The Integumentary System
Sweat Glands
- Sweat glands are most numerous in the palms of our
hands and in the soles of our feet.^
- The secretory, blind tube portion of a sweat gland is in
the subcutaneous tissue. The excretory portion goes
through the dermis to the surface.^
- The odor of sweat is produced by the action of
bacteria- feeding on the sweat.^
- Sweating is an important physiologic process that
helps cool the body.
Functions Of The Integumentary
System
- The skin functions in sensation, protection, thermo-
regulation, and secretion.
Sensation
- Receptor sites for changes in temperature (hot and
cold) and pressure (pleasure and pain) are found in the
skin.^
- Combinations of stimulations result in the sensa-
tions of itching, burning, and tickling.
Protection
- The skin prevents the entrance of harmful physical
and chemical agents into the body.^
- Melanin protects us from the harmful ultraviolet
rays of^ the sun.^
- The lipid content of skin prevents excessive water
and electrolyte loss.^
- The acidic pH of skin kills most bacteria and
microorganisms- that come in contact with our
skin.^
- Hair acts as an insulator, protects our eyes, and
filters- out foreign particles in our nose.
Thermoregulation
- Normal body temperature is regulated by blood
vessel dilation and constriction in the dermis of
the skin.^
- Sweating is an evaporation process that cools
the body.
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Secretion- Sebum has antifungal and antibacterial
properties.^ - Sweat contains waste products such as urea, uric
acid, and ammonia, so it is also an excretion.^ - The skin manufactures vitamin D through exposure to
ultraviolet rays of the sun.
Review Questions
- List the five layers of the epidermis with their
common names.^ - List and describe four functions of the integumen-
tary system.^
3. If all people have the same number of melanocytes in
their skin, how do we explain the differences in color
among the various races?^
4. Why would a person born with an absence of sweat
glands be very susceptible to death by expo-sure to
heat?
*Critical Thinking Questions
Search and Explore
● Visit the Skin Cancer Foundation
website- at http://www.skincancer.org
and research- one of the types of skin
cancer. Write a short paper of one to
two paragraphs- about what you
learned.● Visit the MedlinePlus website at http://
http://www.nlm.nih.gov/medlineplus and
search on any of the skin conditions
mentioned in this chapter.