What would be the most likely effect on the human body if the interaction between caffeine and adenosine receptor were covalent?

Caffeine acts as an adenosine-receptor antagonist. This means that it binds to these same receptors, but without reducing neural activity. Fewer receptors are thus available to the natural “braking” action of adenosine, and neural activity therefore speeds up (see animation).

he is very short, and he can only reach halfway up on the elevator buttons. but on a rainy day, he has his umbrella with him, and he uses it to poke the button at the top.