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Membranes &
The Integumentary
System
Did you know….
• The skin is the largest organ of the human body. It has a surface area of about 25 square-feet!
• You shed about 1.5 pounds of skin particles each year. (That’s 105 lbs by the age of 70!)
• There are 32 million bacteria on every square inch of your skin!
The Integumentary System:ANATOMY
• Includes:
- Skin (integument)
- Hair
- Nails
- Exocrine glands (oil & sweat)
- Nerve receptors
“Appendages”
PHYSIOLOGY (functions)• Protection
• Regulation of body temperature
• Responds to environment
• Excretion
• Makes Vitamin D
MEMBRANES
• Two Types:
– Epithelial
– Connective Tissue
EPITHELIAL
• Cutaneous– Largest
– Skin
– Main function: protection, response
• Serous—2 types:– Parietal: Lines the walls of body cavity; lungs
(pleura)
– Visceral: Lines cavities of internal organs (peritoneum)
– Secrete a watery solution for lubrication
EPITHELIAL (cont.)
• Mucous
– Lines body surfaces open to exterior
– Respiratory, digestive, urinary,
reproductive tracts
– Cells secrete mucus (thick, slimy material
that lubricates the membranes)
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CONNECTIVE TISSUE MEMBRANES
• Synovial
– Line spaces between bones (joints)
– Cells secrete synovial fluid (lubricates the joints)
– Helps reduce friction between bones
– Also found in bursae (sacs found in joints)
THE SKIN
• 2 Layers:
– Epidermis:
Outermost, thinner layer; epithelial tissue
– Dermis: Deeper and thicker; connective tissue
EPIDERMIS
• Composed of 5 layers (from deep to
superficial)
– Stratum basale/germinativum
• mitosis occurs here to replace lost cells from s. corneum
• Melanin (skin pigment) is found here; produced by melanocytes
• Cyanosis: bluish color of skin due to lack of melanin & low skin blood/oxygen level
– Stratum spinosum: touch receptors
– Stratum granulosum: produces keratin
EPIDERMIS
– Stratum lucidum—cells die & become
clear; not in all areas of the skin (hairless, thick areas)
– Stratum corneum
• Outermost; contains dead cells;
contains keratin (hard protein)
• Desquamate--
DERMIS(nerves, blood vessels, hair follicles, & glands)
• Composed of 2 layers:
1. Papillary layer
• Upward projections (waves) that
connect dermis to epidermis called
dermal papillae
• Pain receptors
• Touch receptors (Meissner’s corpuscles)
• Give rise to fingerprints
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DERMIS2. Reticular Layer
• Made of mostly connective tissue
• Contains collagen fibers (strength) & elastic fibers (stretching)
• Many nerve endings for pain, touch, pressure (Pacinian corpuscles)
• Many phagocytes (eat bacteria)
• Contains oil & sweat glands and blood vessels
Aging of Skin
• Number of fibers decreases
• Subcutaneous layer decreases in fat—
leads to wrinkles
• Striae---stretch marks
• Lines of cleavage—indicates direction of collagen fibers; surgeons use these
Subcutaneous Layer/
Hypodermis
• Layer beneath dermis
• FAT!!!!
