Adrenaline, also known as epinephrine, is a hormone produced by the adrenal medulla that acts in the body in stressful situations.
Its secretion occurs quickly, and a complete action can be observed in a few minutes. Epinephrine has great application in medicine , being used, for example, in cases of cardiac resuscitation, anaphylaxis and bronchial asthma.
Summary about adrenaline
- Adrenaline, also known as epinephrine, is a hormone synthesized by the adrenal medulla.
- It promotes, among other actions, increased heart rate, glycogen degradation and fat degradation.
- It is released in stressful situations.
- It has application in medicine, being used in cases of cardiac arrest, anaphylaxis and bronchial asthma.
What is adrenaline?
Adrenaline is a hormone produced by the adrenal medulla . Also known as epinephrine, adrenaline is a hormone derived from the amino acid tyrosine and is released when the sympathetic nervous system is stimulated. Because it is released in stressful situations, it is considered a “fight or flight” hormone .
This hormone stands out for producing different effects, depending on the target cell affected. In some of them, the same receptor for the hormone is observed, however, the cells have different signal transduction routes or effector proteins. In others, the receptors for the hormone are different and generate different responses.
The adrenal glands are structures located at the upper poles of the kidneys , also known as the adrenals . The adrenals weigh about four grams and have two distinct parts: adrenal medulla and adrenal cortex.
The adrenal medulla is responsible for the secretion of the hormones adrenaline and noradrenaline , also known, respectively, as epinephrine and norepinephrine. The adrenal cortex is also responsible for producing hormones collectively called corticosteroids.
Adrenaline acts on different target tissues such as heart , skeletal muscle, adipose tissue and liver cells.
In the heart, adrenaline is related to increased heart rate and strength of contraction. In skeletal muscle, adrenaline is related to the breakdown of glycogen . In adipose tissue, adrenaline promotes the breakdown of fat.
Other actions of adrenaline include constricting some blood vessels and increasing metabolic activities. It is also worth noting that adrenaline acts on hepatic glycogen metabolism, however, this control is secondary in relation to the action of glucagon.
Adrenaline is released by the adrenal gland in situations of stress or excitement . It travels through the bloodstream and binds to receptors present on different cell types. As stated before, several different actions occur depending on the target tissue, however, in situations of stress or excitement, adrenaline, in general, acts to promote a rapid action of the organism in relation to the stimulus to which it was exposed.
By promoting the breakdown of glycogen in skeletal muscle in a stressful situation, for example, adrenaline increases the amount of glucose available, which is used as fuel to accelerate muscle activity. The same occurs in fat cells, with the breakdown of triacylglycerols to fatty acids, which are also a form of fuel for the cell . Adrenaline further increases blood flow to major skeletal muscles and reduces blood flow to the digestive system .
The speed with which adrenaline acts on our body in stressful situations is impressive. To get an idea of this speed, just think about how, in the face of a situation of danger or strong emotion, our heart rapidly accelerates its beats in a few seconds. This speed is important to ensure a quick and effective response by the body.
Adrenaline as a medicine
Due to its different effects on the body, adrenaline is used in different situations as a medicine. It is used, for example, in the treatment of anaphylaxis , a serious reaction triggered by hypersensitivity mechanisms and which is potentially fatal, requiring immediate action when it occurs. Other important uses of adrenaline concern cases of cardiac arrest and the management of severe episodes of bronchial asthma .