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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