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)

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