Pathophysiology

Pathophysiology Study Guide

©2018 of 131 3.5 Hypertension Hypertension, or high blood pressure, occurs when the force of the blood increases and hits the walls of the arteries to such an extent that it causes heart problems, like a heart attack. It is characterized by the quantum of blood pumped by the heart and the amount of resistance to the flow of blood in the arteries. In other words, if the heart pumps more blood and the arteries are narrow, the pressure of the blood is likely to be higher. Hypertension develops over many years and is likely to cause a stroke and heart attack. Many people show no symptoms of hypertension while few may experience headaches, shortness of breath, and bleeding from nose. Renin-Angiotensin-Aldosterone System The renin-angiotensin-aldosterone system (RAAS) is essential in regulating the volume of blood and systemic vascular resistance, which are essential in monitoring hypertension or high blood pressure. RAAS has the ability to influence cardiac output and pressure in the arteries. There are three components of the system: renin, angiotensin, and aldosterone. Renin is a proteolytic enzyme released from the kidney, which leads to the formation of the circulating substrate known as angiotensin in blood and tissues of the body. This released angiotensin stimulates the release of aldosterone from the adrenal cortex. When the body senses this fall in blood pressure, renin is released by the kidney in the bloodstream. Renin floats in the blood and converts the inactive angiotensin in the liver to the active form known as angiotensin I. Angiotensin I influences the blood pressure to some extent, but does not cause major changes. Most angiotensin I convert to angiotensin II, which is a powerful hormone and affects large changes in blood pressure. This is done by the molecule known as angiotensin converting enzyme (ACE) in the lungs. Apart from increasing the blood pressure, angiotensin II stimulates the release of aldosterone. Aldosterone acts as a powerful vasoconstrictor and leads to a significant increase in blood pressure. This also causes retention of salt and water in the kidney, again leading to hypertension. This mechanism is highly beneficial in understanding the changes in the blood pressure and finding the treatment for the same. Risk Factors There are numerous risk factors for high blood pressure or hypertension. The first one is age. In men, it is likely to occur after age 45, while women are prone to develop hypertension at an older age, like 60 plus. Moreover, it is hereditary, so people with a family history of hypertension are more likely to suffer. Another risk factor is being over-weight or suffering from obesity. As the weight increases, the requirement of oxygen and nutrient rich blood increases. High volume places high pressure on the walls of the arteries and causes hypertension. Another factor is lack of activity as it causes higher heart rates, making the heart work harder with each contraction. This leads to exertion of more force to the artery walls. Alcohol, smoking, and tobacco chewing temporarily increase blood pressure. Moreover, it damages the lining of the walls of the artery making them narrow, increasing blood pressure. Another factor is the intake of excessive salt or sodium in the diet. Sodium increases fluid intake by the body, which leads to high pressure in the blood. Similarly, inadequate potassium leads to an imbalance of sodium in the body cells and the body will retain more sodium. Another factor is Achieve Page 56