OCR General Certificate of Secondary Education (GCSE) Biology Practice Exam

What type of signal do sweat glands respond to for cooling purposes?

1. Sound signals

2. Nerve impulses

3. Blood pressure changes

4. Hormonal signals

The correct answer is: Nerve impulses

Sweat glands primarily respond to nerve impulses for cooling purposes. When the body temperature rises, the hypothalamus in the brain detects this change and activates the autonomic nervous system. In response, the sympathetic nerve fibers stimulate the sweat glands to produce sweat. As the sweat evaporates from the skin's surface, it cools the body. This process is a crucial part of thermoregulation, allowing the body to maintain a stable internal temperature despite environmental fluctuations. Other options such as sound signals, blood pressure changes, and hormonal signals do not directly initiate the sweating response. Sound signals do not influence the body's temperature regulation, while changes in blood pressure are more related to the cardiovascular system's responses rather than sweat gland activation. Hormonal signals, while involved in various physiological processes, are not the primary triggers for sweat production in response to temperature increases. Instead, it is the immediate response to nerve impulses that efficiently regulates body temperature through sweating.