Q: Which equation correctly represents the initial step in Vitamin D synthesis in the skin?

$7\text{-dehydrocholesterol} \rightarrow \text{cholecalciferol (Vit. D}_3)$

Question 1

Which pigment is primarily responsible for protecting the skin from ultraviolet (UV) radiation damage?

Accepted Answer

Melanin

Question 2

A patient presents with yellowing of the skin and eyes. Which of the following is the most likely cause?

Accepted Answer

Elevated bilirubin due to liver dysfunction

Question 3

During vigorous exercise, why does the skin appear more red?

Accepted Answer

Vasodilation increases blood flow and oxygenation, enhancing hemoglobin coloration

Question 4

Which of the following best describes the acid mantle of the skin?

Accepted Answer

A slightly acidic film formed by sweat and sebum that inhibits bacterial growth

Question 5

Which process is initiated in the skin upon exposure to sunlight and is essential for bone health?

Accepted Answer

Conversion of 7-dehydrocholesterol to cholecalciferol (Vitamin D$_3$)

Question 6

Which of the following is NOT a function of the skin?

Accepted Answer

Production of red blood cells

Question 7

A patient with decreased oxygenation of the blood will most likely exhibit which skin color change?

Accepted Answer

Bluish tint due to reduced hemoglobin oxygenation (cyanosis)

Question 8

Which of the following skin changes is most commonly associated with aging?

Accepted Answer

Decreased melanocyte activity leading to paler skin

Question 9

Which skin structure is responsible for detecting vibration?

Accepted Answer

Lamellated (Pacinian) corpuscles

Question 10

Which of the following best explains why elderly individuals are more prone to overheating?

Accepted Answer

Decreased blood flow and sweat gland atrophy

Question 11

Which equation correctly represents the initial step in Vitamin D synthesis in the skin?

Accepted Answer

$7	ext{-dehydrocholesterol} ightarrow 	ext{cholecalciferol (Vit. D}_3)$

Question 12

Which of the following mechanisms helps the skin prevent water loss?

Accepted Answer

Keratin and glycolipids in the epidermis

Question 13

A patient with a genetic mutation resulting in fewer tight junctions between skin cells would most likely experience which of the following?

Accepted Answer

Greater water loss and increased risk of infection

Question 14

Which of the following is a correct description of insensible perspiration?

Accepted Answer

Continuous water loss through the skin, about 0.5 L/day, not perceived as sweat

Question 15

Which cells in the skin are most important for immune defense?

Accepted Answer

Dendritic cells and macrophages

Question 16

Which of the following changes in the skin is LEAST likely to occur with aging?

Accepted Answer

Increased subcutaneous fat

Question 17

A person with a diet high in carrots may develop an orange tint to their skin. Which layer is most likely to show this pigment accumulation?

Accepted Answer

Stratum corneum

Question 18

Which of the following best describes the role of the hypothalamus in skin function?

Accepted Answer

It regulates sweat gland secretion and blood flow to maintain body temperature

Question 19

Which tactile receptor is most sensitive to light touch?

Accepted Answer

Tactile (Meissner) corpuscles

Question 20

Which of the following is a multi-step process that explains how the skin helps maintain calcium homeostasis?

Accepted Answer

UV exposure converts 7-dehydrocholesterol to cholecalciferol, which is then modified by the liver and kidneys to calcitriol, promoting calcium absorption in the digestive tract

The Integumentary System: Functions and Aging

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