APPLIED RADIOLOGICAL ANATOMY

Detailed explanation-1: -Precapillary sphincters are segments of smooth muscle that help direct bloodflow into capillaries. Because there is a limited amount of blood in the body, these sphinters are important in directing blood to the tissues that need it the most, and reducing the flow to inactive tissues.

Detailed explanation-2: -Precapillary sphincters represent important anatomical sites of blood flow regulation due to their strategic placement at branch points of proximal PAs, where they reduce both pressure and RBC flux into the downstream capillary bed and thereby regulate perfusion along the PA (Fig. 7).

Detailed explanation-3: -Capillaries are small blood vessels. Unlike arteries, they have very thin walls. Unlike veins, they do not have valves.

Detailed explanation-4: -Question: Precapillary sphincters regulate blood flow through a systemic capillary bed in response to low blood O2 levels Low O2 levels in the interstitial fluid (IF) • High blood pressure Low blood pH.