Adrenaline: Definition & Effects

Instructor: Sarah Phenix
In this lesson, we will explore the hormone adrenaline to learn what it is, where it is produced, and what it does to the organ systems of your body when it is released.

What is Adrenaline

If you've ever experience an 'adrenaline rush' than you'll understand what people mean when they refer to the 'high', or euphoria, that some people experience when they do something they deem risky, such as skydiving, bungee jumping, or parasailing. So what does that sense of euphoria come from? Well, it's all due to the biological chemical adrenaline, which is also known as epinephrine. Now, I'm sure you could easily think back to any of the many medical shows on TV and remember a time when a doctor urgently called for a syringe of epinephrine, right? Well, now you know that they were calling for an adrenaline shot, cool right?

Ok, so what does this actually mean? Well, adrenaline is one of the many biological hormones that our bodies produce (other such examples are testosterone and human growth hormone). In other words, hormones are a chemical produced by a gland within the body that is sent via the circulatory system to target specific organs and regulate their functioning. Alright, now that we know what a hormone is, let's take a moment to explore where the hormone adrenaline is produced.

Adrenal Gland

The adrenal gland - well, it's certainly no coincidence that adrenaline is named after the particular gland that produces it. The adrenal gland is a small triangular gland that sits atop each of your two kidneys, like a little hat. Now, with that said, the adrenal gland doesn't just synthesize (or create) adrenaline. Oh, no, no my friend - this very important endocrine gland (or hormone producing gland) is responsible for synthesizing many different hormones; however, each is produced within its own layer of the tissue. Thus, adrenaline is produced by a specific layer of tissue, called the medulla of the adrenal gland, which simply refers to the middle tissue of the gland.

Adrenal Gland Location
Adrenal Gland

The really cool thing about adrenaline is that it is the major player in your body's 'fight-or-flight' response to stressful situations. If you've never heard of 'fight-or-flight', it's the term used to refer to the preparation your body undergoes to either fight for survival or run for your life. It's a seriously important response that is regulated by your autonomic nervous system, or the automated control portion of your nervous system, which is really important because that means you don't have to think about it for it to work. Ok, so what does this 'fight-or-flight' response actually do to the systems of your body, you ask? Well let's take a look.

The Adrenaline Rush: Physiology

Ok, so let's consider a little scenario. Let's say you're walking down your local street and turn a corner to find a hoard of blood-thirsty kittens on a rampage - that's right, I said kittens.

Your brain is the first thing that registers the danger in front of you, and it initiates a cascade of neural chemicals resulting in the triggering of a part of your autonomic nervous system called the sympathetic nervous system, which essentially 'sympathizes' with your situation by activating your adrenal glands. As a result, a huge rush of adrenaline starts pumping through your veins causing major changes to specific organs of your body:

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