Skin Color• Comes from
– Melanin (epidermis)
– Carotene (dermis)
– Blood vessels (dermis)
• MELANIN—protective pigment against UV radiation
– Black/brown color
– Freckles—patches of melanin
Disorders that affect skin color:
• Albinism –
melanocytes do not produce melanin
• Vitiligo – patches of
skin do not contain
melanocytes
• CAROTENE—
– Found in stratum corneum of epidermis and fatty areas of dermis
– Combination of carotene and melanin give skin a yellow/orange color
• BLOOD VESSELS—give a pink color
– Vasodilation: enlarged blood vessels
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Skin color
• Emotions and illness can influence skin color
APPENDAGES OF THE SKIN(epidermal derivatives but extend into the dermis)
• Hair
• Nails
• Receptors
• Glands
HAIR• Structure:
– Shaft—visible part of hair; has a lot of pigment & keratin
– Root—penetrates the dermis in follicle
• Papilla of hair—hair begins to grow here; blood vessel supplies nourishment
• Arrector pili: smooth muscle attached to hair follicle; causes goosebumps
when contracted
Hair Facts
• Hair Color: depends on type of melanocytes in hair bulb and
how much melanin
• Hair Loss (Alopecia):
– Men � hormone levels decrease
with age
– Other causes � autoimmune disease; drug therapy; infection; psychological (stress)
GLANDS
• 2 kinds:
–Sebaceous (oil)
–Sudoriferous (sweat)
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SEBACEOUS GLANDS
• Secrete oil called sebum (moistens hair
& skin)
• Attached to hair follicles
• Large in face and neck
• More is produced during teen years because of hormones
• Whiteheads—accumulation of sebum
• Blackheads—sebum, dirt, & bacteria
SUDORIFEROUS (SWEAT) GLANDS
• Most numerous
• Produces sweat (perspiration) &
composed of water, salt, sugars, &
sometimes bacteria
• Eliminates wastes & regulates body
temperature
SUDORIFEROUS (SWEAT)
GLANDS• 2 Groups:
1. Apocrine
• found in the axillary region
• Large
• formed at onset of puberty
• produce a thicker (viscous), more odorous secretion than sweat. The odor
comes from bacteria.
• Smelly sweat
SUDORIFEROUS (SWEAT) GLANDS
2. Eccrine—
• Small
• Numerous; most common
• over the whole body (mainly palms & soles of feet)
• produce perspiration—watery; salty sweat
CERUMINOUS (WAX) GLANDS
• Produce cerumen (wax & oil)
• Found in the ear
• Function: prevent entrance of foreign particles
NAILS
• Parts of a nail:
– Nail body—visible part of nail;
– Free edge—part that hangs over nail bed
– Root—hidden by cuticle (fold of skin)
– Lunula—”little moon”; white area at base of nail body
– Nail bed—under nail body; contains blood vessels (the “quick”); gives pinkish color
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RECEPTORS
• Send messages to brain concerning
touch, pain, temperature, pressure.
• Meissner’s corpuscle—light touch
(epidermis)
• Pacinian corpuscle—pressure (dermis)
• Free nerve endings—pain
BURNS
• Classified by:
1) Depth of burn
2) The amount of body surface area affected
Use RULE OF NINES to determine severity of burns.
CLASSIFICATION OF BURNS(Depth of burns)
• 1st Degree– Minor
– Involves upper layers of epidermis only
– Minimal damage
• 2nd Degree– Involves ALL of epidermis & upper dermis
– Blisters, pain, swelling
– Scarring
– Called “partial-thickness burns”
•3rd Degree
•Called a “full thickness burn”•Completely destroys all of epidermis
& dermis & into subcutaneous layer
•Insensitive to pain•Much fluid loss—big problem
•Great risk of infection
BurnsBurns
(cont’d)
First-degree(epidermis only; redness)
Second-degree(epidermis and dermis,with blistering)
Third-degree(full thickness, destroying epidermis, dermis, often part of hypodermis)
RULE OF NINES
• Body is divided into 11 areas (9% each)
with the extra 1% being the genital region.
• Diagram on p. 125:
– Head = 9% Arms = 9% each
– Front & Back Torso = 18% each
– Front & Back of Legs = 18% each
– Genital Region = 1%
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RULE OF NINES Dermal Wound Healing• Inflammatory—4 signs:
• Swelling
• Redness
• Pain
• Itching
• Migratory—blood clot forms & becomes a scab
• Proliferative—lots of mitosis to replace damaged cells
• Maturation—scab comes off; epidermis thickness is restored
Infections & Allergies
• Athlete’s foot—fungal infection
• Contact dermatitis
• Psoriasis
Disorders of the integumentary system
• Cancer – associated with UV exposure; caused by overproduction of certain skin cells
– Basal cell carcinoma- cells of stratum basale
– Melanoma: most dangerous (ABCD)• Asymmetry
• Border irregularity
• Color change
• Diameter larger than 6 mm
Basal cell carcinoma
Sqaumous cell carcinoma
Melanoma
Skin Cancer
ABCD: Danger Signs of Melanoma
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• Dear 16-year Old Me