1. The Integumentary System Vocabulary Important Info Headings

2. General Anatomy A large organ composed of all 4 tissue types
22 square feet
1-2 mm thick
Weight 10 lbs.
2 Major layers of skin
Epidermis is epithelial tissue only
Dermis is layer of connective tissue, nerve & muscle
Subcutaneous Tissue (Hypodermis) (subQ or hypodermis) is layer of adipose & areolar tissue
subQ = subcutaneous injection
intradermal = within the skin layer

3. General Functions of the Skin
Regulation of body temperature
Protection as physical barrier
Sensory receptors
Excretion and absorption
Synthesis of vitamin

4. Thermoregulation Releasing of sweat onto the skin
perspiration & its evaporation lowers body temperature
Adjusting flow of blood to the body surface
in moderate exercise, more blood brought to surface helps lower temperature
with extreme exercise, blood is shunted to muscles and body temperature rises
Shivering and constriction of surface vessels
raise internal body temperature as needed
The above pictures are thermographs. They reveal the temperature variation around the body. The red and yellow areas are the hottest, while the green and blue areas are cold.

5. Protection Physical, chemical and biological barrier
tight cell junctions prevent bacterial invasion
Lipids released hinder evaporation
Melanin & other pigment protect somewhat against UV light
Langerhans cells alert immune system

6. Cutaneous Sensations of Skin
Touch
Temperature
Pressure
Vibration
Tickling
Some Pain sensations
Mechanoreceptor
Thermoreceptor
Pacinian Corpuscle
Merkel Cells
Nociceptor

7. Excretion Absorption Only a minor role is played by skin
400 mL evaporates daily
Small amounts salt, CO2, ammonia and urea excreted
Lipid soluble substances can be absorbed through the skin
vitamins A, D, E and K, Oxygen and CO2
acetone and dry-cleaning fluid, lead, mercury, arsenic, poisons in poison ivy and oak

8. Transdermal Drug Administration
Method by which drugs in a patch enter the body
Drug absorption most rapid where skin is thin (scrotum, face and scalp)
Examples
nitroglycerin (prevention of chest pain from coronary artery disease)
scopolamine (motion sickness)
estradiol (estrogen replacement therapy)
nicotine (stop smoking alternative)

9. Synthesis of Vitamin D Not a vitamin at all = Prohormone
Sunlight activates a precursor to vitamin D
Enzymes in the liver & kidneys transform that molecule into calcitriol (most active form of vitamin D)
Necessary vitamin for absorption of calcium from food in the gastrointestinal tract

10. Synthesis of Vitamin D Not a vitamin at all = Pro-hormone
About 80 % of vitamin D used in the body is produced when sunlight reacts with 7-dehydrocholesterol, a precursor sterol (cholesterol) in the skin, producing vitamin D3 or Cholecalciferol.
The liver then metabolizes vitamin D3 into 25-hydroxycholecalciferol or Calcidiol, the main form of vitamin D circulating in the blood.
The kidney, functioning as an endocrine gland, converts this precursor into two principal dihydroxylated metabolites or Calcitriol,—the primary active form of vitamin D
transported to various target organs:
bone, intestines, kidneys, where it binds to receptors and carries out further biochemical actions.
Calcidiol
Calcitriol

11. Epidermis Stratified squamous epithelium Contains no blood vessels
4 types of cells
5 distinct strata (layers) of cells

12. Cell types of the Epidermis
Keratinocytes--90%
produce keratin
Melanocytes %
produces melanin pigment
melanin transferred to other cells with long cell processes
Langerhan cells
from bone marrow
provide immunity
Merkel cells
in deepest layer
form light touch receptor with sensory neuron

13. Layers (Strata) of the Epidermis
Stratum corneum
Stratum lucidum
Stratum granulosum
Stratum spinosum
Stratum basale

14. Stratum Basale Deepest single layer of cells
Called stratum germinativum
Combo of merkel cells, melanocytes, keratinocytes & stem cells that divide repeatedly
Cells attached to each other & to basement membrane by desmosomes & hemidesmosomes

15. Stratum Spinosum 8 to 10 cell layers held together by desmosomes
During slide preparation, cells shrink and look spiny
Melanin (pigment protein) taken in by phagocytosis from nearby melanocytes

16. Stratum Granulosum 3 - 5 layers of flat dying cells
Show nuclear degeneration
Contain dark-staining keratohyalin granules
Contain lamellar granules that release lipid that repels water

17. Stratum Lucidum Seen in thick skin on palms & soles of feet
Three to five layers of clear, flat, dead cells
Contains precursor of keratin

18. A SECTION OF THE STRATUM CORNEUM WITH AN INTACT BARRIER FUNCTION
                                                                                                                    
                      
With the barrier 'intact' the opportunities for water loss is much less.
25 to 30 layers of flat dead cells filled with keratin and surrounded by lipids
Continuously shed
Barrier to light, heat, water, chemicals & bacteria
Friction stimulates callus formation

