[SciShow intro plays]

[text: QQS: Where does love come from?]

Michael: It’s February, which means -- at least here in the the U.S -- your eyeballs are getting accosted by a barrage of red and pink heart-shaped lovey-dovey stuff. Now, I don’t want to rain on anyone’s Valentine’s Day, but this is bogus for a few reasons.

One, our hearts look nothing like those symbols, and two, our hearts have very little to do with how we actually feel love. So if you want to make a more accurate valentine, I suggest you cut that construction paper into the shape of a brain... or more specifically, the limbic system... or even more specifically, the hypothalamus.

See, the limbic system is the emotional center of your brain. It guides your emotional, motivational, and reward processes, and basically makes you feel all the feels, from pleasure to fear to anger. It also influences some of your biological rhythms, like sex drive. Nerve receptors all over your body send sensory stimuli -- say, the sound of a loved one’s voice, or the feeling of a hug -- to the limbic system, where it eventually gets forwarded to the hypothalamus.

Perched on top of your brain stem, this small but mighty bit of brain is your body’s visceral ground control, overseeing your entire autonomic nervous system -- meaning it’s in charge of processes you don’t consciously control, like blood pressure, digestion, and heart rate, for example.

It’s basically the boss of all the bosses -- the CEO of your body. When it comes to love and other feels, the hypothalamus uses those autonomic pathways to cause physical responses to match your emotions -- like how the sight of a secret love can leave you sweat-soaked, with a heart that feels like it’s going to jump out of your chest. In the same way, someone who’s heartbroken may experience their emotional stress in a very visceral way -- for example, through heartburn, high blood pressure, or changes in sleep and appetite.

Guided by your hypothalamus, your autonomic nervous system also influences the skeletal muscle system that lets you pull off facial expressions and posturing. So when it comes to communicating emotions, from “back off” to “come hither,” that’s your hypothalamus talking. And, it influences your endocrine system, which uses hormones to make your body do and feel all sorts of things, including, probably, love.

For one thing, it controls your pituitary, the master gland that then manages most of the other endocrine glands in your body -- as well as the hormones they release. That covers everything from your stress and excitement response to your libido. The hypothalamus also makes a few special hormones of its own -- like oxytocin, the famous “cuddle hormone,” which is involved in social bonding, among other things.

So in the end, if you want to get real about love, toss out the heart and start saying “I Hypothalamus You.” And what better way to do it than with a special SciShow Valentine’s Day card that actually says “I hypothalamus you?” Check ‘em out at dftba.com/scishow, and don’t forget to go to youtube.com/scishow and subscribe!