I. Introduction
A. Organs are composed of two or
more kinds of tissues
B. Largest organ of the body is the
skin (“Integumentary System”
includes hair, nails, and skin)
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II. Functions of the Integumentary System
A. Protection
B. Regulates body temperature
C. Slows water loss
D. Houses sensory receptors
E. Manufactures biochemicals
F. Excretes waste
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III. Four Types of Membranes
A. Serous Membranes
• Composed of two layers of tissue
- epithelial sheet (SSE)
- basement membrane (support)
• Serous membrane that lines walls
of body cavities: parietal portion
• Serous membranes that cover surface
of organs: visceral portion
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Serous membranes: secrete a thin,
watery fluid that helps reduce friction
and serves as lubricant when organs
rub against one another
Thoracic cavity: “pleura/pericardium”
Abdominal cavity: “peritoneum”
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B. Mucous membranes
• epithelial membranes that line body
surfaces opening directly to the
exterior
• cells secrete thick, slimy material that
keeps membranes moist and soft
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Mucous Membranes
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Respiratory
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Mucous Membrane
Digestive System
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Mucous Membrane
Female Reproductive
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Mucous Membrane
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Male Reproductive
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Mucous Membrane
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Female Urinary
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Mucocutaneous junction
• transition areas where skin and mucous
membrane meet
• generally moistened by mucous glands
within body orifices or openings
examples: eyelids, nasal openings,
vulva, anus
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C. Synovial membranes
1. Line joint cavities
2. Secrete a “synovial fluid” that
lubricates the ends of the bones
at joints (the Tinman in the “Wizard
of Oz”)
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Synovial Membrane
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D. Cutaneous membrane
• Primary organ of integumentary
system
• Consists of superficial layer of
epithelial cells and underlying
structure of supportive connective
tissue (our “skin”)
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IV. Layers of the Integumentary System
A. Epidermis (“upon + skin”)
1. Deepest layer contains cells that
divide (Strat. Squam. Epith.)
2. Keratinization: process by which
cells mature (changing shape and
size) as they move from
deepest to most superficial layer
3. Outermost layer is made up of
dead epidermal cells
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4. Epidermis protects underlying tissues
from water loss, injury and harmful
chemicals
5. The pigment “melanin” protects
underlying cells from UV rays
6. Melanocytes (black + cells) transfer
melanin to nearby epidermal cells
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B. Skin color (Pigments in the Epidermis)
1. All folks have about same
concentration of melanocytes
2. Amount of melanin, distribution
and size of pigment granules in
epidermis determine skin color
3. Skin color also influenced by
environment, physiological factors
and genetics
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C. Dermis
1. Function: connects epidermis to
underlying connective tissue
2. Blood vessels in derma supply
nutrients to skin cells and help
regulate body temperature
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3. Nerve fibers located throughout dermis
a. somatic: control glands, muscles
b. sensory: send messages to brain
4. Contains hair follicles, sebaceous
(oil) glands and sweat glands
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D. Hypodermis (“below + skin”)
Subcutaneous (“below + skin”)
1. Loose connective and adipose tissue
2. Helps conserve body heat
3. Contains blood vessels that supply
skin and underlying adipose tissue
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V. Accessory Skin Structures
A. Hair follicle
1. Cells from which hair originates
2. Keratinization occurs
3. Bundle of smooth muscle is
attached to each hair follicle
(arrector pili muscle: contracts
and causes goose bumps to form)
4. Hair color is determined by amount
melanin production
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B. Sebaceous glands
1. Share pore with hair follicle
2. Secrete oil or “sebum” which keeps
hair and skin soft/waterproof
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C. Nails
1. Protective covering produced by
epidermal cells and cover terminal ends
of fingers and toes
2. Nails: keratinized epidermal cells
3. Keratin in nails is harder than the
keratin produced by the skin’s
epidermal cells
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D. Sweat glands
1. Functions: cooling and excrete waste
products
2. Eccrine (Merocrine) sweat glands:
respond to elevated body temperature
3. Apocrine sweat glands: respond to
emotional stress (Absolutely Awful
Adolescent odor)
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VI. Regulation of Body Temperature
A. Body temperature rises:
dermal vessels dilate, merocrine glands
secrete sweat
B. Body temperature drops: dermal vessels
constrict and sweat glands become
inactive
C. Excessive heat loss: skeletal muscles
contract involuntarily (“shivering”)
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D. Fever is elevated temperature
“If you are sick, do you have a
temperature? If you are well,
do you have a temperature?”
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VII. Healing of Wounds
A. Reproducing epithelial cells
fill in the shallower cuts
B. Blood clots fill deeper cuts,
sometimes leave a scar
C. Granulations form as part of
the healing process
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