1. The Integumentary System
Skin, Hair, Nails, and Glands

2. Do Now: Calculate the weight of your skin:
For average adult skin accounts for 7% of body weight!
Thickness ranges from 1.5mm – 4.0mm
Where on the body is it thickest? Thinnest?

3. Integumentary Structure
2 Components:
Cutaneous Membrane
Epidermis
Dermis
Hypodermis
aka subcutaneous layer
Superficial fascia
Accessory Structures
Hair
Nails
Exocrine Glands

4. Integumentary Function
Protection
Temperature maintenance
Synthesis and storage of nutrients
Sensory reception
Excretion and secretion

5. Epidermis Avascular & Keratinized Thick skin – 5 layers
Thin skin – 4 layers
New epidermis every days
Cells:
Keratinocytes (most cells) – produce keratin
Tightly connected by desmosomes
Callus – accelerated keratin formation
Melanocytes – (spider shaped) produce melanin
Melanin taken in by keratinocytes
Shields nucleus from UV
Merkel cells – sense skin curvature
Langerhans’ cells – star shaped phagocytes

6. Layers of Epidermis Layers (starting from basement membrane):
Stratum Germinativum (Basale)
3 Intermediate layers
Stratum Spinosum
Stratum Granulosum
Stratum Lucidum**
Stratum Corneum (superficial)

7. Stratum Germinativum (aka stratum basal)
Newly synthesized keratinocytes attached to basement by hemi-desmosomes
Forms ridge contours at interface of epidermal ridges and papillae of underlying dermis
Ridge contours are developmentally determined and visible in palmer, plantar, and digits
1 layer of Stem cells or germinative cells dominate the stratum germintivum
Undergoing mitosis
10-25% melanocytes, some merkel cells
Receives nourishment from dermis

8. Fingerprint Activity

9. Psoriasis Very common between 15-35 Autoimmune disease
increased rate of mitosis despite same rate of shedding
Non-contagious
Treated w/topically or phototherapy

10. Intermediate Strata Stratum Spinosum spiny or prickly layer
Newly synthesized keratinocytes (several layers)
Cells continue to divide
Langerhans cells abundant
Stratum Granulosum
3-5 flattened grainy cell layers
Stopped dividing, nuclei 7 organelles break down
Produce keratin (durable, water resistant protein)
Produce glycolipids –reduces water loss
Stratum Lucidum
Thin layer clear layer
Found in thick skin Densely packed cells filled with keratin

11. Stratum Corneum Most Superficial layer ¾ of epidermis
20-30 layers of flat dead keratinized or cornified cells
Held tightly together by desmosomes
Relatively dry (prevents microorganism growth)
Lasts about 2 weeks before shed
Avg person sheds 40lbs of skin in a lifetime!

12. Pigmentation: Skin Color
Melanin (yellow, brown or black pigment)
Produced by melanocytes in epidermis
Production increases in response to sun exposure
Prevents skin damage by absorbing UV rays
All humans have same number of melanocytes
Freckles & moles are areas of heavy melanin production
Carotene (orange-yellow pigment)
Converted to vitamin A for epithelial maintenance
Accumulates in stratum corneum
Dermal Circulation
Oxygenated Hemoglobin - reddish tint
Constricted blood vessels – pale
Cyanosis – Sustained constriction bluish color in Caucasian, only visible in nail beds of dark skin

13. What causes the appearance of wrinkled, leathery skin?

14. Sun Exposure UV stimulates production of vitamin D3
D3 is modified by liver and converted to calcitrol by kidneys
Calcitrol essential for absorption of calcium and phosphorus
Too much UV clumps elastin fibers causing leathery appearance
UV destroys folate needed for DNA synthesis
Too much UV can also cause chromosomal damage in stem cells of stratum germinativum causing skin cancer

15. Skin Cancer Most common form of cancer (and most preventable)
Basal Cell Carcinoma – originates in stratum germanitivum
Squamous Cell Carcinomas – superficial layers
Malignant Melanomas
Extremely dangerous
Begins as a mole
Melanocytes grow rapidly and metastasize through lymphatic system
Know the ABCD rule!

