MICROANATOMY

Detailed explanation-1: -Angiotensin-converting enzyme, found in the capillaries of the lungs, converts angiotensin I to angiotensin II. Angiotensin II causes vasoconstriction of the arterioles. This increases peripheral resistance and an increase in systemic arterial blood pressure.

Detailed explanation-2: -Peripheral vascular resistance (systemic vascular resistance, SVR) is the resistance in the circulatory system that is used to create blood pressure, the flow of blood and is also a component of cardiac function. When blood vessels constrict (vasoconstriction) this leads to an increase in SVR.

Detailed explanation-3: -Vasoconstriction is the narrowing of blood vessels, typically when the muscles of blood vessel walls become constricted, causing the vessel lumen to become smaller. Vasoconstriction can be a reaction to cold, stress, cigarette smoking, medications, or underlying medical conditions, such as the Raynaud phenomenon.

Detailed explanation-4: -The constriction of arterioles increases resistance, which causes a decrease in blood flow to downstream capillaries and a larger decrease in blood pressure. Dilation of arterioles causes a decrease in resistance, increasing blood flow to downstream capillaries and a smaller decrease in blood pressure.

Detailed explanation-5: -Four major factors interact to affect blood pressure: cardiac output, blood volume, peripheral resistance, and viscosity. When these factors increase, blood pressure also increases. Arterial blood pressure is maintained within normal ranges by changes in cardiac output and peripheral resistance.