Integumentary System: Skin & Body Membranes
Body Membranes
• Divided into two categories:– epithelial membranes
• cutaneous (skin/integumentary)
• mucous• serous
– connective tissue membranes
• synovial
Mucous membranes• Composed of
– epithelium (varies based on site)• typically stratified squamous or
simple columnar– (below) loose connective tissue
(lamina propria)• Lines all body cavities open to exterior• Adapted for absorption and secretion• Typically “wet” tissue
Serous membranes(serosa)
• Composed of:– Simple squamous – Line cavities NOT open to exterior
– exceptions are dorsal body cavity and joint cavities
• Occur in pairs:– Parietal layer– Visceral layer
• Serous fluid separates these membranes
Connective Tissue Membranes(Synovial membranes)
• NO epithelial tissue at all• Line the capsules that surround
joints• Provide smooth surface• Secrete lubricating fluid• Line sacs of connective tissue called
bursae and tendon sheaths– Provide cushioning for organs
moving against one another during muscular activity
Visual Summary
Visual Summary
Integumentary System(a.k.a., cutaneous membrane and/or skin)
• Basic Functions:– insulates and cushions deeper body organs– protects body from:
• mechanical, chemical, thermal & ultraviolet damage
• bacteria– regulates heat loss– excretion (urea, salts, water)– manufacturing of immunity proteins– vitamin D synthesis– sensory reception
• Structure:– Epidermis
• full or keratin (protein)• capable of keratinizing (hardening)• hardened skin is “cornified”
– Dermis• dense connective tissue
– Subcutaneous tissue or Hypodermis• Deep to dermis• Basically adipose (fat) tissue (not
technically skin)• Shock absorption and attaching
organs to skin
Hypodermis
Hypodermis
Epidermis• Composed of five “strata” (deep to surface):
– stratum basale– spinosum– granulosum– lucidum– corneum
• Avascular (no blood supply)• Most cells are keratinocytes
– make strong proteins
Epidermis• Stratum basale
– closest to dermis– contains only cells that receive nourishment from dermis– constantly dividing (stratum germinativum)
• daughter cells pushed to surface
• Stratum spinosum and granulosum– more flat and full of keratin; die
• Stratum lucidum– clear layer on extra thick and hairless skin
• palms and soles of feet
Epidermis• Stratum corneum
– Outermost layer
– 20-30 layers thick
– Cells are dead and completely keratinized
• called cornified or horny cells
• New epidermis layer forms every 25-45 days
Epidermis
Pigments and Their Imbalances• Melanocytes (found in stratum basale)
– create pigment melanin– tanning causes melanocytes to
create more melanin– Freckles and moles are
concentrated melanin• Imbalances
– excessive sun causes elastic fibers to clump (leathery skin)
• depresses immune system (herpes simplex)
• causes skin cancer
Skin Cancer: The “ABCDE’s”
1. Asymmetrical skin lesion 2. Border of lesion is not
normal 3. Color of melanoma usually
has multiple colors 4. Diameter of the moles- five
millimeters of more 5. Evaluation, of a changing
mole
Conjunctival Melanoma Iris MelanomaIris Melanoma
Breast Cancer from Melanoma: Male Patient
Dermis (a.k.a., hide)
• Two regions:– Papillary
• upper dermal region
• uneven with fingerlike projections called dermal papillae (feed into epidermis above)
– contain “capillary loops” for nutrients
– others contain pain receptors
– touch receptors called Meissner’s corpuscles
• on hands and palms
– Help with gripping
– Form fingerprints
Dermis (a.k.a., hide)
• 2nd Layer:– Reticular
• Deepest skin layer• Contains:
– blood vessels, sweat & oil glands, and deep pressure receptors (Pacinian corpuscles)
• Filled with phagocytes to attack any bacteria that have gotten this deep
Dermis (a.k.a., hide)
• Collagen and elastic fibers plentiful in dermis– Collagen:
• toughness of layer
• attract water to keep skin hydrated
– Elastic:• gives skin elasticity in youth
• Collagen & elastic fibers & fat stores diminish with age
