Angiotensin is a peptide hormone that plays a crucial role in regulating blood pressure and fluid balance in the body. It is produced in response to low blood pressure or low sodium levels and acts primarily by constricting blood vessels, which increases blood pressure. The renin-angiotensin system (RAS) is the process through which angiotensin is formed and activated. It begins with the release of renin from the kidneys, which converts a protein called angiotensinogen into angiotensin I. This is then converted into angiotensin II, the active form that exerts its effects on blood vessels and the adrenal glands.