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Integumentary System
Integumentary system is the skin and
the organs derived from it (hair,
glands, nails)
One of the largest organs
2 square meters; 10-11 lbs.
Largest sense organ in the body
The study of the skin is Dermatology
Functions of the Integumentary
system
1. Regulation of body temperature
– Cellular metabolism produces heat as a waste
product .
– High temperature
• Dilate surface blood vessels
• Sweating
– Low temperature
• Surface vessels constrict
• shivering
Additional Functions
2. Protection
physical abrasion
dehydration
ultraviolet radiation
3. Sensation
touch
vibration
pain
temperature
Additional Functions
4. Excretion
5. Immunity/ Resistance
6. Blood Reservoir
8-10 % in a resting adult
7. Synthesis of vitamin D
UV light
aids absorption of calcium
Structure
Epidermis Structure
Stratum Basale
• Deepest layer
• Columnar cells capable of continued cell division.
• Newly made cells get pushed to surface where there
is less blood supply and they begin to die.
Stratum spinosum
• Multiple layered arrangement of
cuboidal cells
• Are spiny or prickly in appearance,
due to molecular bridges that
connect them to other cells
Stratum granulosum
• 3-5 rows of flattened cells
• Cytoplasm of cells contain granules
• The granules are protein that
transforming into waterproofing
protein keratin (process starts)
• Cells begin to die
Stratum lucidum
• Present in only the thick skin of palms
of hands and soles of feet
• 3-4 rows of flattened dead cells
(Transparent)
• Process of keratin formation continues
here
Stratum corneum
•
•
•
•
Most superficial
20-50 rows flattened dead cells
Cells are “sloughed off” by normal wear
Each cell contain keratin, protects skin from
water loss
• When skin is exposed to water for long
periods of time the water in skin moves
outward by osmosis and causes wrinkles in
the skin
Skin Color- Melanocytes
• Determined by cells in between the dividing cells
of the Stratum basale.
• Secrete a dark colored pigment called melanin
• Greater amount melanin the darker the skin
• Regulated by DNA but can be altered by UV light,
prolonged exposure can increase the melanin
secretion and darken the skin (Tanning)
• Function of Melanocytes- protection from UV
light.
Skin Color - Carotene
• Pigment
• Present in the Stratum corneum and dermis
• Most present in people with Asian origin,
gives a yellow hue
• Pinkish color of Caucasian people is
attributed to small amounts of melanin and
carotene, influenced by blood in blood
vessels
Dermis- Overview
• Region of connective tissue, located deep to
the epidermis.
• Scattered apart unlike the epidermis
• Contains a large amount of collagen
• Blood vessels extend through to the stratum
basale
Dermis - Structure
• 2 areas
• Superficial
area adjacent
to epidermis
called
papillary
region
• Deep thicker
area reticular
region
Dermis- reticular region
• Deep to the papillary region and is much thicker
• Composed of dense irregular connective tissue
• Named for the collagenous, elastic and reticular
fibers
• These fibers give the dermis, strength,
extensibility, and elasticity
• Wrinkles occur because of a change in these fibers
• The accessory organs are located here.
Dermis- papillary region
• Composed of loose (areolar) connective tissue.
• Named for finger like projections called papillae,
that extend into the epidermis.
• Papillae provide the dermis with a bumpy surface
that strengths the connection between the dermis
and the epidermis.
• In the palms, fingers, soles and toes they form
contours in the skin called friction ridges.
• Friction ridges occur in patters that are genetically
determined. (Fingerprints)
Accessory Organs- Hair
• Protects the skin from injury from sunlight
and other particles
• Supported by the epithelial cells- Hair
follicle
• 2 portions – root-part surrounded by the
follicle, shaft-extends away from the body
surface
• Bulb- the place where the the hair gets
nutrients
Hair Growth
• Similar to skin growth, old cells get pushed
up to the surface.
• Developing cells located in the bulb
• The shaft is made up of dead cells
• Normal rate of growth 1mm every 3 days
Associated with hair follicles:
• Arrector pili- small narrow band of smooth muscle
that extends at an angle from the follicle to the
papillary region.
• The contraction of this muscle causes the hair to
stand up, like when cold of scared
• The contraction of this muscle causes a small
amount of heat, and the contraction of many of
those muscles causes “goose bumps”
Sebaceous Glands
• Oil glands
• Consists of cluster of glandular epithelial
cells, connected to a hair follicle by a duct
• Not located on the palms and soles
• Secrete sebum- used to keep hair and skin
soft and pliable, a water resistant layer
Sweat Glands
• Sudoriferous glands – secrete watery
substance called sweat.
• Helps maintain body temperature body
temperature
• Pore- opening to the skin surface
• 2 types of glands- eccrine-function
throughout life and distributed throughout
the body, apocrine- function during puberty
and respond to production of sex hormone
• Compressed
outer layer
of the
epidermis
• Composed
of keratin
• Protect ends
of fingers
and toes,
help pick up
small
objects, and
grip the
floor
Nails
Nail root
Nail body
Receptors
• Consists of the distal ends of nerve cells wrapped
in a capsule of connective tissue
• Carry impulses to the brain
• Interpretation of sensation takes place, hot cold,
pressure, pain and fine touch
• Two types of receptors
-Pacinian corpuscles- sense pressure changes
-Meissner’s corpuscles- sense slight pressure
change- light touch
Others respond to pain and temperature changes
Hypodermis
• Not usually considered a component of skin organ
• Deep region of the dermis, connects to underlying
body structures, by way of collagen
• Composed of adipose tissue and loose connective
tissue
• Varies in thickness over the body
• Insulates deep tissue from temp changes, shockabsorbing cushion and reserved for energy storage
Homeostasis
• Skin plays a key role in regulating
temperature
– Cellular metabolism produces heat as a waste
product .
– High temperature
• Dilate surface blood vessels
• Sweating
– Low temperature
• Surface vessels constrict
• shivering
Skin Repair
• Steps in wound healing:
1. Bleeding as a result of damage to blood vessels
in dermis. Inflammation of tissue surrounding ,
brings phagocytic cells (White blood cells) to
site.
2. Establishment of clot (Scab)- epithelial cells
migrate around the scab and reproduce.
3. Continued epithelial reproduction and
production of new intercellular material in the
dermis.
4. Replacement of scab with scar tissue