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Anatomy & Physiology: Cardiovascular System and Cardiac Function

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Terms in this set (28)

  • What drives blood flow through the cardiovascular system?
    Blood flows due to pressure gradients, moving from areas of higher pressure to lower pressure.
  • What are the main components of the cardiovascular system?
    The heart (pump), blood vessels (arteries, veins, capillaries), and blood (cells and plasma).
  • Describe the difference between systemic and pulmonary circulation.
    Systemic circulation carries oxygenated blood to the body and returns deoxygenated blood to the heart; pulmonary circulation carries deoxygenated blood to the lungs and returns oxygenated blood to the heart.
  • What is the relationship between flow, pressure gradient, and resistance?
    Flow is directly proportional to the pressure gradient and inversely proportional to resistance: \(Flow \propto \frac{\Delta P}{R}\).
  • How does vessel radius affect resistance and flow?
    Resistance is inversely proportional to the fourth power of the radius: \(R \propto \frac{1}{r^4}\). Small changes in radius cause large changes in resistance and flow.
  • What are the four chambers of the heart and their functions?
    Right atrium and ventricle receive and pump deoxygenated blood to lungs; left atrium and ventricle receive and pump oxygenated blood to the body.
  • What is the role of heart valves?
    Valves ensure one-way blood flow: atrioventricular valves separate atria and ventricles; semilunar valves guard exits of ventricles.
  • What are the two types of myocardial cells?
    Contractile cells generate force for pumping; autorhythmic cells initiate and conduct electrical signals.
  • How does cardiac excitation-contraction coupling differ from skeletal muscle?
    Cardiac muscle relies on extracellular Ca entry triggering Ca release from the SR (calcium-induced calcium release), unlike skeletal muscle which uses mechanical coupling.
  • What is the significance of the plateau phase in cardiac contractile cell action potentials?
    The plateau phase (Phase 2) is caused by Ca influx, prolonging the action potential and refractory period, preventing tetanus.
  • Describe the heart's electrical conduction pathway.
    SA node → atria → AV node → bundle of His → bundle branches → Purkinje fibers → ventricular myocardium.
  • What does the P wave, QRS complex, and T wave represent on an ECG?
    P wave: atrial depolarization; QRS complex: ventricular depolarization; T wave: ventricular repolarization.
  • What is cardiac output and how is it calculated?
    Cardiac output (CO) is the volume of blood pumped per minute: \(CO = HR \times SV\), where HR is heart rate and SV is stroke volume.
  • What factors influence stroke volume?
    Stroke volume depends on preload (EDV), contractility, and afterload (arterial resistance).
  • Explain the Frank-Starling law of the heart.
    Increased ventricular filling (preload) stretches cardiac muscle fibers, leading to a stronger contraction and increased stroke volume.
  • How does the autonomic nervous system regulate heart rate?
    Parasympathetic stimulation decreases heart rate via acetylcholine; sympathetic stimulation increases heart rate and contractility via norepinephrine and epinephrine.
  • What is afterload in cardiac physiology?
    Afterload is the resistance the ventricle must overcome to eject blood, influenced by arterial blood pressure and vascular resistance.
  • What is the role of coronary circulation?
    Coronary arteries supply oxygen-rich blood to the heart muscle; coronary veins return deoxygenated blood to the right atrium.
  • How do beta-blockers affect the heart?
    Beta-blockers block β₁-adrenergic receptors, reducing heart rate and contractility, lowering oxygen demand after heart attacks.
  • What causes heart sounds 'lub' and 'dup'?
    'Lub' (S1) is caused by AV valve closure at ventricular contraction start; 'dup' (S2) is caused by semilunar valve closure at ventricular relaxation start.
  • What is the significance of the long refractory period in cardiac muscle?
    It prevents summation and tetanus, ensuring the heart relaxes fully before the next contraction.
  • How does blood velocity relate to flow rate and vessel cross-sectional area?
    Velocity = Flow rate / Cross-sectional area; velocity increases in narrower vessels if flow is constant.
  • What is the function of intercalated disks in cardiac muscle?
    Intercalated disks contain desmosomes for mechanical strength and gap junctions for electrical coupling, enabling coordinated contraction.
  • What is the effect of vasoconstriction and vasodilation on blood flow?
    Vasoconstriction decreases vessel radius, increasing resistance and decreasing flow; vasodilation increases radius, decreasing resistance and increasing flow.
  • What is the role of the AV node delay in cardiac conduction?
    The AV node delay allows atria to finish contracting before ventricles contract, ensuring efficient blood flow.
  • What is the ejection fraction and how is it calculated?
    Ejection fraction is the percentage of EDV ejected per beat: \(EF = \frac{SV}{EDV} \times 100\%\).
  • How does calcium removal occur during cardiac muscle relaxation?
    Ca is pumped back into the SR by Ca-ATPase and removed from the cell by the Na-Ca exchanger (NCX).
  • What is the clinical significance of elevated blood troponin levels?
    Elevated troponin indicates heart muscle damage, such as from myocardial infarction.