CogKnoSys

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Physical

Adrenaline Release

Adrenaline release is the body's quick chemical signal that gets you ready to face danger or stress.

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The idea

Adrenaline, also called epinephrine, is a hormone that helps the body react fast to danger or stress. It is made mainly by the adrenal glands. A small number of nerve cells in the medulla oblongata, at the base of the brain, also make it. Adrenaline plays a central part in the fight-or-flight response, the body's quick reaction to a threat.

Once adrenaline enters the blood, it reaches organs all over the body within moments. It makes the heart pump out more blood by acting on the SA node, the heart's natural pacemaker. It also sends more blood to the muscles, widens the pupils, and raises the amount of sugar in the blood for quick energy. Adrenaline causes these changes by binding to alpha and beta receptors, which are proteins on the surface of cells.

Adrenaline is not only a human chemical. It is found in many animals and even in some single-celled organisms. It has even been found in a plant called Scoparia dulcis. When the threat is over, adrenaline levels drop and the body slowly settles back to its resting state.

Check yourself

Question 1 of 3

Besides the adrenal glands, where in the body is adrenaline made?

Pick one. The first pick counts.

Composition

what it's made of

  • Adrenal glands — The main source of the adrenaline that enters the blood.
  • Brainstem neurons — A small group of nerve cells in the medulla oblongata that also make adrenaline.
  • Alpha and beta receptors — Proteins on cells that adrenaline binds to, which start its effects.
  • Bloodstream — Carries the hormone from where it is made to organs throughout the body.

Connection

how it relates

Under Sympathetic Nervous System

Cause and effect

  1. Fight or Flight Responsestrength 90 of 100

    Adrenaline release is one of the main ways the body carries out the fight-or-flight response.

  2. Cardiac Musclestrength 60 of 100

    Adrenaline raises the heart's output, so the heart muscle pumps harder and faster.

Related

  1. Fear and Anxietystrength 70 of 100

    Feeling afraid or threatened can trigger a rush of adrenaline.

Change

how and why it evolves

Past
The quick stress reaction that adrenaline drives began long before humans, which is why many animals share it.
Now
Today adrenaline is both a natural hormone and a common medication. Doctors give it in emergencies such as severe allergic reactions.
Next
Researchers are likely to keep studying how frequent stress, and the adrenaline surges it brings, may affect long-term health.

Knowledge you can walk. Read the idea, then step up, across or down.

Adrenaline Release

Adrenaline release is the body's quick chemical signal that gets you ready to face danger or stress.

Learn, discuss, create, buy or invest

The idea

Adrenaline, also called epinephrine, is a hormone that helps the body react fast to danger or stress. It is made mainly by the adrenal glands. A small number of nerve cells in the medulla oblongata, at the base of the brain, also make it. Adrenaline plays a central part in the fight-or-flight response, the body's quick reaction to a threat.

Once adrenaline enters the blood, it reaches organs all over the body within moments. It makes the heart pump out more blood by acting on the SA node, the heart's natural pacemaker. It also sends more blood to the muscles, widens the pupils, and raises the amount of sugar in the blood for quick energy. Adrenaline causes these changes by binding to alpha and beta receptors, which are proteins on the surface of cells.

Adrenaline is not only a human chemical. It is found in many animals and even in some single-celled organisms. It has even been found in a plant called Scoparia dulcis. When the threat is over, adrenaline levels drop and the body slowly settles back to its resting state.

Check yourself

3 quick questions, instant feedback.