Which one of the following is synthesised in human body that dilates b

Which one of the following is synthesised in human body that dilates blood vessels and increases blood flow ?

Nitric oxide
Nitrous oxide
Nitrogen dioxide
Nitrogen pentoxide
This question was previously asked in
UPSC IAS – 2024
The question asks for a substance synthesized in the human body that dilates blood vessels and increases blood flow.
Nitric oxide (NO) is a molecule produced by cells in the endothelium (lining of blood vessels) and other tissues. It is a potent vasodilator, meaning it causes the smooth muscles in the walls of blood vessels to relax, leading to increased diameter and blood flow. This process is crucial for regulating blood pressure and blood flow to different parts of the body.
Nitrous oxide (N₂O), also known as laughing gas, is an anesthetic and analgesic gas used in medicine but is not synthesized in the human body for vasodilation.
Nitrogen dioxide (NO₂) and Nitrogen pentoxide (N₂O₅) are oxides of nitrogen that are primarily environmental pollutants and industrial chemicals, not molecules synthesized endogenously in the human body for physiological functions like vasodilation.
Therefore, Nitric oxide is the correct answer.
Nitric oxide (NO) acts as a signaling molecule in the cardiovascular system, promoting vasodilation by activating guanylate cyclase, which leads to the relaxation of vascular smooth muscle cells. This mechanism is important for regulating blood pressure and tissue perfusion.
NO plays various other roles in the body, including neurotransmission, immune response, and muscle function. The discovery of NO’s role as a signaling molecule in the cardiovascular system was awarded the Nobel Prize in Physiology or Medicine in 1998. Medications like nitroglycerin, used to treat angina (chest pain), work by releasing NO, which dilates coronary arteries. Sildenafil (Viagra) also works by enhancing the effects of NO on blood vessels.