Anatomy and Physiology
Chapter 6: Skin and Integumentary System
Fisher
Critical Thinking Questions, p. 124 #’s 1-7
1. Everyone’s skin contains about the same number of melanocytes even though
people are of many different colors. How is this possible?
Melanocytes produce differing amounts of melanin and different sized
granules of melanin. This is based on both genetics and environmental
conditions. The amount of melanin and its distribution determine skin color.
Melanin can travel via cytoplasmic extensions through a process called
cytocrine secretion. This carries melanin to more superficial layers of the
epidermis. (p. 116)
2. Why would collagen and elastin added to skin creams be unlikely to penetrate
the skin—as some advertisements imply they do?
These fibers are too large to penetrate the epidermis—which is made up of
various strata, the outermost layer being keratinized to protect against water
loss and infection. In order to change the skin they would need to be present in
the dermis, and topically applied they will not reach the dermis. (P. 114)
3. A severe form of the inherited illness epidermolysis bullosa causes extreme
blistering of the skin. The person lacks a protein called laminin, which
normally attaches the dermis to the epidermis. Explain how lack of this protein
disrupts the skin’s structure.
Without the protein that binds the epidermis to the dermis (basement
membrane) the structure of the skin and therefore the skin’s integrity is
compromised. This means the epidermis may not completely cover the dermis
in places, providing gaps in this coverage. As the dermis contains vessels that
supply the epidermis, and the deep layers of the epidermis do not keratinize, the
protection is incomplete and blistering occurs—there could be potential
bleeding, loss of moisture in general from the skin, and avenues for infection
from these openings. If the epidermis is damaged for any reason, because the
blood source is in the dermis, then healing would be slow. More blood and
lymph may attempt to get to the site, but there may be difficulties with this.
This may cause more fluid to be expelled, slower healing may also encourage
further infection.
4. How is skin peeling after a severe sunburn protective?
The damaged cells die and are shed, for new epidermal cells to take their place.
This lowers the risk of DNA mutations that can cause cancer. (pp. 119, 121)
5. What special problems would result from the loss of 50% of a person’s
functional skin surface? How might this person’s environment be modified to
compensate partially for such a loss?
The loss of fluids is significant, the ability of the person to protect against the
loss of fluids in the future is also significant. A person will generally need to
have skin grafted or a skin substitute applied in order to survive. Oil and
sweat may not be produced or produced as well in the effected area—so cooling
the environment and moisturizing may be of critical import to the individual
in the future, as well.
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modified 2/15/2016
Anatomy and Physiology
Chapter 6: Skin and Integumentary System
Fisher
6. A premature infant typically lacks subcutaneous adipose tissue. Also the
surface area of an infant’s small body is relatively large compared to its
volume. How do you think these factors affect the ability of an infant to
regulate its body temperature?
The infant will have trouble retaining body heat, due to the lack of
subcutaneous fat and large surface area. The increased surface area allows
heat to dissipate quickly from the body. IN addition infants have higher heart
rates and blood moves quickly throuout.
7. Which of the following would result in the more rapid absorption of a drug: a
subcutaneous injection or an intradermal injection? Why?
Subcutaneous to get to the blood vessels quicker and travel throughout the
body.
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modified 2/15/2016