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This chapter should help the student to:

  • List the skin’s functions and relate them to its structure.

  • Name the skin’s two major layers. For each, name the basic tissue type that predominates and describe the arrangement and distinguishing features of its constituent layers.

  • Name the four cell types of the epidermis and describe their structure, function, and location.

  • Relate the steps in cell renewal and keratinization to the epidermal layers.

  • Compare and contrast thick and thin skin.

  • Describe melanin granule synthesis and turnover.

  • Identify and describe the components of hair follicles and nail complexes. Briefly describe nail and hair growth.

  • Describe the skin’s blood and nerve supply in terms of structure, function, and location.

  • Name and compare three types of glands in skin in terms of structure, function, and location.

  • Identify skin type, layers, cell types, hair follicles, and glands in a micrograph of a section of skin.


  1. Name the two major layers of the skin (I.B1) and compare them in terms of thickness (I.B.3; Fig. 18–1), vascularity (I.B.1 and 3), and embryonic germ layer of origin (I.B.1 and 3).

  2. Describe the hypodermis in terms of its structure, function, and location (I.B.4).

  3. List the four cell types in the epidermis and compare them in terms of their relative number, location, and primary function (II.A, B.2, C, and D).

  4. Compare thick and thin skin in terms of epidermal layers, number of hair follicles, sweat glands and sebaceous glands, and location (Table 18–1).

  5. Beginning at the surface, list the five layers of the epidermis (II.A.1–5). Compare the keratinocytes in each layer in terms of their cell shape, capacity for cell division, staining properties, and the visibility of their nuclei and other organelles.

  6. Compare the structures binding the keratinocytes and melanocytes in the stratum basale to the underlying basal lamina (II.A.1 and B.2).

  7. Name the embryonic cell type that forms melanocytes (II.B.2).

  8. Name the enzyme in melanocyte granules that is primarily responsible for melanin production (II.B.3).

  9. Describe how melanin granules enter keratinocytes (II.B.4).

  10. Name two mechanisms that darken the skin after ultraviolet light exposure (II.B.6).

  11. Describe Langerhans’ cells (II.C) in terms of their shape, location, staining properties, granules, and immune function.

  12. Describe Merkel’s cells (II.D) in terms of the skin type (thick or thin) in which they are most abundant, their association with nerve endings, and two possible functions.

  13. Name the two layers of the dermis (III.A and B) and compare them in terms of their primary tissue type, thickness, and location in relation to the epidermis and hypodermis.

  14. Is hair growth continuous or discontinuous? Explain the expression “growth in mosaic” (V.D).

  15. Sketch a hair follicle in longitudinal section (V.B.1–4; Fig. 18–3). Include and label the following:

    1. Hair bulb

    2. Dermal papilla

    3. Germinal matrix

    4. Melanocytes

    5. Hair shaft

    6. Internal root sheath

    7. External root sheath

    8. Glassy membrane

    9. Connective tissue sheath

    10. Arrector pili muscle

  16. Sketch a cross-section through a hair follicle above the bulb ...

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