Caffeine's wakefulness effect by blocking receptors for which chemical?

Caffeine's wakefulness effect by blocking receptors for which chemical?

• A. Dopamine
• B. Melatonin
• C. Adenosine
• D. Cortisol

Answer: (C)

Caffeine promotes wakefulness by blocking adenosine receptors in the brain. Adenosine builds up as you stay awake and binds to A1 and A2A receptors, which slows neural activity and promotes sleepiness. Caffeine acts as a competitive antagonist at these receptors, preventing adenosine from binding. With adenosine signaling reduced, neurons stay more active, leading to increased alertness. This effect can also indirectly boost other arousal-related neurotransmitters like dopamine and norepinephrine. The other substances listed aren’t the direct targets of caffeine’s wakefulness action, so they don’t explain caffeine’s primary mechanism.

Caffeine promotes wakefulness by blocking adenosine receptors in the brain. Adenosine builds up as you stay awake and binds to A1 and A2A receptors, which slows neural activity and promotes sleepiness. Caffeine acts as a competitive antagonist at these receptors, preventing adenosine from binding. With adenosine signaling reduced, neurons stay more active, leading to increased alertness. This effect can also indirectly boost other arousal-related neurotransmitters like dopamine and norepinephrine. The other substances listed aren’t the direct targets of caffeine’s wakefulness action, so they don’t explain caffeine’s primary mechanism.