1. Integumentary System 5

2. Functions of the Integumentary System
Chemical & physical barrier
Body temperature regulation
Cutaneous sensation
Synthesis of vitamin D

3. Skin (Integument)
Figure 5.1

4. Layers & Cells of the Epidermis:
stratum corneum
cell membranes filled with cross-linked keratin
stratum granulosum
dying cells filled with keratin & lipid granules
keratinocytes actively producing keratin filaments
stratum spinosum
stratum basale
mitotically dividing cells

5. Fibrous connective tissue, blood vessels, nerves & small muscles
Dermis
Fibrous connective tissue, blood vessels, nerves & small muscles
Papillary layer - areolar
Reticular layer - reticular

6. Subcutaneous layer not technically integument
Hypodermis
Subcutaneous layer not technically integument
Composed of adipose and areolar connective tissue
Thermal insulation & shock absorption

7. Pigments Hemoglobin Skin Color Melanin – reddish-brown
Carotene – yellowish-orange
Hemoglobin

8. Sweat Glands & Modified Sweat Glands
Eccrine – all over body, empty to pore
Apocrine –axillary & anogenital areas, empty to hair follicle
Ceruminous glands – secrete cerumen (ear wax)
Mammary glands – secrete milk

9. Simple alveolar glands distributed all over body
Sebaceous Glands
Simple alveolar glands distributed all over body
Oily secretion called sebum
Secreted to pore or hair follicle
Prevents desiccation & waterproofs skin

10. Keratinized Processes
Stratum corneum
Nail
Hair
Keratinization
soft & hard keratin
degree of crosslinking of keratin proteins
Keratin is a long filamentous protein
Transglutaminase joins glutamic acid residues on neighboring keratin proteins creating a keratin aggregate
~ 15 distinct keratin proteins

11. Epidermolysis bullosa
Keratin Diseases
Epidermolysis bullosa
Mutations in keratin proteins such that they can not be properly crosslinked

12. Structure of a Nail
Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes
Figure 5.4

13. Bundles of keratinized cells produced in follicles
Hair
Bundles of keratinized cells produced in follicles
Follicles are epithelial cells deeply invaginated into the dermal layer
Pigmented by melanocytes
Sensory nerve endings wraps each follicle
Connected to papilary dermis by tiny arrector muscle

14. Hair Follicle – Sagittal & Cross Sections

15. Vellus – lightly pigmented, finer body hair
Types of Hair
Vellus – lightly pigmented, finer body hair
Terminal – coarser, long hair
eyebrows, scalp, beard, axilla, and pubic
Coarseness determined by depth of follicle
Curliness determined by shape of follicle

16. Most common skin cancer
Basal Cell Carcinoma
Most common skin cancer
Stratum basale cells proliferate and invade the dermis and hypodermis
Slow growing and non-metastatic
Surgical excision effective in 99% of cases

17. Squamous Cell Carcinoma
Keratinocytes of stratum spinosum
Most frequent on scalp, ears, and lower lip
Rapid growing and metastatic
Early surgical removal followed by irradiation
Poor prognosis if metastasized

18. Most dangerous type of skin cancer
Melanoma
Cancer of melanocytes
Most dangerous type of skin cancer
Highly metastatic
Resistant to chemotherapy
Treated by wide surgical excision & immunotherapy
Chance of survival is poor if the lesion is over 4 mm thick

19. Melanomas are characterized by the ABCD rule
A: Asymmetric: halves of the pigmented unequal
B: Border: irregular with indentations
C: Color: black, brown, tan, sometimes red or blue
D: Diameter: larger than 6 mm

20. 1st -degree – only the epidermis
Burns
1st -degree – only the epidermis
localized redness, swelling, and pain
2nd -degree – epidermis and upper regions of dermis
Like first degree burns with blistering
3rd -degree – entire thickness of the skin is damaged
Burned area appears gray-white, cherry red, or black; no initial edema or pain

21. Estimates the severity of burns
Rule of Nines
Estimates the severity of burns
Burns considered critical if:
2nd degree > 25% of body
3rd degree >10% of body
3rd degree on face, hands, feet

22. Developmental Aspects of the Integument: Fetal
Epidermis develops from ectoderm
Dermis and hypodermis develop from mesoderm
Lanugo – downy coat of delicate hairs covering the fetus
Vernix caseosa – substance produced by sebaceous glands that protects the skin of the fetus in the amnion

23. Developmental Aspects of the Integument: Adolescent to Adult
Skin and hair become oilier and acne may appear
Skin shows the effects of cumulative environmental assaults around age 30
Scaling and dermatitis become more common

24. Developmental Aspects of the Integument: Old Age
Epidermal replacement of cells slows and skin becomes thinner
Skin becomes dry and itchy
Subcutaneous fat layer diminishes
Decreased elasticity and loss of subcutaneous tissue leads to wrinkles
Decreased numbers of melanocytes and Langerhans’ cells increase skin cancer risk