The adrenal glands sit atop your kidneys and work with the hypothalamus and pituitary glands to regulate metabolism and immunity. Most famously, the adrenal glands squish out the hormone adrenaline, which controls the body’s “fight or flight” response by speeding up your heart rate and otherwise pumping you up. Relax — don’t do it. Click on through to the I Heart Guts store to check out our adrenal gland gifts and stuff.