19. Keratinization & Epidermal Growth
Stem cells divide to produce keratinocytes
As keratinocytes are pushed up towards the surface, they fill with keratin
4 week journey unless outer layers removed in abrasion
Hormone EGF (epidermal growth factor) can speed up process
Psoriasis = chronic skin disorder
cells shed in 7 to 10 days as flaky silvery scales
abnormal keratin produced

20. Dermis
Connective tissue layer composed of collagen & elastic fibers, fibroblasts, macrophages & fat cells
Contains hair follicles, glands, nerves & blood vessels
Major regions of dermis
papillary region
reticular region

21. Papillary Region Top 20% of dermis
Composed of loose CT & elastic fibers
Finger like projections: Dermal Papillae
Gives rise to Friction Ridges = Fingerprints
Functions
anchors epidermis to dermis
contains capillaries that feed epidermis
contains Meissner’s Corpuscles (touch) & free nerve endings (pain & temp)

22. Reticular Region Dense irregular connective tissue
Contains interlacing collagen and elastic fibers
Packed with oil glands, sweat gland ducts, fat & hair follicles
Provides strength, extensibility & elasticity to skin
stretch marks are dermal tears from extreme stretching
Epidermal ridges form in fetus as epidermis conforms to dermal papillae
fingerprints are left by sweat glands open on ridges
increase grip of hand

23. Hypodermis (Subcutaneous Region)
Deepest layer
Missing on eyelids, nipples, genitals, and shins.
Insulator
conserving body heat
Shock absorber
protecting internal organs from injury
Stores fat as an energy reserve
incase extra calories are needed to power the body
The blood vessels, nerves, lymph vessels, and hair follicles also cross through this layer.

24. Skin Color Pigments Carotene in dermis
Melanin produced in epidermis by melanocytes
same # of melanocytes in everyone, but differing amounts of pigment produced
results vary from yellow to tan to black color
melanocytes convert tyrosine to melanin
UV in sunlight increases melanin production
Carotene in dermis
yellow-orange pigment (precursor of vitamin A)
found in stratum corneum & dermis
Hemoglobin
red, oxygen-carrying pigment in blood cells
if other pigments are not present, epidermis is translucent so pinkness will be evident

25. Clinical observations
freckles or liver spots = melanocytes in a patch
albinism = inherited lack of tyrosinase; no pigment
vitiligo = autoimmune loss of melanocytes in areas of the skin produces white patches

26. Skin Color as Diagnostic Clue
Jaundice
yellowish color to skin and whites of eyes
buildup of yellow bilirubin in blood from liver disease
Cyanotic
bluish color to nail beds and skin
hemoglobin depleted of oxygen looks purple-blue
Erythema
redness of skin due to enlarged capillaries in dermis
during inflammation, infection, allergy or burns
Stop

27. Accessory Structures of Skin
Functions
of Hair
Prevents heat loss
Decreases sunburn
Eyelashes help protect eyes
Touch receptors (hair root plexus) senses light touch
Epidermal derivatives
Cells sink inward during development to form:
hair
oil glands
sweat glands
nails

28. Structure of Hair Shaft Root Follicle visible
medulla, cortex & cuticle
HS round in straight hair
HS oval in wavy hair
Root
below the surface
Follicle
surrounds root
external root sheath
internal root sheath
base of follicle is bulb
blood vessels
germinal cell layer

29. Hair Related Structures
Arrector pili
smooth muscle in dermis contracts with cold or fear.
forms goosebumps as hair is pulled vertically
Hair root plexus
detect hair movement

30. Hair Growth Growth cycle growth stage & resting stage Growth stage
lasts for 2 to 6 years
matrix cells at base of hair root producing length
Resting stage
lasts for 3 months
matrix cells inactive & follicle atrophies
Old hair falls out as growth stage begins again
normal hair loss = hairs per day

31. Hair Color Result of melanin produced in melanocytes in hair bulb
Dark hair = true melanin
Blond and Red = melanin with iron and sulfur added
Graying = decline in melanin production
White hair = air bubbles in medullary shaft

32. Sebaceous (oil) glands
Secretory portion in the dermis
Most open onto hair shafts
Sebum
combination of cholesterol, proteins, fats & salts
keeps hair and skin soft & pliable
inhibits growth of bacteria & fungi (ringworm)
Acne
bacterial inflammation of glands
secretions stimulated by hormones at puberty

33. Sudoriferous (Sweat) Glands
Eccrine (sweat) glands
most areas of skin
secretory portion in dermis with duct to surface
regulate body temperature with perspiration
Apocrine (sweat) glands
armpit and pubic region
secretory portion in dermis with duct that opens onto hair follicle
secretions more viscous (milky)

34. Ceruminous glands
Modified sweat glands produce waxy secretion in ear canal
Cerumin contains secretions of oil and wax glands
Helps form barrier for entrance of foreign bodies
Impacted cerumen may reduce hearing

35. Structure of Nails Tightly packed, keratinized cells Nail body
visible portion pink due to underlying capillaries
free edge appears white
Nail root
buried under skin layers
Lunula is white due to thickened stratum basale
Eponychium (cuticle)
stratum corneum layer
Nail Matrix
deep to the nail root where growth occurs
Growth is 1mm per week--faster in summer & on most-used hand

