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Ch. 5 The Integumentary System
Hoehn - Marieb Human Anatomy & Physiology, 12th edition
Hoehn, Haynes, Abbott12th EditionMarieb Human Anatomy & PhysiologyISBN: 9780138242732Not the one you use?Change textbook
All textbooksHoehn, Haynes, Abbott 12th EditionCh. 5 The Integumentary SystemProblem 21
Chapter 5, Problem 21

Explain each of these familiar phenomena in terms of what you learned in this chapter:
a. Pimples
b. Dandruff
c. Greasy hair and 'shiny nose
d. Stretch marks from gaining weight
e. Freckles

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1
For pimples, explain how they result from the inflammation of sebaceous (oil) glands in the skin. When these glands produce excess sebum, it can clog hair follicles, trapping bacteria and dead skin cells, which leads to swelling and redness characteristic of pimples.
For dandruff, describe it as the shedding of dead skin cells from the scalp. This occurs when the normal process of skin cell turnover accelerates, often due to irritation or fungal activity, causing visible flakes and sometimes itching.
For greasy hair and a 'shiny nose,' discuss how overactive sebaceous glands produce excess sebum, which coats the hair and skin surface. This oily layer reflects light, giving hair a greasy appearance and skin a shiny look, especially in areas with many sebaceous glands like the nose.
For stretch marks from gaining weight, explain that rapid stretching of the skin causes the dermis (the middle layer of skin) to tear or become damaged. This disrupts collagen and elastin fibers, leading to visible streaks or lines known as stretch marks.
For freckles, describe them as small, concentrated spots of melanin pigment produced by melanocytes in response to UV exposure. Freckles are more visible in individuals with lighter skin and represent localized increases in pigmentation rather than an increase in the number of melanocytes.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Sebaceous Glands and Sebum Production

Sebaceous glands are skin glands that produce sebum, an oily substance that lubricates hair and skin. Overproduction or blockage of sebum can lead to pimples and greasy hair, as excess oil clogs pores and creates a shiny appearance.
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Sebum

Skin Cell Turnover and Flaking

The skin continuously renews itself by shedding dead cells and generating new ones. Dandruff results from an accelerated shedding of skin cells on the scalp, often linked to dryness or fungal activity, causing visible flakes.
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Skin Elasticity and Melanin Production

Skin elasticity refers to the skin's ability to stretch and return to shape; overstretching can cause stretch marks due to collagen fiber damage. Melanin is the pigment responsible for skin color, and its uneven distribution leads to freckles, which are small, concentrated spots of pigment.
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Related Practice
Textbook Question

Mrs. Gaucher received second-degree burns on her abdomen when she dropped a kettle of boiling water. She asked her doctor (worriedly) if she would need a skin graft. What do you think he told her?

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Textbook Question

The rule of nines is helpful clinically in

a. Diagnosing skin cancer

b. Estimating the extent of a burn

c. Estimating how serious a cancer is

d. Preventing acne

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Textbook Question

Why are there no skin cancers that originate from stratum corneum cells?

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Textbook Question

Which epidermal cells contain keratohyaline and lamellar granules?

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