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Anatomy & Physiology: Blood Vessels and Circulation

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Terms in this set (20)

  • Types of blood vessels and their functions
    Arteries carry blood away from the heart; Arterioles are small arteries leading to capillaries; Capillaries are sites of exchange; Venules collect blood from capillaries; Veins return blood to the heart.
  • Layers of blood vessel walls
    From inside out: Tunica intima (inner layer), Tunica media (smooth muscle layer), Tunica externa (outer connective tissue layer).
  • Differences between arteries and veins
    Arteries have thicker walls, higher pressure, smaller round lumen, folded endothelium, and are more elastic. Veins have larger irregular lumen and valves to prevent backflow.
  • Arterial diameter control mechanisms
    Vasoconstriction: contraction of arterial smooth muscle; Vasodilation: relaxation enlarging lumen; both controlled by sympathetic nervous system.
  • Types of arteries from heart to capillaries
    Elastic arteries (large, many elastic fibers), Muscular arteries (medium-sized, many muscle cells), Arterioles (smallest, thin or incomplete tunica media).
  • Characteristics of veins
    Veins have larger diameter, thinner walls, lower pressure, valves to prevent backflow, and rely on skeletal muscle and respiratory pumps to assist blood return.
  • Function of venous valves
    Folds of tunica intima that prevent blood from flowing backward, aiding venous return especially in limbs.
  • Capillary structure and function
    Capillaries are smallest vessels with thin endothelial walls, no tunica media or externa, and are sites of exchange between blood and interstitial fluid.
  • Capillary beds and blood flow regulation
    Capillary beds connect arterioles and venules; precapillary sphincters open/close to regulate blood flow in pulses.
  • Mechanisms of capillary exchange
    Materials move by diffusion, filtration (fluid out at arterial end), and reabsorption (fluid in at venous end).
  • Factors influencing blood pressure
    Total peripheral resistance depends on vascular resistance, blood viscosity, and turbulence.
  • Definition of systolic and diastolic pressure
    Systolic pressure: peak arterial pressure during ventricular contraction; Diastolic pressure: minimum arterial pressure during relaxation.
  • Mean arterial pressure (MAP) formula
    MAP = Diastolic pressure + one-third of pulse pressure, where pulse pressure = systolic - diastolic.
  • Role of cardiovascular center in blood pressure regulation
    Located in medulla oblongata; includes cardioacceleratory and cardioinhibitory centers and vasomotor center controlling vessel diameter.
  • Hormones affecting cardiovascular regulation
    Epinephrine and norepinephrine increase cardiac output and vasoconstriction; ADH, aldosterone, erythropoietin, ANP, and BNP also modulate blood volume and pressure.
  • Blood flow priority to the brain
    Brain has high oxygen demand; cerebral vessels dilate when peripheral vessels constrict to maintain constant blood flow.
  • Pulmonary circuit blood flow path
    Deoxygenated blood from right atrium → right ventricle → pulmonary trunk → pulmonary arteries → lungs → pulmonary veins → left atrium.
  • Systemic circuit blood flow path
    Oxygenated blood from left ventricle → ascending aorta → systemic arteries → capillaries → systemic veins → vena cava → right atrium.
  • Major branches of the aortic arch
    Brachiocephalic trunk (right subclavian and right common carotid), left common carotid artery, and left subclavian artery.
  • Differences between fetal and adult circulation
    Fetal lungs nonfunctional; blood bypasses lungs via foramen ovale and ductus arteriosus; placenta provides oxygen; at birth, these shunts close.