1. The Integumentary System5
The Integumentary System

2. Functions of the Integument
1. protects us from bacterial invasion
2. protects us from dessication
3. protects us from heat loss
4. protects us from UV radiation

3. Consists of three major regions
Skin (Integument)
Consists of three major regions
Epidermis – outermost superficial region
Dermis – middle region
Hypodermis (superficial fascia) – deepest region

4. Reticular layer of dermis
Hair shaft
Pore
Dermal papillae
(papillary layer
of dermis)
Epidermis
Meissner's corpuscle
Free nerve ending
Reticular layer of dermis
Sebaceous (oil) gland
Dermis
Arrector pili muscle
Sensory nerve fiber
Eccrine sweat gland
Pacinian corpuscle
Hypodermis
(superficial
fascia)
Artery
Vein
Hair root
Adipose tissue
Hair follicle
Eccrine sweat
gland
Hair follicle receptor
(root hair plexus)
Figure 5.1

5. Epidermis
4 major types of cells in the epidermis:
Keratinocytes – produce keratin which protects the skin
Melanocytes – protects the cell nuclei from UV radiation – gives us skin color
Langerhans cells – ingest foreign substances
Merkel cells – sensory receptor for touch
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6. Layers of the Epidermis
Figure 5.2b

7. Layers of the Epidermis
Stratum Basale – deepest layer next to dermis
a. continual mitosis
b. produces new keratinocytes and melanocytes

8. Layers of the Epidermis
Stratum Spinosum
Have filaments that function to resist tension and attach to the desmosomes
Have Langerhans cells and melanin granules and spiky kerantinocytes

9. Layers of the Epidermis
Stratum Granulosum
Keratinocytes change to flattened shape
Organelles disintegrate
Granules which form keratin
Granules which form a glycolipid waterproofing contained in extracellular space to slow water loss from epidermis
No capillarity above this layer

10. Layers of the Epidermis
Stratum Lucidum
Clear flat dead keratinocytes
Visible only in thick skin area of the body
Not present in thin skin areas of the body

11. Layers of the Epidermis
Stratum Corneum
Outermost layer
Protect against penetration and abrasion
Consists of dead cells (dead skin and dandruff)
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12. Dermis
Contains fibroblasts (produces fibers); macrophages (destroy bacteria and worn cells); mast cells (detect foreign substances and initiate the inflammatory response); white blood cells (take part of the immune response)
Supplied with nerve, blood, and lymphatic vessels
Contain hair follicle, oil and sweat glands

13. Second major skin region containing strong, flexible connective tissue
Dermis
Second major skin region containing strong, flexible connective tissue
Composed of two layers –
papillary
reticular

14. Layers of the Dermis: Papillary Layer
Touch receptors
Fingerprints
Gripping of hands and feet
Contain Meissner’s corpuscles (touch)
Contain Pacinian corpuscles (pain)

15. Layers of the Dermis: Reticular Layer
80% of the thickness of the skin
Collagen fibers in this layer add strength and resiliency to the skin
Elastin fibers provide stretch-recoil properties
Nourished by cutaneous plexus

16. Subcutaneous layer deep to the skin
Hypodermis
Subcutaneous layer deep to the skin
Composed of adipose and areolar connective tissue

17. Three pigments contribute to skin color
Melanin – yellow to reddish-brown to black pigment, responsible for dark skin colors
Freckles and pigmented moles – result from local accumulations of melanin
Carotene – yellow to orange pigment, most obvious in the palms and soles of the feet
Hemoglobin – reddish pigment responsible for the pinkish hue of the skin

18. Sweat Glands (sudoriferous glands)
prevent overheating of the body
secrete cerumen and milk
Eccrine – found in palms, soles of the feet, and forehead
Apocrine – found in axillary and anogenital areas
Ceruminous glands – modified apocrine glands in external ear canal that secrete cerumen
Mammary glands – specialized sweat glands that secrete milk

19. Soften skin when stimulated by hormones
Sebaceous Glands
Soften skin when stimulated by hormones
Secrete an oily secretion called sebum
Whitehead, blackhead, seborrhea

20. dead keratinized cells produced by hair follicles
Hair (Pili)
dead keratinized cells produced by hair follicles
Regions are shaft and root
Contains hard keratin
Consists of a core called the medulla, a cortex, and an outermost cuticle
Pigmented by melanocytes at the base of the hair

21. Shaft of Hair (Go to Microscope)
If shaft is flat and ribbon like (kinky)
If shaft is oval (silky and wavy)
If shaft is round (straight)
Locate medulla, cortex, cuticle
Look at the slides with beard hair (note the shape of the tip ends)
Pull a hair out by the root (observe the root tip)

22. Hair Function and Distribution
Functions of hair include:
Helping to maintain warmth
Alerting the body to presence of insects on the skin
Guarding the scalp against physical trauma, heat loss, and sunlight

23. Hair Follicle
Figure 5.5c

24. Vellus – pale, fine body hair found in children and the adult female
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

25. Structure of a Nail
Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes
Figure 5.6

26. Protection- Physical Barriers
Prevents bacterial invasion
Provides waterproofing with glycolipids
Does allow penetration of:
O, CO2, Vitamins A,D,E,K and steroids
Oleoresins (poison oak/ivy)
Organic solvents (paint thinner, acetone)
Salts and heavy metals (Pb,Hg)
Drug agents

27. Protection - Biological
Langerhans cells – detect foreign substances
Macrophages – viruses and bacteria
DNA-conversion of radiation to heat

28. Body Temperature Regulation
Constant secretion of sweat
Dilation of blood vessels and increased sweat production during excessive heat
Evaporation
Constriction of blood vessels and heat loss is slowed

29. Makes chemicals to aid liver function
Metabolic Functions
Synthesis of vitamin D in dermal blood vessels – aids in Ca absorption from digestive system
Makes chemicals to aid liver function
Makes enzymes that deter wrinkles

30. Blood reservoir – 5% of blood volume
Functions of Skin
Blood reservoir – 5% of blood volume
Excretion – sweat (amonia, urea, uric acid)

31. Skin Cancer
Most skin tumors are benign and do not metastasize
A crucial risk factor for nonmelanoma skin cancers is the disabling of the p53 gene
Newly developed skin lotions can fix damaged DNA

32. 3. Melanoma – cancer of melanocyts-most dangerous
Skin Cancer – 3 types
1. Basal cell carcinoma – least malignant and most common-stratum basale
2.Squamous cell carcinoma -stratum spinosum-most head,hands,can metastasize
3. Melanoma – cancer of melanocyts-most dangerous

33. Skin Cancers
Figure 5.7a–c

34. A: Asymmetry; the two sides of the pigmented area do not match
Melanoma – 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)

35. Burns considered critical if:
Rule of Nines - 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
Volume of fluid lost extimated by percentage of body surface burned
11 body areas – each 9%

36. Rule of Nines
Figure 5.8a

37. 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