keratinization
Keratinization- the cementing of keratin fibers(cytoskeleton protein) in the dead cells.
Constant shedding and replacement grows new EPIdermis every days
Calluses- Thickening of the Stratum Corneum due to rubbing and pressure

20. Calluses

21. Accessory Structures of the Skin

22. Melanin
A dark pigment produced by melanocytes.

23. Vitiligo 

24. Melanocytes are located in the bottom layer of the epidermis

25. Why do you think a tan fades?

26. Melanin Absorbs UV radiation which protects the deeper tissues
Tanning and dark skin color comes from melanocytes producing more melanin
NOT due to more melanocytes

27. Hair Found on most skin surfaces Functions: Prevent heat loss
Exceptions:
Palms
Soles of feet,
Lips
Nipples
Parts of the genitalia
Functions:
Prevent heat loss
Decrease sun exposure
Touch receptors

28. Hair is a keratinous filament growing out of the epidermis
Hair is a keratinous filament growing out of the epidermis. It is primarily made of dead, keratinized cells.

29. Hair follicles Follicles are the hair producing structures.
Extend from the surface into the dermis
Each hair develops from STRATUM BASALE cells in the base of the hair follicle
Cells undergo keratinization and form into hair rather than a layer like skin

31. Arrector pili muscle- bundle of smooth muscle attached to each hair follicle
-When the muscle contracts, hair within the follicle tends to stand on end
-Emotional upset and cold can stimulate the arrector pili muscles to contract causing goose bumps

33. DON’T WORRY ABOUT ALL THIS!
Just showing that hair is actually pretty complicated…

34. Nails Protective coverings
Composed of keratinized stratified squamous epithelial cells.
Arise from the epidermis.
Look familiar?

35. Nails
The nail forms at the nail root, which has a matrix of proliferating cells from the stratum basale that enables the nail to grow continuously

36. Nails
As the nail develops, it slides forward over a layer of epithelium called the nail bed to which the nail remains attached

37. The nail bed is rich in blood vessels, making it appear pink, except at the base, where a thick layer of epithelium over the nail matrix forms a crescent-shaped region called the lunula (the “little moon”).

38. Sebacous Glands- produce an oil secretion called sebum
A mixture of fatty material and cellular debris, secreted into the hair follicles
Function:
Helps keep the hair and skin soft, pliable and relatively waterproof.

39. Sudoriferous glands (sweat glands)
Sweat is mostly water with small amounts of salt, urea and uric acid
Location:
Nearly all regions of the skin, most numerous in the palms and soles
Located in deeper dermis or superficial subcutaneous layer.
Structure:
Gland consists of tiny tube (duct) that originates as a ball-shaped coil closed at its deepest end
Coiled duct lined with sweat secreting epithelial cells
Duct opens at the surface as a pore

40. Sudoriferous glands
Two Types of Sudoriferous Glands:
Apocrine
Eccrine

41. Apocrine Eccrine Respond to:
Emotional stress (emotionally upset, frightened or experiencing pain)
Location:
Numerous in the armpits and groin
Development:
Glands development stimulated by sex hormones
Begin to function as an individual becomes sexually mature (puberty)
Eccrine
Elevated body temperatures
Entire body
Functional from birth

42. Sweat Glands- Eccrine and Apocrine
Axillary, and pubic areas only.
Develop during puberty
Do not regulate body temp.
Activated by stress and arousal. Empty onto hair follicle.
Eccrine-
More numerous,
Ubiquitious,
Used to regulate body temperature.
Empty onto skin.

44. Diseases, Disorders, and Injuries of the Integumentary System

45. Acne
What causes acne?

46. Acne
Acne
Body can produce an excess amount of sebum and dead skin cells
These build up in the hair follicles and form a plug
This creates an environment where bacteria (that we all have on our face) can thrive.
The openings of the sweat glands aren't normally involved in acne

47. Acne is a skin disturbance that typically occurs on areas of the skin that are rich in sebaceous glands (face and back).
Hormones, stimulate the release of sebum from sebaceous glands.

48. How is this child's skin different from yours?

49. Albinism
Albinism is a complete or partial absence of pigment in the skin, hair and eyes
Albinism results from inheriting a defective gene involved in the production of melanin.

50. How is this child's skin different from yours?

51. Defect in keritinization causes over shedding of cells
Netherton Syndrome
Defect in keritinization causes over shedding of cells

52. Skin Cancer
Caused by UV radiation causing direct or indirect damage to DNA of the cells.

53. Xeroderma Pigmentosum
Inherited genetic disorder in which the mechanisms which repair DNA after UV damage are deficient or absent.
Leads to EXTREAME susceptibility to skin cancer.

54. WARNING!
GRAPHIC CONTENT!