Emergency Medical Technician (EMT) Intermediate Practice Exam

What physiological response occurs in blood vessels when exposed to cold temperatures?

1. Vasodilation and increased blood flow

2. Constriction and diversion of blood away from the skin

3. Hyperemia in the skin

4. Expanded blood vessel capacity

The correct answer is: Constriction and diversion of blood away from the skin

When blood vessels are exposed to cold temperatures, the physiological response typically involves constriction, which is a process known as vasoconstriction. This response occurs as a mechanism to conserve body heat. By narrowing the blood vessels, the body helps to redirect blood flow away from the extremities and towards the core, where vital organs are located. This action preserves overall body temperature, protecting the body from the potentially harmful effects of cold exposure. Vasoconstriction limits blood flow to the skin and peripheral areas, which can result in cooler skin temperatures and a decreased risk of heat loss. This is especially crucial in extremely cold environments where maintaining core body temperature is essential for survival. In contrast, other options describe responses not typical to cold exposure. For instance, vasodilation and increased blood flow would typically occur in response to warm temperatures, while hyperemia refers to increased blood flow often due to increased metabolic activity or warmth. Lastly, the concept of expanded blood vessel capacity does not align with the body's response to cold, where rather the goal is to reduce capacity through constriction.