When I put my finger on my neck, I can feel my heartbeat. I can count the beats. I can tell if it speeds up, and if it slows down. And lately, it's been doing a lot more speeding up than usual. I would guess that that indicates higher than normal levels of adrenaline in my blood.
Adrenaline acts on the sympathetic branch of the nervous system. It makes your heart beat faster and stronger; it makes your pupils dilate; it slows digestion; it constricts your blood vessels; and I think it probably also increases blood sugar levels. I get adrenaline rushes when I'm startled, when I'm angry - and when I'm with you. Hell, when I think about you I get an adrenaline rush. My heart beats faster, stronger; my pupils dilate; I go on a little bit of a sugar high.
I don't even have to be around you. But I'd much rather be around you than just think about you. Because when I'm around you, life just feels so much better. When I'm around you, it's kind of like being drunk. Which could be considered unsafe, since alcohol lowers inhibitions, so for you to be like my alcohol could potentially mean that there could be trouble. But I don't think so. I think we'll be fine.
But when I'm around you, and I put my finger on my neck, I can feel my heartbeat. And I can feel that my heart's about to burst, break, explode, and rupture from sheer joy - and also from adrenaline.