Download The Skin

The
Integumentary
System
Organs of the
integumentary system
skin
hair
nails
Skin
The largest organ in your body
Functions
Covers the body and prevents water loss
Protects the body from injury and infection
Regulates body temperature
Eliminates wastes (sweat)
Produces vitamin D
Gathers information about the environment
Stores fat for fuel and insulation
Prevents Water Loss
Skin prevents water from leaking out of
your body
Prevents Infection
Skins acts as a barrier to bacteria and
viruses
Maintains Homeostasis
Helps to keep the body temperature
normal
Has blood vessels that tell the body
when it is hot or cold
Hot – blood vessels get larger and sweating
occurs
Cold – blood vessels constrict to keep blood
in the body’s core
Eliminates Waste
Sweating eliminates dissolved waste
from your body
Gathers Information
Skin contains nerves that can feel pain
or pressure
Provide Vitamin D
With the help of sunlight, your skin
produces vitamin D
Vitamin D is essential in calcium
absorption from food
Layers of Skin
Skin consists of three main layers
epidermis
dermis
subcutaneous
layer
subcutaneous
layer
Epidermis
 Outermost layer
 30-60 cells thick
 No nerves or blood vessels
 Top layer is dead
 New cells formed at the bottom of this layer
 Skin cells shed every 2 weeks
 Where nails grow
 Contains melanin
Epidermis
 Where nails grow
 Contains melanin
 Every minute, 30,000 - 40,000 skin cells fall off
 95% of your skin cells make new cells
 5% make melanin
 More sun exposure
= more melanin (tan)
Dermis
 Middle layer
 Contains nerves and
blood vessels
 Contains sweat
glands, oil glands
and hair follicles
 Contains collagen
and elastin that
allows skin to
stretch
subcutaneous layer
 Made mostly of fat
 Keeps you warm
 Absorbs shock
 Attaches your skin
to the underlying
tissue
hair
Made of a strong, dead protein, called
keratin
Grows out of a tiny tube called a follicle
Hair growth is caused by rapid mitosis
in the follicle
Hair follicles are everywhere except
lips
palms
soles
hair
Over 100,000 follicles on the scalp
Each follicle is attached to a gland that
secretes sebum (oil)
Color is partially determined by
melanin
nails
Modified hair that grows from your
cuticle
Made of keratin
No nerve endings
Protects the end of fingers and toes
Takes 6 months to grow from cuticle to
tip
nails
Fingernails grow faster than toenails
Nails grow faster on your dominant
hand
Nails DO NOT grow after death
Body systems that work with the
integumentary system;
Send sensory information to the
nervous system, the respiratory
and circulatory system provide
oxygen, the digestive system
provides nutrients and energy,
skin is part of the excretory system