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Blood Vessels and Hemodynamics - Anatomy & Physiology

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  • What are the three main layers of blood vessel walls?

    Tunica intima (endothelium & basement membrane), tunica media (smooth muscle), and tunica adventitia (collagen & elastic fibers with blood and nerve supply).

  • How do elastic arteries differ from muscular arteries?

    Elastic arteries have more elastic fibers in the tunica media for recoil and pressure maintenance; muscular arteries have thicker smooth muscle for vasoconstriction and vasodilation.

  • What is the function of arterioles in blood flow regulation?

    Arterioles control blood flow into capillaries via vasoconstriction or vasodilation and regulate systemic blood pressure.

  • Describe the structure and function of veins compared to arteries.

    Veins have thinner tunica intima and media, thicker tunica adventitia, larger lumen, and valves to prevent backflow; they return blood to the heart at lower pressure.

  • What causes varicose veins?

    Weakened or damaged valves in veins cause blood to pool and veins to become enlarged and twisted, leading to varicose veins.

  • What is vascular anastomosis and its significance?

    Connections between blood vessels (collateral vessels) that provide alternative pathways for blood flow, important in heart, brain, and joints.

  • Define blood pressure (BP) and how it is measured.

    BP is the force exerted by blood on vessel walls, measured in mm Hg using a sphygmomanometer and stethoscope detecting Korotkoff sounds.

  • What is mean arterial pressure (MAP) and how is it calculated?

    MAP is the average arterial pressure during one cardiac cycle, calculated as \(\text{diastolic} + 0.33 \times (\text{systolic} - \text{diastolic})\).

  • List three factors that can increase mean arterial pressure (MAP).

    Increased cardiac output, increased total blood volume, and increased systemic vascular resistance.

  • What determines systemic vascular resistance?

    Resistance depends on vessel diameter, blood viscosity, vessel length, and presence of obstructions.

  • How does blood velocity change across different vessel types?

    Velocity decreases as cross-sectional area increases in capillaries, allowing time for exchange, then increases again in veins.

  • What is the role of baroreceptors in blood pressure regulation?

    Baroreceptors in carotid sinus and aorta detect BP changes and trigger reflexes to maintain stable blood pressure.

  • Explain the sympathetic nervous system's effect on blood pressure.

    Sympathetic activation increases heart rate, contractility, and vasoconstriction, raising blood pressure.

  • What is the function of capillaries in the circulatory system?

    Capillaries facilitate exchange of gases, nutrients, and wastes between blood and tissues.

  • Name the three types of capillaries and their permeability characteristics.

    Continuous (least leaky), fenestrated (moderately leaky), and sinusoidal (most leaky).

  • Describe the mechanisms of capillary exchange.

    Diffusion, transcytosis, and bulk flow driven by hydrostatic and osmotic pressures.

  • What is the significance of pre-capillary sphincters?

    They regulate blood flow into capillary beds by opening or closing in response to tissue needs.

  • How does peripheral resistance affect blood pressure?

    Increased peripheral resistance raises blood pressure by opposing blood flow; decreased resistance lowers it.

  • What is the role of valves in veins?

    Valves prevent backflow of blood, ensuring unidirectional flow toward the heart.

  • What percentage of blood is typically found in systemic veins at rest?

    Over 60% of blood is found in veins at rest, acting as a blood reservoir.