Unit
Review
Here is what we have learned from this unit:
- The skin is a vital organ that covers the entire outside of the body,
forming a protective barrier against pathogens and injuries from the
environment. The skin is the body's largest organ; covering the entire
outside of the body, it is about 2 mm thick and weighs approximately
six pounds.
- The skin helps regulate body temperature, gathers sensory information
from the environment, stores water, fat, and vitamin D, and plays a role
in the immune system protecting us from disease.
- The color, thickness and texture of skin vary over the body. There
are two general types of skin; thin and hairy, which is more prevalent
on the body, and thick and hairless, which is found on parts of the body
that are used heavily and endure a large amount friction, like the palms
of the hands or the soles of the feet.
- Basically, the skin is comprised of two layers that cover a third
fatty layer. These three layers differ in function, thickness, and strength.
- The outer layer is called the epidermis; it is a tough protective layer
that is made up of five sublayers that work together to continually rebuild
the surface of the skin.
- The second layer of the skin (located under the epidermis) is called
the dermis; it contains collagen and elastin, blood vessels, lymph vessels,
nerve endings, sweat glands, sebaceous (oil) glands, and hair follicles.
- The innermost layer of the skin is a fatty layer of subcutaneous tissue
consisting of a network of fat and collagen cells and is known as the
subcutis or hypodermis.
- The basal cell layer of the epidermis contains melanocytes. Melanoma
develops when melanocytes undergo malignant transformation.
- The stratum corneum is the outermost layer of the epidermis, and is
made up of thin layers of continually shedding, dead keratinocytes. The
stratum corneum is also known as the “horny layer,” because
its cells are toughened like an animal’s horn. As the outermost
cells age and wear down, they are replaced by new layers of strong, long-wearing
cells.
- Regional lymph nodes for melanoma of the skin vary by primary site,
and are bilateral or contralateral for the primary sites of head, neck
and trunk.
![](images/icon_unit_review_match.gif)
Number-Term
Match Quiz
It's time to see how much you have learned from this unit. You are going
to take a number-term match quiz, in which, by studying an illustration with
a numbered anatomical structure, you type correct numbers into input fields
to match anatomical terms. When you finish all the questions, click the "Check
Answers" button to see the result.
Please click here to take
the quiz.
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