The prostaglandins are molecules which play a regulatory role in the body. Theseare synthesised from the essential fatty acids. These regulatory molecules are relatively large and contain twenty carbon atoms. The prostaglandins exhibit a wide variety of activities.
Blood pressure homeostasis
The human body has wonderful regulatory mechanisms ensuring survival. Thus when the body temperature falls, there is a mechanism for elevating the body temperature. This kind of mechanism is available for the maintenance of the blood pressure also. This kind of regulatory process is called homeostasis. There are two kinds of mechanisms involved. There are molecules which can elevate the blood pressure. This is achieved through the constriction of the blood vessels. Serotonin is the best example for such a substance. Likewise, there are molecules which can bring about a drop in the blood pressure and this is achieved through the dilation of the blood vessels. More than one prostaglandin is capable of achieving this reduction in the blood pressure.
The food which we have consumed passes through the gastrointestinal tract without any effort on our part. All that we have to do is to swallow the food. The body will take care of the rest. This is mainly achieved through the relaxation of the smooth muscles lining the gastrointestinal tract. The prostaglandins promote this relaxation.
Contraction of the uterus
The contraction of the uterus plays an important part in the delivery of a baby at the end of the pregnancy. This process is called theparturition. Contraction of the uterus is promoted by the prostaglandins in conjunction with the pituitary hormone oxytocin.
Secretion of acid in the gastric region is important in the digestive process. The enzyme pepsin which acts in the gastric region and is responsible for digesting the proteins, has evolved in such a fashion that it can function only in an acidic environment. Histamine is a substance which is capable of promoting acid secretion. The prostaglandins, on the other hand, inhibit the secretion of acid. Thus, any drug which acts by inhibiting the synthesis of the prostaglandins, can cause irritation of the stomach because of increased acid secretion.
Bronchioles are air passages which promote the entry of oxygen into the lungs. Constriction of the airways leads to breathlessness and suffocation. This is exactly what is happening in asthma where the bronchioles constrict as a result of the exposure to allergens. The prostaglandins are able to dilate the bronchioles and thereby, promoting the free passage of oxygen.
Involvement in fever
The presence of fever is indicated by increased body temperature. People try to get rid of fever by taking substances such as paracetamol. In fact, fever provides a warning that infection has set in. It is also a defensive mechanism. The body temperature is elevated to prevent the growth of the infecting agent. The prostaglandins can increase the body temperature by acting at the thermo regulatory centre in the brain.
Thus, it is clear that the prostaglandins are efficient regulatory molecules. They monitor, regulate and implement.