Summary
A hormone from the adrenal glands that prepares the body for fight or flight.
In depth
Released from the adrenal medulla in stress; increases heart rate, widens airways and pupils, mobilises glucose and diverts blood to muscles. It acts via beta-adrenergic receptors and cAMP.
Adrenaline acts within seconds on many tissues. Its effects last minutes. It is made from tyrosine.
Example: adrenaline is used in emergency treatment of cardiac arrest and anaphylaxis.
Adrenaline (epinephrine) is released by the adrenal medulla within seconds in response to stress, under control of sympathetic nerves, triggering the fight-or-flight response. It binds to adrenergic receptors, raising heart rate and blood pressure, dilating bronchioles and pupils, diverting blood to skeletal muscle and away from digestion and skin, and mobilising glucose and fatty acids.
It acts through second messengers (cAMP), amplifying the signal in a cascade. Effects fade quickly as it is broken down or reabsorbed. It is also a neurotransmitter and medicine for anaphylaxis and cardiac arrest (EpiPen).
Example: the pounding heart and pale skin when frightened.
Frequently asked questions
What is Adrenaline?
A hormone from the adrenal glands that prepares the body for fight or flight.
Which area of biology covers Adrenaline, and how advanced is it?
Adrenaline is one of the 54 topics in Reproduction & Endocrinology. It is rated Beginner, so it suits learners who are starting out in biology. Related topics in this area include Steroid and Peptide Hormone Mechanisms, Hormones, Hypothalamic-Pituitary Axis.
Why does Adrenaline matter?
A rapid hormone, bridging nervous and endocrine systems.
Can you give an example of Adrenaline?
EpiPens deliver adrenaline for anaphylaxis.
What should I learn before Adrenaline?
Adrenaline is a Beginner topic, so no earlier topic is required. Other Beginner topics in Reproduction & Endocrinology that pair well with it include Reproduction, Asexual Reproduction, Sexual Reproduction.
What topics are related to Adrenaline?
The closest topics to Adrenaline are Steroid and Peptide Hormone Mechanisms, Hormones, Hypothalamic-Pituitary Axis, Endocrine Tumours. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Adrenaline?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Adrenaline. To practise the whole of Reproduction & Endocrinology, use the Reproduction & Endocrinology quiz.
How is Adrenaline different from Steroid and Peptide Hormone Mechanisms?
Adrenaline: A hormone from the adrenal glands that prepares the body for fight or flight. Steroid and Peptide Hormone Mechanisms: Steroid hormones cross membranes and alter transcription; peptide hormones bind surface receptors and activate second messengers. Read both side by side and note what each one explains.
How should I study Adrenaline step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Steroid and Peptide Hormone Mechanisms and explain the difference aloud. Finally, take the Reproduction & Endocrinology quiz and come back to this page for any question you miss.