What controls blood flow into the capillary network?Multiple choice question.tunica mediaprecapillary sphincterslumen resistanceplaque formation

1. Break Down the Problem

We need to determine which option best explains how blood flow into the capillary network is controlled.

2. Relevant Concepts

• Tunica Media: This is the middle layer of blood vessels, which controls the diameter of the vessel and hence affects blood flow.
• Precapillary Sphincters: These are small muscles located at the junction of arterioles and capillaries that regulate blood flow into capillaries by constricting or relaxing.
• Lumen Resistance: This refers to the resistance to blood flow within the lumen of the blood vessels but does not directly control flow into capillaries.
• Plaque Formation: This pertains to the build-up of fatty deposits in arteries and can affect overall blood flow but is not a direct control mechanism for capillary flow.

3. Analysis and Detail

• Tunica Media: While important for regulating the overall blood vessel tone, it does not specifically control flow into capillaries.
• Precapillary Sphincters: These are essential for regulating blood flow specifically into capillaries, constricting or relaxing to either allow or restrict blood flow based on tissue demand.
• Lumen Resistance: Affects the overall flow rate but isn't a specific control mechanism.
• Plaque Formation: Affects blood vessels' health but is not a direct mechanism.

4. Verify and Summarize

Upon reviewing the options, precapillary sphincters are specifically designed to control blood flow into the capillary network. They act as gatekeepers, allowing blood to flow into the capillaries based on local tissue requirements.

Final Answer

Precapillary sphincters are what control blood flow into the capillary network.