16. Do Now: What are Stretch Marks?
Damage to the dermis (collagen & elastin fibers) due to rapid stretching of the skin due to rapid growth or weight gain
Appear reddish- purple at first then fade to a lighter color over time
Tend to occur in regions of the body where fat is stored
Hormonal changes, genetics, and diet can all affect development of stretch marks

17. Dermis “hide” Striae – stretch marks Blisters
Dermis – contains network of blood vessels, lymph vessels, and nerve fibers
Papillary Layer (thin superficial)
Loose connective tissue
fibroblasts., macrphages, mast cells
Dermal Papillae indent epidermis
Supports and nourishes epidermis
Capillaries and nerves
Meissners corpsucles – touch receptors
Reticular Layer (80% of dermis)
Meshwork of dense irregular connective tissue
Elastic fibers provide stretch & recoil
Collagen fibers provide rigidity & strength
BV, sweat and oil glands
Phagocytes
Striae – stretch marks
Blisters

18. Cutis hyperelastica

19. Mechanoreceptors of Skin
Merkel’s disk
Skin Curvature
Meissner Corpuscle
Light Touch
Free Nerve Endings
Pain
Chemicals
Ruffini’s ending
Heat
Stretch
Pacinian Corpuscle
Deep Pressure
Vibrations

20. Sensory Homunculus

21. What causes a decubitus ulcer or bed sore?
Caused by an interruption of blood supply to a tissue causing necrosis. These develop in patients that have been bed ridden for long periods of time. They are caused by the weight of the body on the skin overlying a bony area compressing the blood supply.

22. Do Now: List & describe layers of the Integument
Epidermis
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum germanitivum (Basale)
Dermis
Papillary Layer
Reticular Layer
Hypodermis

23. Subcutaneous Layer Not actually part of integument, blurred boundary
Anchors skin to muscles, but loosely so it can slide
Loose connective tissue with many adipocytes
Fat distribution changes as grow and mature (shock absorption & insulation)
Females thighs & breasts
Males abdomen “beer belly”
Contains no vital organs and few capillaries
Subcutaneous injection useful method of administering drugs with hypodermic needle

24. Accessory Structures: Hair and Hair Follicles
2.5 million hairs on human body!!
Hair Growth Cycle
Hair grows for 2-5 years about .3mm per day then pushed to surface to be shed for new cycle to begin (scalp 6-10 yr cycle, eyebrows 3-4 months)
Function
Protect scalp from UV, cushion head, and insulate skull
Prevent entry of foreign particles in nostrils, ears, and eyes
Respond to stress or cold (arrector pili smooth muscle in dermis forces hair to stand up)
Structure
Walls of follicle contain cells of epidermis
Hair Papilla – peg of connective tissue containing capillaries and nerves, cell division occurs
Hair Root – anchors hair in to skin
Hair Shaft – 3 layers of dead keratinized cells
Medulla – core of hair (soft keratin)
Absent in fine hair
Cortex – surrounds medulla (hard keratin)
Cuticle – surface single layer made of overlapping shingles of cells

25. Hair Texture Oval – silky & wavy Flat & ribbonlike – curly
Round – straight
Conditioners – smooth out rough cuticles making it shiny
Split ends – cuticle wears away at ends

26. Hair Types: Cuticle Coronal Crown like (stacked paper cups)
Small rodents & bats
Spinous
Petal or triangular shaped
Mink, cats and seals
Imbricate
Flattened, overlapping scales
Humans and other animals
Medulla
Fragmentary (trace)
Discontinuous (broken)
Continuous
Cortex
Human pigment granules distributed by cuticle (except red-hair)
Cattle, dogs and some humans have ovoid bodies

27. Human Hairs vs. Animals
Consistent color & pigmentation throughout shaft (see banding in animals)
Animal pigmentation is centrally located
Humans 2 types of hair:
Vellus hair – fine body hair
Terminal hair – coarser, darker hair (increased testosterone increases growth)