Ehlers-Danlos Syndrome
Dermal Imbalances• When blood flow is restricted via pressure
(i.e., bedridden hospital patients)– skin cells die– cracks form– permanent damage of blood vessels and
tissue form decubitus ulcers
Skin Color• Three pigments affect skin color:
– Melanin• amount and kind
– yellow, red-brown or black– Carotene
• amount deposited in subcutaneous layer• eating large amounts will make someone look yellow-
orange– Oxygen bond to hemoglobin
• a lot of oxygen gives a reddish appearance
Pigment Imbalances• Cyanosis
• Other influences on skin color– Redness or erythema– Pallor or blanching– Jaundice– Bruises or black-and-blue marks
Appendages of the Skin
• Cutaneous glands– all exocrine glands– Two types:
• Sebaceous glands• Sweat glands Hairs
• Hair follicles
• Nails
http://www.abc.net.au/science/news/stories/
s888984.htm
http://www.doctorsecrets.com/your-skin/cause-of-acne.html
Cutaneous glands• Sebaceous glands (Oil glands)
– Everywhere on body except palms and soles– Secrete into hair follicle or skin surface– Produce sebum
• lubricating• germ fighting• levels increase as male hormones increase
• Imbalances– Acne– Seborrhea
Cutaneous glands• Sweat glands (Suderiferous)
– approx. 2.5 million glands per person– two types:
• Eccrine– more numerous– produce sweat (water, salt, vit. C, ammonia,
urea, lactic acid)
• Apocrine– confined to armpit and genital areas– role not quite understood (pheromones?)– activated by pain, stress, sexual stimulation
Hairs• Minimal usefulness:
– head bumps– eye protection– respiratory protection– Minimal insulation
• Structure:– Flexible epithelial structure– Root
• within follicle
– Shaft• exposed projection
Hairs• Produced by hair follicle
– grows via division of stratum basale epithelial cells in “growth zone” (a.k.a., hair bulb matrix)
– daughter cells pushed away from bulb keratinize and die
Random Hairy Guy
Guinness World Record Holder
Guinness World Record Holder
Nails• Analogous to hoof/claw of animals
Guinness World Record Holders
Not a Guinness World Record Holder
Congenital Generalized Hypertrichosis
Senior Tattoos!
Extreme Weight Loss
Imbalances
Imbalances
Boil-carbuncles
Imbalances
Imbalances
Imbalances
Herpes Gladiatorum
Miscellaneous Skin Disorders
Miscellaneous Skin Disorders
Methicillin-resistant Staphylococcus aureus (MRSA)
H.I.V.’s effects on the Integumentary System
Burns• Moderate to severe damage of skin• Severe cases result in death due to:
– loss of fluid– circulatory shock
• Burned skin is sterile for approx. 24 hours– then becomes septic– fungus and bacteria invade– immune system suppressed
Burn Severity• 1st Degree
– just epidermis is damaged– ex., sunburn
• 2nd Degree– epidermis and upper dermis damaged– blisters result– ex., extreme sunburn
• 3rd Degree– full skin layer is destroyed– appear gray-white, blackened– nerves destroyed so not painful
Burn Severity
Integumentary Structures
Skin Receptors
Krause Corpuscle
• Type: Pressure
• Location: Lips, Tongue & Genitals
Pacinian Corpuscle
• Type: Vibration of 150-300 htz
• Location: Dermis of Hairy Skin
Ruffini Endings
• Type: Pressure Receptors
• Location: Dermis of Hairy Skin
Meissner Corpuscle
• Type: Vibration 20-40 htz
• Location: Glabrous skin (hairless)
Free Nerve Endings
• Type: Varied (Mechanical, Thermal, Noxious)
• Location: Varied
Sensory Organs in Skin• Free Nerve Endings
– Wide variety of types • Can detect mechanical pressure, thermal
pressure, noxious, chemical, etc.– Found all over the integument
• Thermoreceptors
– Warm receptors:• Temperatures above 77° F (25° C) up to 113° F (45° C).
Which also triggers pain receptors
– Cold receptors:• Temperatures between 50° F (10° C) to 68° F (20° C).
Under 50° F the pain receptors are triggered. Both receptors function at temperatures in between and rapidly adapt.
Merkel Cells
• Type: Pressure
• Location: Epidermis
Merkel Cell Carcinoma