What is the effect of nitroglycerin on blood flow?

Nitroglycerin is a vasodilator, meaning it relaxes and widens blood vessels. This action primarily increases blood flow to the heart muscle by decreasing myocardial oxygen demand while simultaneously enhancing perfusion to heart tissues. The dilation of coronary arteries allows for more oxygen-rich blood to reach the heart, which is particularly beneficial during episodes of angina or in cases of acute myocardial infarction.

The other options address effects that are not the primary actions of nitroglycerin. While nitroglycerin can influence blood flow in other areas, its fundamental role is to improve oxygen delivery to the heart, which is crucial in emergency medical situations involving cardiac distress.