ETS Psychology Practice Test 2026 – All-in-One Study Guide for Exam Success!

Endorphins are neuropeptides that play a crucial role in the body, particularly in the modulation of pain. When endorphins are released, they bind to receptors in the brain to inhibit the perception of pain, acting as the body’s natural painkillers. This process can take place in response to stress or injury, leading to a reduction in discomfort and a sense of euphoria often referred to as the "runner's high.” This function is critical for allowing individuals to endure pain during activities such as exercise or overcoming injuries, thus promoting survivability in challenging situations.

The other options, while they refer to physiological processes, do not reflect the primary functions of endorphins. For instance, endorphins do not play a direct role in increasing hunger, regulating heart rate, or enhancing lung function. Each of those processes is governed by different hormones or neural mechanisms. Thus, the correct answer highlights the unique and important role that endorphins have in pain modulation within the body.