1. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Ch 5 The Integumentary System Revised by Dr. Par Mohammadian 2012

2. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Overview  Functions  The Skin  Epidermis  Dermis  Skin Color  Skin Cancer  Burns  Developmental Aspects  Appendages of the skin  Glands  Sebaceous (oil)  Sweat (sudoriferous)  Ceruminous (wax)  Hair

3. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Integumentary System A. Regulation of Body Temperature B. Protection from Dehydration and Infection C. Respond to Temperature, Pressure, Pain D. Excretion of Water, Salts, Urea (nitrogenous waste) E. Synthesis Vitamin D (essential for Ca absorption) F. First Defensive Barrier of Immune Response Skin weighs 4-5 kg; 7% of total body weight Integument=covering

4. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Overview of Skin Structure A. Epidermis (epithelial tissue) (epi=upon) 1. stratum corneum (superficial) 2. stratum lucidum 3. stratum granulosum 4. stratum spinosom 5. stratum basale (deep) B. Dermis (connective tissue) 1. papillary layer 2. reticular layer

5. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.1 Skin structure. Epidermis Papillary layer Dermis Reticular layer Hypodermis (subcutaneous tissue; not part of skin)

6. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Different Cells of Epidermis 1.Keratinocyte - produce protein "keratin” (protective protein; kera=horn; cells arise from str. basale -> undergo mitosis -> being pushed upward -> by the time they reach the skin surface they are dead) 2.Merkel’s cells (tactile cells) - serve as touch receptors 3.Melanocyte - produce "melanin" (pigment; protects the cells from the damaging effects of UV radiation by the sunlight) 4.Dendrocytes (Langerhans cells) - assist in immunity (ingest foreign substances)

7. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Stratum spinosum Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin. Stratum basale Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and dendritic cells. Melanocyte Dendritic cell Keratinocytes Stratum corneum Most superficial layer; 20–30 layers of dead cells, essentially flat membranous sacs filled with keratin. Glycolipids in extracellular space. Dermis Melanin granule Sensory nerve ending Tactile (Merkel) cell Desmosomes Stratum granulosum Typically five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyaline granules. Layers of the Epidermis 1) 2) 3) 4) Avascular

8. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings 1) Stratum Basale (Stratum Germinativum) (germination) 1. origin of all cells of epidermis through mitosis 2. origin of cells for sweat-oil glands and hair 2) Stratum Spinosum (prickly: layer appear to have spine) 1. 8-10 rows of polyhedral shaped cells 2. contain spine-like projections ("spinosum") 3) Stratum Granulosum 1. cells from lower layers begin to die here 2. contain granules with keratohyalin (precursor to eleidin and keratin) Layers of the Epidermis

9. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

10. Structure of Dermis Dermis (derm=skin) (connective tissue) Overall Features 1. thick in some areas, thinner in others 2. contains blood supply, nerves, glands, hair follicle

11. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Epidermis Papillary layer Dermis Reticular layer Papillary Layer loose connective tissue dermal papillae cause ridges in the epidermis above (enhances gripping ability of the fingers and feet) Meissner's corpuscles - sense organ for touch small capillaries supply O 2 + nutrients Dermal papillae Reticular Layer dense, irregular connective tissue "collagen” contains: adipose, hair follicle, nerves, glands subcutaneous layer attaches skin to tissue below Paccinian corpuscles - sense pressure change

12. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Hypodermis  Subcutaneous layer deep to the skin (not part of the skin)  Composed of adipose and areolar connective tissue  Thickens when we gain weight (females: fat accumulation first in the thighs and breasts; males: anterior abdomen – beer belly)

13. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skin Color A. Melanin - pigment made in melanocytes 1. in basale and spinosum layers of epidermis 2. melanoblasts -> melanocytes in stratum basale 3. darkness due to melanin quantity (not cell #) 4. albinism - inability to produce melanin 5. vitligo - patchy loss of melanocytes 6. freckles - patchy concentration of melanocytes 7. UV light causes: tyrosine --> melanin production

14. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings B. Carotene 1. in stratum corneum and fatty areas of dermis 2. melanin + carotene = yellowish color C. Other Colors pink (Caucasian) – small amount of melanin => red appearance due to blood circulating in the capillaries

15. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skin Color in Diagnosis  Cyanosis  Blue skin color - low oxygenation of hemoglobin  Erythema (redness)  Fever, hypertension, inflammation, allergy  Pallor (blanching)  Anemia, low blood pressure, fear, anger  Jaundice (yellow cast)  Liver disorder  Bronzing  Inadequate steroid hormones in addison's disease  Bruises  Clotted blood beneath skin

16. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Skin Cancer The three major types of skin cancer are:  Basal cell carcinoma ( least malignant, str. basale proliferation)  Squamous cell carcinoma (second most common, str. spinosum)  Melanoma: Cancer of melanocytes is the most dangerous type of skin cancer because it is:  Highly metastatic  Resistant to chemotherapy

17. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Melanoma Melanomas have these characteristics (ABCD rule)  A: Asymmetry; the two sides of the pigmented area do not match  B: Border is irregular and exhibits indentations  C: Color (pigmented area) is black, brown, tan, and sometimes red or blue  D: Diameter is larger than 6 mm (size of a pencil eraser)

18. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Melanoma  Treated by wide surgical excision accompanied by immunotherapy  Chance of survival is poor if the lesion is over 4 mm thick

19. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Burns First-degree – only the epidermis is damaged  Symptoms include localized redness, swelling, and pain Second-degree – epidermis and upper regions of dermis are damaged  Symptoms mimic first degree burns, but blisters also appear Third-degree – entire thickness of the skin is damaged  Burned area appears gray-white, cherry red, or black; there is no initial edema or pain (since nerve endings are destroyed)

20. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Rule of Nines Estimates the severity of burns  Burns 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 face, hands, or feet

21. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.10 Partial thickness and full thickness burns. 1st-degree burn 2nd-degree burn Skin bearing partial thickness burn (1st- and 2nd-degree burns) Skin bearing full thickness burn (3rd-degree burn) 3rd-degree burn

22. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  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 Developmental Aspects of the Integument: Adolescent to Adult

23. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings  Epidermal replacement of cells slows and skin becomes thinner  Skin becomes dry and itchy  Subcutaneous fat layer diminishes, leading to intolerance of cold  Decreased elasticity and loss of subcutaneous tissue leads to wrinkles  Decreased numbers of melanocytes and Langerhans ’ cells increase the risk of skin cancer Developmental Aspects of the Integument: Old Age

24. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Overview  Functions  The Skin  Epidermis  Dermis  Skin Color  Skin Cancer  Burns  Developmental Aspects  Appendages of the skin  Glands  Sebaceous (oil)  Sweat (sudoriferous)  Ceruminous (wax)  Hair

25. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Glands A. Sebaceous Glands (sebaceous: greasy; oil glands)  Found all over the body (exception palm & soles)  Secrete: sebum - mixture fat, protein, cholesterol, salt  Generally connected to hair follicles  Prevent hair from becoming brittle, keep skin soft, anti-bacterial infected gland (sebum blocks the gland => white head – material oxidizes and dries => acne, blackheads Hormones (specially androgens) stimulate sebum secretion => during puberty activated)

26. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Dermal connective tissue Hair in hair follicle Sebaceous gland duct Sebaceous gland Photomicrograph of a sectioned sebaceous gland (90x) Secretory cells Sweat pore

27. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings B. Sudoriferous Glands (sudor: sweat; sweat glands) Perspiration (sweat) eliminates waste and heat  Apocrine Sweat Glands a. simple branched tubular glands b. only in axilla (arm pit), pubic c. in dermis, duct opens into a hair follicle  Eccrine Sweat Glands (eccrine: secreting) a. simple coiled tubular glands b. all over the body c. subcutaneous, opens onto epidermal surface (Composition: 99% water + NaCl; some vit C, antibodies, traces of metabolic wastes – urea, ammonia, uric acid) – heredity & diet!!!

28. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Figure 5.7b Photomicrograph of a sectioned eccrine gland (140x). Sebaceous gland Eccrine gland Sweat pore Duct Dermal connective tissue Secretory cells Photomicrograph of a sectioned eccrine gland (140x)

29. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings C. Ceruminous Glands  In the external auditory meatus (canal)  Cerumen - wax-like substance, prevents entry (cerumen = earwax)

30. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Hair (pili) – hard keratin A. Shaft - projects above surface of epidermis B. Root - below epidermis, penetrates into the dermis C. Hair Follicle - at the base a a single hair Functions include Warn of insects on skin Physical trauma Heat loss Sunlight Nutrition and hormones affect hair growth Average 2.25 mm growth per week

31. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Follicle wall Peripheral connective tissue (fibrous) sheath Glassy membrane Hair root Cuticle Cortex Medulla Hair matrix Hair papilla Melanocyte (Hair color) Subcutaneous adipose tissue Epithelial root sheath External root sheath Internal root sheath Hair shaft Arrector pili Hair root Hair bulb Sebaceous gland Diagram of a longitudinal view of the expanded hair bulb of the follicle, which encloses the matrix

32. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Follicle wall Peripheral connective tissue (fibrous) sheath Glassy membrane Epithelial root sheath External root sheath Internal root sheath Hair Cuticle Cortex Medulla Diagram of a cross section of a hair within its follicle Hair shaft Arrector pili Hair root Hair bulb Sebaceous gland

33. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings D. Arrector pili - smooth muscle, cause hair to rise, Responsible for "goose bumps” E. Hair root plexuses - nerve bundle responds to touch Arrector pili muscle Hair follicle Hair root Hair follicle receptor (root hair plexus)

34. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Types of Hair  Vellus – pale, fine body hair found in children and the adult female  Terminal – coarse, long hair of eyebrows, scalp, axillary, and pubic regions Hirsutism: (hirsut: hairy) Excessive hairiness – may result from an adrenal gland or ovarian tumor => large amounts of androgens

35. Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings Hair Thinning and Baldness  Alopecia – hair thinning in both sexes  True, or frank, baldness  Genetically determined and sex-influenced condition  Male pattern baldness – caused by follicular response to DHT