Adrenaline is a hormone, and is secreted from the adrenal glands-which are situated just above the kidneys.Whenever you are nervous or excited, your body will secrete this hormone; because your brain sends messages along nerves to the adrenal glands, which tells them to secrete adrenaline into the blood stream.The function of adrenaline is to prepare the body for something (whatever is making you nervous).henever you are nervous or excited, your body will secrete this hormone; because your brain sends messages along nerves to the adrenal glands, which tells them to secrete adrenaline into the blood stream. The function of adrenaline is to prepare the body for something (whatever is making you nervous).