What is the role of endorphins during continuous exercise?

• A. They stimulate the release of adrenaline from the adrenal glands.
• B. They directly cause muscle contraction by binding to actin.
• C. They act as neurotransmitters that reduce the perception of pain.
• D. They increase the rate of glucose uptake by muscle cells.

Answer: (C)

Verified step by step guidance

1. Understand the role of endorphins: Endorphins are neurotransmitters produced by the brain and nervous system. Their primary function is to reduce the perception of pain and promote a sense of well-being, especially during activities like continuous exercise.
2. Eliminate incorrect options: Analyze each option provided in the question. For example, endorphins do not stimulate adrenaline release from adrenal glands, nor do they directly cause muscle contraction by binding to actin. These functions are unrelated to endorphins.
3. Focus on the correct mechanism: Endorphins act as neurotransmitters that bind to opioid receptors in the brain. This interaction reduces the transmission of pain signals and enhances feelings of pleasure or euphoria, often referred to as the 'runner's high' during exercise.
4. Clarify the incorrect glucose uptake option: Endorphins do not directly increase the rate of glucose uptake by muscle cells. Glucose uptake is regulated by insulin and other metabolic pathways, not by endorphins.
5. Conclude with the correct answer: Based on the biological role of endorphins, the correct answer is that they act as neurotransmitters that reduce the perception of pain during continuous exercise.