Final answer:
Caffeine consumption leads to pleasure and alertness because it blocks the action of the adenosine neurotransmitter and affects neurotransmitter levels, leading to increased brain activity.
Step-by-step explanation:
The immediate symptoms of caffeine consumption, such as pleasure, occur because caffeine quickly affects neurotransmitter levels in the brain. Caffeine is a central nervous system stimulant that is chemically similar to adenosine, a neurotransmitter in our brain. Caffeine works by blocking the action of adenosine on its receptors, preventing drowsiness and causing increased alertness. It also changes the levels of signaling molecules in the brain, leading to boosted energy metabolism. This interaction stimulates the brain, leading to the feeling of pleasure and increased alertness, and can also delay fatigue and sleep.