Download 36.3 – The Integumentary System

36.3 – The Integumentary System
Regents Biology
Integumentary System
  The skin, hair,
nails, and a variety
of glands make up
the integumentary
system.
  The skin is the
largest organ in the
body.
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Functions
  serves as a barrier
against infection and
injury
  helps to regulate body
temperature
  removes waste
products from the
body
  provides protection
against ultraviolet
radiation from the sun
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The Skin
  made up of two main
layers:
- epidermis (dead outer
layer, living inner
layer)
- dermis
  Beneath the dermis is a
layer of fat (hypodermis)
and loose connective
tissue that insulates the
body.
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Nerves
Sweat pore
Hair follicle
Blood
vessels
Hair
Sebaceous
gland
Epidermis
Dermis
Muscle
Sweat
gland
Hypodermis
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Fat
  Cells in the inner (living) layer
undergo rapid cell division,
producing new cells that push
older cells to the surface of the
skin.
  Older cells flatten and their
organelles disintegrate.
  Older cells make keratin (a fibrous
protein). When these cells die,
they form a waterproof covering
on the skin’s surface.
  The epidermis also produces
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melanin (brown skin pigment).
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The Dermis
  inner layer of the skin
  contains collagen
fibers, blood vessels,
nerve endings, glands,
sensory receptors,
smooth muscles, and
hair follicles
  contains two major
types of glands (sweat
glands and sebaceous
(or oil) glands
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Cooling and Excretion
  When sweat evaporates, it cools the body.
  Sweat also gets rid of wastes from the blood, along
with water.
  Sebaceous glands produce an oily secretion called
sebum.
  Sebum spreads out along the surface of the skin and
helps to keep the skin flexible and waterproof.
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Hair and Nails
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Hair
  Hair covers most body surfaces.
  Hair protects the scalp from
ultraviolet light from the sun,
provides insulation from the cold,
and prevents dirt and other
particles from entering the body.
  Hair is produced by hair follicles
(tube-like pockets of epidermal
cells).
  An individual hair is a column of
cells that have filled with keratin
and died.
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Nails
  Nails grow from rapidly dividing cells in the nail root.
  The nail root is located near the tips of the fingers
and toes.
  During cell division, cells fill with keratin and produce
a plate-like nail that covers and protects the
fingertips and toes.
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