Download Integumentary system is the skin and the organs derived from it (hair

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
2. Protection
physical abrasion
dehydration
ultraviolet radiation
3. Sensation
touch
vibration
pain
temperature
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
•  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.
•  Multiple layered arrangement of
cuboidal cells
•  Are spiny or prickly in appearance,
due to molecular bridges that
connect them to other cells
•  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
• 
• 
• 
• 
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 moves into the
stratum cornuem by osmosis and causes
wrinkles in the skin
•  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.
•  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
•  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
•  2 areas
•  Superficial
area adjacent
to epidermis
called
papillary
region
•  Deep thicker
area 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.
•  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
•  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