28. Hair Color
Genetically determined by type and amount of pigment produced by melanocytes
Brown – true melanin
Blond - sulfur
Red - iron
Gray - Pigment production decreases
White air bubbles within hair shaft

29. Do Now: What is alopecia?
Hairs not replaced as fast as they are shed, begins anteriorly and progresses posteriorly
Male pattern baldness – sex linked trait by delayed action gene that when turned on changes response to testosterone
Until recently, only cure inhibits testosterone production

30. What are comedones?
Acne is caused by blocked sebaceous duct, forming a sebum plug
Affects over 85% of adolescents and young adults.
Secretions accumulate causing inflammation and possible bacteria infection
Blackheads – open comedones, melanin oxidizes turning black
Whiteheads – closed comedones
Hormonal changes can cause increased oil production
Try not to squeeze, scratch, pick, or rub the pimples. Although it might be tempting to do this, it can lead to skin infections and scarring.

31. Accessory Organs: Nails
Protect exposed finger tips and limit distortion when exposed to mechanical stress
Tools – pick up or scratch itch
Free Edge
Nail body – dead keratinized cells
Nail bed – epidermis covered by nail body
Nail root – anchors nail body
Nail matrix – nail growth occurs
Cuticle – portion of stratum corneum extending over nail
Lunula – pale crescent (area of obscured blood vessels)

32. Accessory Structures: Sebaceous Glands
Holocrine oil glands
Arrector pili muscle contracts squeezes the sebaceous gland forcing oily secretion out
Sebum (oily secretion) lubricates hair and skin and inhibits bacteria growth, slows water loss from skin
Glands are sensitive to androgens (sex hormones)
Cradle Cap – overactive sebaceous glands

33. Accessory Structures: Sudoriferous (sweat) Glands
About 3 million per person!
Merocrine (eccrine) Sweat Glands
Secreted directly onto surface of skin via exocytosis
99% water w/electrolytes, vitamin C, antibodies, metabolic wastes and drugs, pH of 4-6
Cools surface of skin and lowers body temp
Too much perspiration may lead to dehydration
Flushes microorganisms from surface
Apocrine Sweat Glands
sweat glands that secrete products into hair follicles in armpits, nipples, and groin
Sticky, cloudy secretion released at puberty
Odorous as bacteria break it down as food

34. Slides of Scalp vs. Palm

35. Injury and Repair of Skin
Inflammatory response – triggered by mast cells increase blood flow to area
Scab (fibrin proteins) forms at surface to restrict entry of microorganisms
Cells divide rapidly to replace missing cells
Macrophages and phagocytes clear debris and patrol area for pathogens
Animation:
Deeper wounds
Scar tissue – lots of collagen fibers and few blood vessels
Fetuses don’t scar
Keloid – thickened area of scar tissue with shiny smooth surface (tend to form in adults with dark skin)
Damaged hair follicles, sebaceous and sweat glands, muscle cells and nerves are rarely repaired
Burns
1st degree – kills superficial epidermal cells, injures papillary dermis
2nd degree – kills epidermis and possible some dermis, injures reticular dermis
3rd degree – kills all epidermal and dermal cells, injures hypodermis and deeper tissues
Skin Gun:

37. Aging
Epidermis thins as stem cell activity decreases increasing skin injuries and infections
Number of macrophages and other immune system cells decreases
Decline in vitamin D3 production reduces calcium and phosphorus absorption weakening muscles and bones
Melanocyte activity decreases causing increases sensitivity to sun
Gland activity decreases causing dry scaly skin
Follicles decrease function creating thin light hair
Elastic fibers decrease resulting in wrinkling
Reduced blood supply to dermis – less thermoregulation
Repairs are slow…6-8 weeks

38. Write an analogy for our skin….
Human skin is like __________ because _______________.

39. Cardiovascular System
Do Now:
Integumentary System
Skeletal System
Muscular System
Nervous System
Endocrine System
Cardiovascular System
Lymphatic System
Respiratory System
Digestive System
Urinary System
Reproductive System
Complete web showing how Integumentary system interconnected w/other organ systems!