#vasoconstriction

• Angiotensin — A peptide hormone with potent vasoconstrictive action, derived from a plasma precursor (angiotensinogen) through an enzymatic cascade involving renin and angiotensin-converting enzyme (ACE). This well-defined structural element plays a fundamental role in regulating arterial blood pressure, stimulating aldosterone secretion by the adrenal glands, and maintaining fluid and electrolyte balance in the body, while also serving as the primary target for modern antihypertensive treatments.
• Arteriole — A microscopic blood vessel, with a diameter under 100 micrometers, structurally located between the terminal ends of large arteries and the capillary network. Due to the well-developed smooth muscle layer within their walls, arterioles act as the primary resistance vessels of the circulatory system, playing a fundamental role in regulating blood pressure and regional blood flow distribution through vasoconstriction and vasodilation.