Q: A person is exposed to sunlight, which triggers a chemical reaction in the skin. What is the equation for the synthesis of vitamin D3 from 7-dehydrocholesterol?

$$7\text{-dehydrocholesterol} + UVB \rightarrow \text{cholecalciferol (vitamin D3)}$$

Question 1

Which type of cell is the most abundant in the epidermis and is primarily responsible for producing keratin?

Accepted Answer

Keratinocytes

Question 2

A patient presents with a genetic disorder that prevents the production of melanin. Which epidermal cell type is most likely affected?

Accepted Answer

Melanocytes

Question 3

Which vitamin is synthesized in the skin when exposed to UV radiation and is essential for calcium and phosphorus absorption?

Accepted Answer

Vitamin D3

Question 4

The skin consists of two major layers. Which is the deeper layer?

Accepted Answer

Dermal layer

Question 5

Which of the following is a primary function of the integumentary system?

Accepted Answer

Prevention of water loss

Question 6

A patient receives a subcutaneous injection. In which layer of the skin is the medication delivered?

Accepted Answer

Hypodermis (subcutaneous layer)

Question 7

In which layer of the epidermis do cells stop dividing and begin producing large amounts of keratin?

Accepted Answer

Stratum granulosum

Question 8

Which of the following is NOT considered an appendage of the skin?

Accepted Answer

Adipose tissue

Question 9

Which glands are responsible for producing true sweat and play a major role in thermoregulation?

Accepted Answer

Merocrine (eccrine) glands

Question 10

Activation of the arrector pili muscles results in secretion from which type of gland?

Accepted Answer

Sebaceous glands

Question 11

A patient presents with excessive oiliness of the skin, especially on the face. Which gland is most likely overactive?

Accepted Answer

Sebaceous gland

Question 12

Which layer of the dermis contains the majority of the skin’s sensory receptors and is composed of areolar tissue?

Accepted Answer

Papillary layer

Question 13

Which of the following best describes the composition and function of the hypodermis?

Accepted Answer

Areolar and adipose tissue; provides insulation and energy storage

Question 14

Which type of sweat gland is most numerous on the palms and soles and is important for regulating body temperature?

Accepted Answer

Merocrine (eccrine) gland

Question 15

Which of the following structures is derived from the stratum corneum and serves a protective function for the distal phalanges?

Accepted Answer

Nail

Question 16

A person is exposed to sunlight, which triggers a chemical reaction in the skin. What is the equation for the synthesis of vitamin D3 from 7-dehydrocholesterol?

Accepted Answer

$$7	ext{-dehydrocholesterol} + UVB ightarrow 	ext{cholecalciferol (vitamin D3)}$$

Question 17

Which layer of the epidermis is only found in thick skin, such as the palms and soles?

Accepted Answer

Stratum lucidum

Question 18

Which of the following best explains why apocrine sweat glands contribute to body odor?

Accepted Answer

They release lipids and proteins that are metabolized by skin bacteria

Question 19

A burn patient loses the entire epidermis and part of the dermis. Which functions of the integumentary system are most compromised?

Accepted Answer

Protection against pathogens and prevention of water loss

Question 20

Which equation best represents the relationship between skin surface area ($$A$$), sweat rate ($$Q$$), and heat loss ($$H) $$during thermoregulation?

Accepted Answer

$$H = Q 	imes A$$

The Integumentary System: Structure and Function

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