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Blood Vessels Anatomy & Physiology

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Terms in this set (21)

  • What are the three layers (tunics) of a blood vessel wall?
    Tunica intima (innermost, endothelium), tunica media (middle, smooth muscle and elastic tissue), and tunica externa (outermost, connective tissue).
  • What is the function of the tunica intima?
    It is the innermost layer composed of simple squamous epithelium (endothelium) that lines the lumen and provides a smooth surface for blood flow.
  • Which blood vessels have only the tunica intima layer?
    Capillaries consist solely of the tunica intima to allow efficient exchange of gases and nutrients.
  • What is the primary role of the tunica media?
    It contains circular smooth muscle responsible for vasoconstriction and vasodilation, regulating blood pressure and flow.
  • How does the tunica media differ between arteries and veins?
    The tunica media is thicker in arteries with more smooth muscle and elastic fibers, while veins have a thinner tunica media.
  • What is the function of the tunica externa?
    It provides structural support and elasticity with connective tissue and elastic fibers, protecting vessels from high pressure.
  • What are the three main types of arteries?
    Elastic arteries (large, pressure buffers), muscular arteries (medium, regulate blood flow), and arterioles (small, regulate flow into capillaries).
  • What is the role of elastic arteries?
    They act as pressure buffers, expanding during systole and recoiling during diastole to maintain blood pressure.
  • How do muscular arteries regulate blood flow?
    Through thick layers of smooth muscle in the tunica media, they perform vasoconstriction and vasodilation to control blood distribution.
  • What is the function of arterioles?
    Arterioles regulate blood flow into capillary beds and are primary regulators of systemic blood pressure.
  • What is an anastomosis in blood vessels?
    It is a connection between two or more arteries supplying the same area, providing alternate routes for blood flow.
  • What is the Circle of Willis?
    A hexagonal arterial anastomosis at the base of the brain ensuring constant blood flow through collateral circulation.
  • What is the structure and function of capillaries?
    Capillaries have walls of only endothelium allowing exchange of gases, nutrients, and wastes between blood and tissues.
  • Name the three types of capillaries based on permeability.
    Continuous (unbroken lining), fenestrated (pores for increased permeability), and sinusoids (large gaps for cells and molecules).
  • What regulates blood flow through capillary beds?
    Precapillary sphincters, rings of smooth muscle that open or close to control blood flow.
  • What are the main types of veins?
    Venules, small/medium veins, and large veins, all returning blood to the heart with valves to prevent backflow.
  • What is the function of valves in veins?
    Valves prevent backflow of blood, especially in veins of the lower extremities, aiding venous return.
  • What mechanisms assist venous return to the heart?
    The skeletal muscle pump, respiratory pump, and venous valves help overcome low pressure and gravity.
  • What is the hepatic portal system?
    A venous system that carries nutrient-rich blood from the intestines to the liver for processing before returning to the heart.
  • Describe pulmonary circulation.
    Blood flows from the right heart to the lungs for oxygenation and returns to the left heart.
  • Describe systemic circulation.
    Oxygenated blood is pumped from the left heart to the body tissues and deoxygenated blood returns to the right heart.