36. Types of Skin Thin skin Thick skin covers most of body
epidermis (.1 to .15 mm.) lacks stratum lucidum
lacks epidermal ridges, has fewer sweat glands and sensory receptors
Thick skin
only on palms and soles
epidermis (.6 to 4.5 mm.) with distinct stratum lucidum & thick stratum corneum
lacks hair follicles and sebaceous glands

37. Epidermal Wound Healing
Abrasion or minor burn
Basal cells migrate across the wound
Contact inhibition with other cells stops migration
Epidermal growth factor stimulates cell division
Full thickness of epidermis results from further cell division

38. Deep Wound Healing
If an injury reaches dermis, healing occurs in 4 phases
Inflammatory Phase has clot unite wound edges and WBCs arrive from dilated and more permeable blood vessels
Migratory Phase begins the regrowth of epithelial cells and the formation of scar tissue by the fibroblasts
Proliferative Phase is a completion of tissue formation
Maturation Phase sees the scab fall off

39. Which phases have been left out of this illustration?
(TRY NOT TO LOOK AT YOUR NOTES!)

40. Scar Formation
Hypertrophic Scar remains w/in the boundaries of the original wound
Keloid Scar extends into previously normal tissue
collagen fibers are very dense and fewer blood vessels are present so the tissue is lighter in color
At the superior hole of this navel piercing there is a bead of hypertrophic scar tissue. This is a common complication of all piercings. It is usually a consequence of infection and/or trauma.
Typical example of hypertrophic scarring. Often called polyps. This is not a keloid, which is more pale in colour and softer too touch

41. Pressure Sores Decubitus ulcers
Caused by constant deficiency of blood flow to tissue
Areas affected is skin over bony prominence in bedridden patients
Preventable with proper care

42. Development of the Skin
Epidermis develops from ectodermal germ layer
Dermis develops from mesodermal germ layer
at 8 weeks, fetal “skin” is simple cuboidal epithelium
nails begin to form at 10 weeks
Nails do not reach the fingertip until the 9th month
dermis forms from mesoderm by 11 weeks
by 16 weeks, all layers of the epidermis are present
oil and sweat glands form in 4th and 5th month
by 6th months, delicate fetal hair (Lanugo) has formed
Slippery coating of oil and sloughed off skin called vernix caseosa is present at birth
Large amounts of vernix on babies feet, baby not yet rubbed down, baby approximately 60 seconds out of womb.

43. Burns Destruction of proteins of the skin chemicals, electrical, heat
Different types of burns 1 Epidermis skin layer 2 Dermis skin layer 3 Hypodermis skin layer 4 First degree burn 5 Second degree burn 6 Third degree burn

44. RULE OF 9’s Problems that result Way to determine the extent of burns
Body is divided into 11 areas for quick estimation
Each area represents about 9% of total body surface area
Problems that result
shock due to water, plasma and plasma protein loss
circulatory & kidney problems from loss of plasma
bacterial infection

45. Types of Burns First-degree Burn Second-degree Burn
only epidermis (sunburn)
Second-degree Burn
destroys entire epidermis & part of dermis
fluid-filled blisters separate epidermis & dermis
epidermal derivatives are not damaged
heals without grafting in 3 to 4 weeks & may scar
Third-degree or full-thickness
destroy epidermis, dermis & epidermal derivatives
damaged area is numb due to loss of sensory nerves
1ST
2ND
3RD

46. Skin Grafts
New skin can not regenerate if stratum basale and its stem cells are destroyed
Skin graft is covering of wound with piece of healthy skin
autograft from self
isograft from twin
autologous skin
transplantation of patients skin grown in culture
                                                             Continually evolving techniques for wound healing and tissue repair offer patients expanded opportunities for favorable outcomes.
STOP

47. Age Related Structural Changes
Collagen fibers decrease in number & stiffen
Elastic fibers become less elastic
Fibroblasts decrease in number
Langerhans cells and macrophages decrease in number and become less-efficient phagocytes
Oil glands shrink and the skin becomes dry
Walls of blood vessels in dermis thicken so decreased nutrient availability leads to thinner skin as subcutaneous fat is lost

48. Photodamage Ultraviolet light (UVA and UVB) both damage the skin
Acute overexposure causes sunburn
DNA damage in epidermal cells can lead to skin cancer
UVA produces oxygen free radicals that damage collagen & elastic fibers
lead to wrinkling of the skin

49. Skin Cancer 1 million cases diagnosed per year
3 common forms of skin cancer
Basal Cell Carcinoma (rarely metastasize)
Squamous Cell Carcinoma (may metastasize)
Malignant Melanomas (metastasize rapidly)
most common cancer in young women
arise from melanocytes ----life threatening!!!
key to treatment is early detection watch for changes in Asymmetry, Border, Color and Diameter
risks factors include-- skin color, sun exposure, family history, age and immunological status

50. I had this mole removed due to which danger…
I had this mole removed due to which danger…
A,B,C, and/or D? A B C D