craw Graw Hill Hill 0 of 43 Concepts completed (i) Multiple Cholce Question What layer of the blood vessel wall is composed of circularly arranged layers of smooth muscle cells? tunica intima tunica media tunica externa

The layer you're looking for is the tunica media! This middle layer is where the magic happens, as it allows blood vessels to regulate their diameter. Think of it as the muscle of the blood vessel that can either contract to narrow the vessel or relax to widen it, helping control blood flow and pressure throughout the body. In a real-world application, understanding the structure of the tunica media is crucial for medical professionals, especially when it comes to conditions like atherosclerosis or hypertension. Healthy smooth muscle in the tunica media maintains proper blood flow, while damage to this layer can lead to serious cardiovascular issues. Keep those vessels healthy!