Living things have their own “fences”
and none is as important as the skin –
the boundary that separates the
human body from the outside world.
“SKIN” - the single largest organ in the
What does the word integument means?
-it comes from a Latin word that means to
cover, reflecting the fact that the skin and
its accessory structures form a covering
over the entire body.
The skin and its
accessory organs ---
the hair, nails and a
variety of glands.
What is the most important function of the
It performs this function by acting as a
barrier against infection and injury; helping
to regulate body temperature; removing
waste products from the body; and
providing protection against ultraviolet
radiation form the sun.
Because the main component of the
integumentary system, the skin, contains
several types of sensory receptors, it
serves as the gateway through which
sensations such as pressure, heat, cold,
and pain are transmitted to the nervous
Epidermis is the outermost layer of the skin.
Most of the cells of the epidermis undergo
rapid cell division (mitosis). As new cells
are produced, they plush the older cells to
the surface of the skin. Here are the older
cells become flattened, lose their cellular
contents. And begin making keratin.
What is keratin?
- a tough fibrous protein
In humans, it forms the basic structure of
hair, nails, and calluses. In other animals,
keratin is more versatile --- forming cow
horns, reptile scales, bird feathers, and
Keratinocytes, the keratin-producing
cells, die and form a tough, flexible
waterproof covering on the surface of the
skin. This outer layer of dead cells is shed
or washed away at a surprising rate – once
over 14 to 28 days.
The epidermis also contains
melanocytes, or cells that produce melanin,
a dark pigment. Although light-skinned and
dark-skinned people have roughly the
same number of melanocytes, the
difference in their skin color is caused by
the amount of melanin the melanocytes
produce and distribute. There are no blood
vessels in the epidermis, which explains
why a slight scratch will not cause bleeding.
What is dermis?
It is the innermost layer of the skin. It lies
beneath the epidermis and contains blood
vessels, nerve endings, glands, sense
organs, smooth muscles, and hair follicles.
How does our body
adopt during hot and
When the body needs to conserve heat
on cold day, the blood vessels in the dermis
narrow, helping to limit heat loss. On hot
days, the blood vessels widen, warming the
skin and increasing heat loss. Beneath the
dermis is the hypodermis, a layer of fat
and loose connective tissue that insulates
What are the two major
types of glands contained
in the dermis?
Sweat glands and Sebaceous or oil glands
These glands pass through the epidermis
and release their products at the surface of
the skin. Sweat glands produce the watery
secretion known as sweat, which contains
salts, water, and other compounds.
These secretions are stimulated by nerve
impulses that cause the production of
sweat when the temperature of the body is
raised. Sebaceous glands produce an oily
secretion known as sebum that spreads out
along the surface of the skin and keeps the
keratin-rich epidermis flexible and
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HOPE YOU’LL ALSO DO THE SAME TO
THE NEXT REPORT…….
HAIR AND NAILS…..