Norepinephrine and epinephrine are also known as noradrenaline and adrenaline in other parts of the world. The terms refer to two vital hormones in the body which will facilitate the body reaction in certain situation. In most instances, the structure and function of these two hormones can be largely compatible although the level of stimulation that it gives as well as the regions and the sites on which it exerts the effect would be rather different. Therefore, in general the epinephrine is known as the ‘fight or flight hormone’ and the norepinephrine is known for its comparatively calming effect.
In the formation of these two chemical ingredients, the epinephrine is known to be formed in the adrenal glands, more specifically in the adrenal medulla. Although there is a certain amount of epinephrine also formed in the region, the bulk of its formation takes place in the post synaptic nerve endings in relation to stressful events. It also should be mentioned that, epinephrine is a derivative of norepinephrine where as the latter will be derived from dopamine precursors.
Epinephrine will increase the catabolism of glycogen to glucose in the liver cells in order to maintain supply in response to stressful events. It will also act on the receptors present in the heart and will increase its rate of contraction as well as its force of contraction. Its effect on the peripheral blood vessels will constrict them and thus the blood is shunted towards the core organs in the body. As you can see, all these events will lead to a body’s response to stressful events and will make the systems function at its peak.
Norepinephrine will exert a similar action although its release of glucose is largely dependent on the conversion of glycogen to glucose or else through conversion of fat deposits into fatty acids. It will increase the air flow to lungs by means of dilating the air passages in the lungs as well.
The norepinephrines action on nerves will make it effective over the brain functions whereas epinephrine does not exert such a significant action. Therefore, the norepinephrines are also known as psychoactive when used as a drug or else at times of its increase release.
Lastly, the epinephrine acts on both alpha receptors as well as on beta receptors to the same extent whereas the norepinephrine will act mostly on the alpha receptors. The changes in its action towards these receptors will make epinephrine effective in resuscitating a person in cardio respiratory arrest or else in order to prevent an immune reaction prior to giving an immune active substance or a drug.