1. The Integumentary System

2. The Integumentary System
Integument is skin
Skin and its appendages make up the integumentary system
Two distinct regions
Epidermis
Dermis
A fatty layer (hypodermis) lies deep to it

3. Functions of skin Protection Synthesizes vitamin D with UV
Cushions and insulates and is waterproof
Protects from chemicals, heat, cold, bacteria
Screens UV
Synthesizes vitamin D with UV
Bones need vitamin D to make new bone cells. Vit. D is the only vitamin your body can make on it’s own. Sunskin cellsliver and kidneys activate Calcitrolmakes bones.
Regulates body heat (thermoregulate)
Prevents unnecessary water loss
Sensory reception (nerve endings)
Bones need vitamin D to make new bone cells. D is the only vitamin your body can make on it’s own. Sunskin cellsliver and kidneys activate Calcitrolmakes bones.

4. Epidermis Keratinized stratified squamous epithelium
Four types of cells
Keratinocytes – deepest, produce keratin (tough fibrous protein)
Melanocytes - make dark skin pigment melanin
Merkel cells – associated with sensory nerve endings. Light and deep touch
Langerhans cells – macrophage-like dendritic cells. From bone marrowimmunity
Everyone has same number of melanocytes, but the breadth of cellular extensions affects the control of melanin
Melanosomes-organelles that give us pigment and color of skin. Dark skin has more melanosomes
North—need low amounts of melanin to synthesize Vitamin D…so sun can get through the skin.
Equator-where sun is intense, need more melanin to block sun’s rays and the destruction of folic acid and protect from skin cancer.

5. Epidermis 4 layers of cells in most areas of body
5 layers where extra protection is needed (palms and soles)

6. Mneumonics Come---Stratus Corneum Let’s ---Stratus Lucidum
Get---Stratus Granulosum
Sun ---Stratus Spinosum
Burned---Stratus Basale

7. (see figure on next slide)
Epidermal Layers
Layers (from deep to superficial)
Stratum basale or germinativum – single row of cells attached to dermis; youngest cells (mitosis) migrate up from here to the corneum.
Stratum spinosum – spinyness is artifactual; tonofilaments (bundles of protein) resist tension
Stratum granulosum – layers of flattened keratinocytes producing keratin (hair and nails made of it also). No capillaries. Cells essentially dying so nutrients only get there through diffusion
Stratum lucidum (only on palms and soles)
Stratum corneum – horny layer (cells dead, many layers thick). They leave us and replaced by cells below.
(see figure on next slide)

8. Epithelium: layers (on left) and cell types (on right)

9. Remember… Four basic types of tissue
Epithelium – epidermis just discussed
Connective tissue - dermis
Muscle tissue
Nervous tissue

10. Dermis Strong, flexible connective tissue: your “hide”
Cells: fibroblasts, macrophages, mast cells, WBCs
Fiber types: collagen, elastic, reticular
Rich supply of nerves and vessels (vascular)
Critical role in temperature regulation (the vessels)
Two layers (see next slides)
Papillary – areolar connective tissue; includes dermal papillae friction ridges (fingerprints)
Reticular – “reticulum” (network) of collagen and reticular fibers..dense irregular CT, nerve fibers

11. *Dermal papillae
*Dermis layers * *

12. Epidermis and dermis of (a) thick skin and (b) thin skin
(which one makes the difference?)

13. Fingerprints, palmprints, footprints
Dermal papillae lie atop dermal ridges
Elevate the overlying epidermis into epidermal ridges
Are “sweat films” because of sweat pores
Genetically determined
Flexion creases
Deep dermis, from continual folding
Fibers
Collagen: strength and resilience
Elastic fibers: stretch-recoil
Striae: stretch marks
Tension lines (or lines of cleavage)
The direction the bundles
of fibers are directed
The dermis is the receptive site for the pigment of tattoos

14. Langer’s Cleavage lines
Dense bundles of white collagen fibers that make up reticular layer of dermis orient themselves in patterns.
Incisions made across Langer’s cleavage lines heal more slowly than cuts made along or parallel to Langer’s cleavage lines.

15. Nervous System Cells Tctile-touch (dermal Papillae)
Tactile Receptors
Tactile corpuscles (Meissner’s corpuscles) provide fine touch, pressure and vibration information
These are located mainly in the eyelids, lips, fingertips, nipples and genitals
Nerve endings are covered by modified Schwann Cells
Tctile-touch (dermal Papillae)
Lamellar-pressure (dermis)
Lamellated corpuscles are receptors that are sensitive to dep pressure and high frequency vibration
These are located in skin, fascial and the joint capsules
They cover their dendrites to e able to shield themselves from other types of simulation other than deep pressure

16. Hypodermis “Hypodermis” (Gk) = below the skin
“Subcutaneous” (Latin) = below the skin
Also called “superficial fascia”
“fascia” (Latin) =band; in anatomy: sheet of connective tissue
Lots of CT (reticular fibers (strong), adipocytes, mesenchymal cells (stem cells), elastic fibers, collagen fibers, fibroblast, macrophages)
Fatty tissue which stores fat and anchors skin (areolar tissue and adipose cells)
Different patterns of accumulation (male/female)

17. Skin color Three skin pigments
Melanin: the most important
Carotene: from carrots and yellow vegies
Hemoglobin: the pink of light skin
Melanin in granules passes from melanocytes (same number in all races) to keratinocytes in stratum basale
Digested by lysosomes
Variations in color
Protection from UV light vs vitamin D?
Everyone has same amount of melanin, but cellular extensions will change the amount/ appearance of melanin
Can see nucleus, golgi, ER of melanocyte…melanin are the pigment granules (dots ) in the extensions. Cells are in epidermis, pink line is basement membrane and dermis underneath that.

