Download Integumentary System

Integumentary System
Integumentary System - Function
We often don't think of the skin as a complex organ, but it is. The skin is
the primary organ in the integumentary system, which also includes
hair, nails, and certain glands. The integumentary system helps to
provide support and structure for the body, but it also plays several
other important roles:
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It is the first line of defense against foreign organisms and the
external environment.
It helps to regulate body temperature.
It senses changes in the environment (pain, pressure, touch).
It supports the removal of wastes (as sweat).
It aids in the production of vitamin D.
The integumentary system is one of the most active parts of our body,
even though we are not as aware of its activity as we are with the heart,
lungs or stomach. The integumentary system encapsulates and protects
the body. The skin is actually the largest organ in the body because of its
large surface area. In some ways, the skin can be thought of as an
immune system organ, since it protects the body from foreign
organisms. In other ways the skin can be thought of as a sensory organ
because it contains many nerves that are related to the sense of touch.
The skin also integrates with muscles and allows for movements such as
facial expression.
Integumentary System - Organs and Structures
If we take a closer look at the skin, you can see that there are many
layers. Within the skin there are hair follicles from which hair grows.
Also, there are sweat glands that produce sweat for thermal regulation
of the body and sebaceous glands that secrete oil to waterproof and
moisturize the skin. Nails are also included in the integumentary
system, as are horns; feathers, claws and hooves...but hopefully you
don't have any of those.
The major structures within the integumentary system are:
Skin
• Hair, nails
• Sebaceous glands
• Sweat glands
Skin, the largest organ of the body, is the primary organ of the
integumentary system. Skin is composed of three main layers, each of
which has specific functions related to its structure. The three main
layers of the skin are:
• Epidermis, which acts as a seamless, waterproof barrier to the
external environment and prevents excessive water loss from the
body (the root "epi-" means "above").
• Dermis, which provides the tensile strength and elasticity of the skin,
contains nerves and sensory receptors and contains blood vessels
that aid in regulating body temperature.
• Hypodermis, which attaches skin to other structures below it and acts
as an insulator and shock absorber (the root "hypo-" means
"below"); the hypodermis is also known as the subcutaneous layer.
Hair, another component of the integumentary system, is found in
nearly all regions of the skin, except on the palms, soles of the feet, and
some parts of the genitals. Hair grows from hair follicles that are part of
the epidermis, even though they extend down and the dermis extends up
around them. Hair helps regulate body temperature and protect the
surface of the body, including eyelashes that protect the eyes.
Nails are located on the end of each distal phalanx (each finger and each
toe). They protect the phalanges from trauma, and provide mechanical
support for manipulating objects. Nails grow from epidermal cells in the
nail beds.
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Glandular structures are also part of the epidermis, and are present in
different regions of the skin. They secrete substances that are important
for many physiological functions. There are three main types of glands:
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whose secretions maintain the softness and
hydrophobicity (water repellency) of the hair and skin.
Apocrine glands, whose secretions moisten the skin during pain, fear,
sexual arousal and emotional upset.
Sebaceous
glands,
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merocrine (eccrine) glands,
which secrete sweat to regulate body
temperature.
Integumentary System - Anatomy and Direction
The skin covers the outside surface of the body. Special structures such
as hair, nails and glands are part of the integumentary system.