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Blood Vessels and Blood Pressure - Anatomy & Physiology

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Terms in this set (29)

  • Functions of blood vessels
    Transport blood to tissues for exchange of gases, nutrients, and wastes; regulate blood flow and pressure; secrete chemicals.
  • Three types of blood vessels
    Arteries distribute blood from heart; capillaries exchange substances with tissues; veins collect blood and return it to heart.
  • Tunics of blood vessel walls
    From inside out: tunica intima (endothelium), tunica media (smooth muscle and elastic fibers), tunica externa (connective tissue).
  • Role of tunica media
    Contains smooth muscle controlling vessel diameter; regulates blood flow and pressure via vasoconstriction and vasodilation.
  • Differences between arteries and veins
    Arteries have thicker tunica media and more elastic laminae; veins have larger lumens, thinner walls, and valves to prevent backflow.
  • Classification of arteries by size
    Elastic arteries (largest, near heart), muscular arteries (medium, distribute blood), arterioles (smallest, regulate flow to capillaries).
  • Baroreceptors and chemoreceptors
    Pressure receptors in aorta and carotid arteries detect blood pressure; chemoreceptors detect oxygen, carbon dioxide, and pH levels.
  • Vein characteristics
    Veins outnumber arteries, have larger lumens, thinner walls, less smooth muscle, and contain valves to prevent blood backflow.
  • Atherosclerosis
    Plaque buildup in arterial tunica intima caused by injury to endothelium; leads to vessel inflammation, narrowing, and risk of clots.
  • Hemodynamics
    Study of blood flow; blood moves down pressure gradients created by the heart; flow is proportional to pressure gradient and inversely proportional to resistance.
  • Effect of cross-sectional area on blood velocity
    As total cross-sectional area increases (in smaller vessels), blood velocity decreases, allowing efficient exchange in capillaries.
  • Factors determining blood pressure
    Blood pressure depends on cardiac output, peripheral resistance, and blood volume.
  • Peripheral resistance factors
    Resistance increases with smaller vessel radius, higher blood viscosity, and longer vessel length.
  • Cardiac output formula
    Cardiac output (CO) = stroke volume × heart rate; CO influences blood pressure.
  • Mean arterial pressure (MAP) calculation
    MAP ≈ diastolic pressure + 1/3 (systolic pressure − diastolic pressure); average pressure in systemic arteries.
  • Pulse pressure
    Difference between systolic and diastolic pressures; reflects force generated by heart during contraction.
  • Venous return mechanisms
    Venous valves prevent backflow; skeletal muscle pump and respiratory pump assist blood return to heart.
  • Varicose veins
    Dilated, bulging veins caused by valve failure and blood pooling, often in lower limbs.
  • Short-term blood pressure regulation
    Autonomic nervous system adjusts heart rate and vessel diameter; sympathetic increases BP via vasoconstriction and increased CO; parasympathetic decreases BP.
  • Baroreceptor reflex
    Negative feedback loop where baroreceptors detect BP changes and medulla adjusts autonomic output to restore normal BP.
  • Vasovagal syncope
    Fainting caused by sudden parasympathetic activation and sympathetic inhibition, leading to decreased cardiac output and vasodilation.
  • Hormones affecting blood pressure
    Epinephrine, norepinephrine, thyroid hormone increase CO and resistance; angiotensin-II causes vasoconstriction; ANP decreases resistance.
  • Long-term blood pressure regulation
    Kidneys regulate blood volume via urine output; hormones like ADH and aldosterone increase volume; ANP decreases volume.
  • Capillary exchange mechanisms
    Substances cross capillaries via diffusion through membranes, movement through pores, and transcytosis for larger molecules.
  • Types of capillaries
    Continuous (least leaky), fenestrated (pores for rapid exchange), sinusoidal (large gaps for blood cells and proteins).
  • Precapillary sphincters
    Smooth muscle rings controlling blood flow into true capillaries; regulate tissue perfusion.
  • Local autoregulation of tissue perfusion
    Myogenic mechanism adjusts resistance to maintain flow; metabolic controls dilate arterioles in response to low oxygen and high CO2.
  • Capillary hydrostatic and osmotic pressures
    Hydrostatic pressure pushes water out; osmotic pressure (mainly from plasma proteins) pulls water in; balance determines net filtration.
  • Edema causes
    Excess interstitial fluid due to increased hydrostatic pressure or decreased osmotic pressure, leading to swelling.