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Cardiovascular System II: Blood Vessels - Anatomy & Physiology

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Terms in this set (32)

  • Primary functions of blood vessels

    Transport blood to tissues for exchange of gases, nutrients, and wastes; regulate blood flow and pressure; secrete chemicals.

  • Three main types of blood vessels

    Arteries distribute blood away from the heart, capillaries enable exchange between blood and tissues, and veins collect blood and return it to the heart.

  • Tunica intima structure and function

    Innermost layer composed of endothelium continuous with heart lining; provides smooth surface to minimize friction; includes subendothelial connective tissue and internal elastic lamina.

  • Role of elastic fibers in blood vessels

    Provide distensibility (stretch under pressure) and elasticity (recoil to original size after stretching).

  • Tunica media composition and function

    Middle layer of smooth muscle cells and external elastic lamina; controls vessel diameter via vasoconstriction and vasodilation, regulated by sympathetic vasomotor nerves.

  • Tunica externa (adventitia) characteristics

    Outermost layer of dense irregular collagenous connective tissue; supports vessel and prevents overstretching; contains vasa vasorum supplying outer vessel layers.

  • Differences between arteries and veins

    Arteries have thicker tunica media and more elastic laminae due to higher pressure; veins have larger lumens, thinner walls, fewer elastic fibers, and often contain valves.

  • Classification of arteries by size and function

    Elastic arteries (largest, near heart), muscular arteries (medium, distribute blood to organs), and arterioles (smallest, regulate flow into capillaries).

  • Function of metarterioles and precapillary sphincters

    Metarterioles feed capillary beds; precapillary sphincters regulate blood flow into true capillaries by contracting or relaxing.

  • Vein characteristics and function

    Veins outnumber arteries, have larger lumens, thinner walls, and serve as blood reservoirs holding about 70% of blood volume; contain valves to prevent backflow.

  • Vascular anastomoses

    Connections between blood vessels providing collateral pathways; include arterial, venous, and arteriovenous anastomoses.

  • Definition of hemodynamics

    Study of blood flow physiology, driven by pressure gradients created by the heart, with flow inversely related to resistance.

  • Factors determining blood flow

    Blood flow is directly proportional to pressure gradient and inversely proportional to resistance.

  • Three main factors influencing blood pressure

    Peripheral resistance, cardiac output, and blood volume.

  • Peripheral resistance determinants

    Blood vessel radius (inverse relation), blood viscosity, and vessel length.

  • Cardiac output formula

    CO = stroke volume × heart rate.

  • Relationship between pressure, cardiac output, and resistance

    Pressure gradient (ΔP) = CO × PR (peripheral resistance).

  • Mean arterial pressure (MAP) calculation

    MAP ≈ diastolic pressure + 1/3 (systolic pressure – diastolic pressure).

  • Pulse pressure definition

    Difference between systolic and diastolic pressures, typically about 40 mm Hg.

  • Mechanisms aiding venous return

    Venous valves prevent backflow, skeletal muscle pumps squeeze veins, and respiratory pump uses pressure changes during breathing to propel blood.

  • Short-term nervous system control of blood pressure

    Sympathetic stimulation increases heart rate and vasoconstriction raising BP; parasympathetic stimulation decreases heart rate lowering BP.

  • Baroreceptor reflex function

    Negative feedback loop detecting blood pressure changes via stretch receptors to adjust sympathetic and parasympathetic output.

  • Endocrine hormones affecting blood pressure

    Epinephrine, norepinephrine, thyroid hormone increase CO; angiotensin-II causes vasoconstriction; ANP causes mild vasodilation.

  • Long-term blood pressure regulation

    Urinary and endocrine systems regulate blood volume via hormones (ADH, aldosterone, ANP, angiotensin-II) affecting water and sodium retention or excretion.

  • Capillary structure

    Walls consist of a single layer of endothelial cells and basal lamina; very thin (~0.2 μm) to allow exchange.

  • Three types of capillaries

    Continuous (least leaky), fenestrated (pores for rapid exchange), and sinusoidal (most leaky, large gaps).

  • Capillary exchange mechanisms

    Diffusion through gaps and membranes, osmosis, and transcytosis for larger molecules.

  • Myogenic mechanism of autoregulation

    Arterioles constrict when pressure rises to reduce flow and dilate when pressure falls to maintain constant tissue perfusion.

  • Metabolic controls of tissue perfusion

    Low oxygen and high CO2/hydrogen ions cause arteriolar dilation; high oxygen and low CO2 cause constriction.

  • Capillary hydrostatic and osmotic pressures

    Hydrostatic pressure pushes water out (~35 mm Hg arteriole end, 15 mm Hg venule end); osmotic pressure (~22 mm Hg) pulls water in due to plasma proteins.

  • Net filtration pressure (NFP) at capillary ends

    Arteriole end: NFP positive, water filtered out; venule end: NFP negative, water absorbed back into capillary.

  • Causes of edema

    Increased capillary hydrostatic pressure, decreased osmotic pressure, or lymphatic obstruction leading to excess interstitial fluid.