Chapter 5 Integumentary System

Thin skin has four layers, but thick skin has five. Which layer of the epidermis is only found in thick skin?

• Stratum basale

• Stratum corneum

• Stratum lucidum

• Stratum granulosum

True or false: The skin resists and recovers from trauma better than other organs do

• False

• True

Which layer of the epidermis is the deepest, consisting of a single layer of stem cells, keratinocytes, melanocytes, and tactile cells?

• Stratum corneum

• Stratum lucidum

• Stratum spinosum

• Stratum granulosum

• Stratum basale

Which layer of the epidermis is the thickest, consisting of many layers of keratinocytes and dendritic cells?

• stratum spinosum

• Stratum lucidum

• Stratum basale

• Stratum granulosum

Answer explanation

This level consists of many layers of large keratinocytes interspersed with dendritic cells. As keratinocytes are pushed upward by dividing cells below, they cease dividing and synthesize keratin. Keratin accumulation causes the cells to flatten and assume a squamous shape.

How much of the average person's body weight is accounted for by their skin?

• 15%

• 45%

• 75%

• 12%

Answer explanation

The skin covers the entire body surface—up to 2 m^2 in adults, and accounts for about 15% of the body weight.

Which cell type of the epidermis probe it for toxins and infections?

• stem cells

• keratinocytes

• melanocytes

• dendritic cells

Answer explanation

Dendritic cells, scattered among the keratinocytes, probe the epidermis for foreign matter such as toxins and infections and alert the immune system when there is a need to defend the body against invaders.

Which layer of the epidermis consists of three to five layers of flat keratinocytes with course, dark-staining granules?

• Stratum basale

• Stratum lucidum

• Stratum granulosum

• Stratum corneum

• Stratum spinosum

Answer explanation

This consists of three to five layers of flat keratinocytes with coarse, dark-staining granules. Keratin filaments in these cells clump together into thick bundles that toughen the epidermis, while the cells become coated with lipid that produces a barrier to water. This is one reason the skin inhibits water loss from the body. The cells die here as the protein barrier cuts them off from nutrients from below.

Put the layers of the epidermis in order. Start with the deepest layer and end with the most superficial layer.

• stratum corneum, Stratum granulosum, Stratum basale, Stratum lucidum

• Stratum basale, Stratum spinosum, Stratum granulosum, Stratum lucidum, stratum corneum

• Strutum spinsoum, Stratum basale, Stratum granulosum, Strayum lucidum

• Stratum basale, Stratum lucidum, stratum granulosum

The stem cells of the stratum basale layer of the epidermis produce which of the following?

• Keratinocytes

• Immune cells

• Melanocytes

• Tactile cells

Tags

NGSS.HS-LS1-4

The stratum lucidum layer is only present in (a)   skin.