What physical characteristic primarily affects peripheral resistance?

The primary physical characteristic that affects peripheral resistance is the diameter of arteries. Peripheral resistance refers to the resistance of the arteries to blood flow, which is influenced significantly by their size. When the diameter of the arteries decreases (such as during vasoconstriction), resistance increases, making it harder for blood to flow through. Conversely, when arteries dilate (vasodilation), resistance decreases, allowing blood to flow more freely.

This relationship is crucial for the regulation of blood pressure and overall cardiovascular health. Changes in artery diameter can be influenced by various factors such as neural signals, hormonal changes, and physical activity, which can impact how well blood can circulate throughout the body. Other factors listed, such as heart rate, blood volume, and body temperature, may play secondary roles in cardiovascular dynamics but do not directly impact peripheral resistance in the same fundamental way that vessel diameter does.