Adrenaline helps in emergency situation by providing energy so that the major muscles of the body can respond to the perceived threat.
In danger, the brain then sends nerve impulses to the adrenal gland in the kidneys. When the nerve signal reaches the adrenal gland, chromaffin cells, in the medulla of the adrenal gland, release epinephrine or adrenaline. It then enters the bloodstream. It is thus carried around the body to cells in various locations, where it initiates several responses.
1. Adrenaline, along with another hormone called glucagon, is responsible for the breakdown of glycogen in liver cells. Glycogen is a form of energy storage. This gives energy to the muscles
2. Adrenaline effects the skin also. Restriction of the arteries is caused by the binding of epinephrine/adrenaline to some alpha-adrenergic receptors. This cuts off blood supply to the skin. This results in the contraction of the smooth muscle cells in the skin, which cause the raising of the hairs on the surface of the skin.
3. The lungs contain smooth muscle. Epinephrine causes smooth muscles to relax. Specifically, epinephrine binds to beta-2-adrenergic receptors on bronchiole muscle cells. This allows the bronchioles to relax, which enables intensified respiration.
4. Adrenaline binds to beta-adrenergic receptors on heart muscle cells. This causes the contraction rate of the heart to increase. This ultimately leads to increased blood supply to the tissues in the body.
