Adrenaliini

Adrenaliini, commonly known as adrenaline or epinephrine, is a catecholamine hormone and neurotransmitter produced by the adrenal medulla and certain neurons in the central nervous system. It is a central component of the body's acute stress response, preparing the organism for fight-or-flight by rapidly modifying cardiovascular, metabolic, and respiratory function.

Synthesis and release: Adrenaliini is synthesized from norepinephrine in chromaffin cells of the adrenal medulla, via phenylethanolamine N-methyltransferase. It is released into the bloodstream in response to sympathetic activation, hypoglycemia, or exercise, and can also act as a neurotransmitter in the brain.

Mechanism of action: Adrenaliini exerts its effects by binding to adrenergic receptors—alpha-1, alpha-2, beta-1, and beta-2—distributed across vascular smooth muscle, the heart, and other tissues. Alpha-1 stimulation raises blood pressure through vasoconstriction; beta-1 increases heart rate and contractility; beta-2 promotes bronchodilation and increases glucose release in some tissues, contributing to increased energy availability.

Physiological and clinical relevance: In healthy physiology adrenaliini supports rapid energy mobilization, airway openness, and blood pressure regulation during stress. Clinically, it is used in the management of anaphylaxis, cardiac arrest, and for hemodynamic support during shock; it is also used as a vasoconstrictor in regional anesthesia and in some asthma treatments. Side effects include tachycardia, hypertension, anxiety, tremor, and potential arrhythmias.

History and naming: The hormone is referred to as adrenaline in many countries and epinephrine in the United States. It was identified and isolated in the early 20th century, with medical applications expanding in the following decades.