Which of the following statements about reflexes is true?

• A. Reflexes are automatic responses that do not require conscious thought.
• B. Reflexes always require input from the endocrine system.
• C. Reflexes only occur in response to pain stimuli.
• D. All reflexes involve the brain as the integration center.

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the concept of reflexes. Reflexes are automatic, involuntary responses to stimuli that help maintain homeostasis and protect the body from harm. They do not require conscious thought, meaning they occur without voluntary control.
2. Step 2: Analyze the first statement: 'Reflexes are automatic responses that do not require conscious thought.' This aligns with the definition of reflexes, as they are involuntary and automatic. Keep this statement in mind as a potential correct answer.
3. Step 3: Evaluate the second statement: 'Reflexes always require input from the endocrine system.' Reflexes are primarily mediated by the nervous system, not the endocrine system. The endocrine system regulates hormones and slower processes, so this statement is incorrect.
4. Step 4: Examine the third statement: 'Reflexes only occur in response to pain stimuli.' Reflexes can occur in response to various stimuli, such as light, sound, or touch, not just pain. For example, the pupillary light reflex responds to light, not pain. This statement is incorrect.
5. Step 5: Assess the fourth statement: 'All reflexes involve the brain as the integration center.' Some reflexes, such as spinal reflexes, are integrated in the spinal cord and do not involve the brain directly. Therefore, this statement is incorrect. Based on the analysis, the first statement is the correct answer.