18. Melanocytes

19. Skin appendages Derived from epidermis but extend into dermis Include
Hair and hair follicles
Sebaceous (oil) glands
Sweat (sudoiferous) glands
Nails

21. Functions of hair Warmth – less in man than other mammals
Sense light touch of the skin
Protection – scalp
waterproofing

22. Hair and hair follicles: complex Derived from epidermis and dermis Everywhere but palms, soles, nipples, parts of genitalia
*“arrector pili” is smooth muscle *
Hair bulb: epithelial cells surrounding papilla
Hair papilla
is connective tissue________________

23. Make up of hair – hard keratin
Parts
Root imbedded in skin
Shaft projecting above skin surface
Make up of hair – hard keratin
Papilla have capillaries and nutrients coming in. Matrix one layer think making new cells—push up dead cells with tons of keratin->pushed up past sebaceous glands
Three concentric layers
Medulla (core)
Cortex (surrounds medulla)
Cuticle (single layers, overlapping)

25. Shaft & Root Shaft—where keratinization complete
Root where keratinization is happening.
Basically a tube of epidermal cells where young and dividing cells are constantly being pushed up.

26. Hair growth: averages 2 mm/week
Types of hair
Vellus: fine, short hairs
Intermediate hairs
Terminal: longer, courser hair
Hair growth: averages 2 mm/week
Active: growing
Resting phase then shed
Hair loss
Thinning – age related
Male pattern baldness
Hair color
Amount of melanin for black or brown; distinct form of melanin for red
White: decreased melanin and air bubbles in the medulla
Genetically determined though influenced by hormones and environment

27. Nails Of hard keratin Corresponds to hooves and claws
Grows from nail matrix (lunule)
Lots of vascular tissue below nail (dermis)
Eponychium makes the cuticle
Made same way as hair
Matrix down at the bottom
Epidermis on sides and top that dives down into the dermis; quickly makes nail with dead cells filled with keratine
Eponychium makes the cuticle
Crescent moon called lunula is the active nail matrix where growth originates

28. Sebaceous (oil) glands
Entire body except palms and soles
Produce sebum by holocrine secretion
Oils and lubricates
waterproofs

29. Sweat glands
Entire skin surface except nipples and part of external genitalia
Prevent overheating
500 cc to 12 l/day! (is mostly water)
Humans most efficient (only mammals have)
Produced in response to stress as well as heat

30. Types of sweat glands Eccrine or merocrine Apocrine
Most numerous
True sweat: 99% water,
some salts, traces of waste
Open through pores
Most abundant palms, soles, forehead
Apocrine
Axillary, anal and genital areas only
Ducts open into hair follicles
The organic molecules in it decompose with time - odor
Modified apocrine glands
Ceruminous – secrete earwax
Mammary – secrete milk
3 million eccrine glands in body
2000 apocrine glands
Deodorant –doesn’t stop sweat, but masks odor by attacking stink making bacteria
Antiperspirant-uses aluminum to block sweat glands. Aluminum gets absorbed by cells lining eccrine glands then water follows by osmosis and stratified cuboidal cells wills well, clos off ducts and prevent sweating.

31. Pore
Duct of eccrine gland
Sebaceous gland
Eccrine gland

32. Sweat duct pores-Palm of hand

33. Disorders of the integumentary system
Burns
Threat to life
Catastrophic loss of body fluids
Dehydration and fatal circulatory shock
Infection
Types
First degree – epidermis: redness (e.g. sunburn)
Second degree – epidermis and upper dermis: blister
Third degree - full thickness
Infections
Skin cancer

34. Burns First-degree Second-degree Third-degree
(epidermis only; redness)
Second-degree
(epidermis and dermis,
with blistering)
Third-degree
(full thickness, destroying epidermis, dermis, often part of hypodermis)

35. Critical burns Over 10% of the body has third-degree burns
Estimate by “rule of 9’s”
Over 10% of the body has third-degree burns
25 % of the body has second-degree burns
Third-degree burns on face, hands, or feet

36. Tumors of the skin Benign, e.g. warts
Cancer – associated with UV exposure (also skin aging)
Aktinic keratosis - premalignant
Basal cell - cells of stratum basale
Squamous cell - keratinocytes
Melanoma – melanocytes: most dangerous; recognition:
A - Asymmetry
B - Border irregularity
C - Colors
D - Diameter larger than 6 mm

37. Skin Cancer
Sqaumous cell carcinoma
Basal cell carcinoma
Melanoma

38. Skin Cancer
Squamous cell Basal cell Malignant Carcinoma Carcinoma Melanoma

39. Epidermal Wound Healing

40. Injury into Dermis Site of injury Fills with blood Scabs Fibroblasts
Scar tissue

41. Other Clinical Symptoms
Blue skin-cyanosis
Heart failure
Too cold for too long
Poor circulation
Respiratory issues
As oxygen levels decrease blood turns a darker color and through the clear skin will look blue as blood leaves the surface
Skin has a lot of blood vessels near the surface so blood vessels will constrict causing blood to move deeper into your tissues and help keep vital tissue/organs warm. Once warm the blood vessels will gradually relax and allow blood to return to the surface.

42. Jaundice
Liver disorder as yellow bile accumulates in blood stream yellow skin
Erythema
Red skin
Fever, inflammation, allergy
Blood vessels expand and more blood goes to skin surface