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The skin is the soft outer covering of vertebrates that guards the underlying muscles, bones, ligaments, and internal organs.
Identify the functions of cutaneous membranes
The outer layer of skin, the epidermis, provides waterproofing and serves as a barrier to infection.
The middle layer of skin, the dermis, contains blood vessels, nerves, and glands that are important for our skin's function. The inner layer of the skin, the subcutis, contains fat that protects us from trauma.
The cutaneous membrane is the technical term for our
skin. The skin’s primary role is to help
protect the rest of the body’s tissues and organs from physical damage such as
abrasions, chemical damage such as detergents, and biological damage from microorganisms. For example, while the skin harbors many
permanent and transient bacteria, these bacteria are unable to enter the body
when healthy, intact skin is present.
Our skin is made of three general layers. In order from most superficial to deepest they
are the epidermis, dermis, and subcutaneous tissue.
The epidermis is a thin layer of skin. It is the most superficial layer of skin, the layer you see with
your eyes when you look at the skin anywhere on your body. Functions of the epidermis include touch sensation and protection against microorganisms.
This skin is further divided into
five, separate layers. In order from most superficial to deepest, they are the:
This layer is composed of the many dead skin cells that you shed into the
environment—as a result, these cells are found in
dust throughout your home. This layer helps to repel water.
layer is found only on the palms of the hands, fingertips, and the soles of the
This is the layer where part of keratin production occurs. Keratin is a protein that is the main
component of skin.
This layer gives the skin strength as well as flexibility.
is where the skin’s most important cells, called keratinocytes, are formed
before moving up to the surface of the epidermis and being shed into the
environment as dead skin cells.
layer also contains melanocytes, the cells that are largely responsible for
determining the color of our skin and protecting our skin from the harmful
effects of UV radiation. These harmful
effects include burns in the short term and cancer in the long run.
Underneath the epidermis lies the dermis. The dermis contains:
Blood vessels that nourish the skin with oxygen and nutrients. The blood vessels also allow immune system cells to come to the skin to fight an infection. These vessels also help carry away waste products.
Nerves that help us relay signals coming from the skin. These signals include touch, temperature, pressure, pain, and itching.
Collagen, a protein that is responsible for giving skin strength and a bit of elasticity.
The deepest layer of the skin is called the subcutaneous
layer, the subcutis, or the hypodermis. Like
the dermis, the layer contains blood vessels and nerves for much the same
Importantly, the subcutis
contains a layer of fat. This layer of
fat works alongside the blood vessels to maintain an appropriate body
temperature. The layer of fat here acts
as a cushion against physical trauma to internal organs, muscles, and bones.
Additionally, the body will turn to this fat in times of starvation to provide
power to its various processes, especially brain function.