Cardiovascular Physiology Quiz
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Questions and Answers

What are the functional components of the cardiovascular system?

  • Heart, Kidneys, & Blood
  • Heart, Blood Vessels, & Blood (correct)
  • Heart, Blood Vessels, & Vessels

    • What is the purpose of the heart?

    The heart is the pump that circulates blood throughout the body.

    What are the four features of the functional anatomy of the heart necessary to create the "pump"?

  • Cardiac Muscle, Myocardium, & Valves
  • Cardiac Muscle, Chambers, Valves, & Intrinsic Conduction System (correct)
  • Cardiac Muscle, Chambers, & Valves

    • Which of the following is NOT a characteristic of cardiac muscle?

    <p>Multinucleate</p> Signup and view all the answers

    How many chambers are present in the heart?

    <p>Four</p> Signup and view all the answers

    What are the two systems of the heart?

    <p>Pulmonary &amp; Systemic</p> Signup and view all the answers

    What is the primary purpose of the valves?

    <p>To prevent backflow.</p> Signup and view all the answers

    What are the two types of valves that prevent backflow in the heart?

    <p>Atrioventricular Valves &amp; Semilunar Valves</p> Signup and view all the answers

    What is the function of the intrinsic conduction system?

    <p>The intrinsic conduction system coordinates the contraction of the atria and ventricles.</p> Signup and view all the answers

    What are the two main types of myocardial cells?

    <p>Autorhythmic Cells &amp; Contractile Cells</p> Signup and view all the answers

    What makes autorhythmic cells unique compared to contractile cells?

    <p>Autorhythmic cells are smaller, lack organized sarcomere structure, and have an unstable membrane potential.</p> Signup and view all the answers

    What is the key difference between the action potential of a contractile cell and a typical neuron?

    <p>The action potential of a contractile cell is longer in duration.</p> Signup and view all the answers

    What is the significance of the plateau phase in the action potential of contractile cells?

    <p>A longer plateau phase prevents summation and tetanus.</p> Signup and view all the answers

    How does sympathetic activity affect pacemaker cells?

    <p>Sympathetic activity increases the rate of action potentials and stimulates faster depolarization.</p> Signup and view all the answers

    What are the specialized junctions found in intercalated discs?

    <p>Both A &amp; B</p> Signup and view all the answers

    What is the primary cause of the extended refractory period in cardiac muscle?

    <p>The influx of calcium ions.</p> Signup and view all the answers

    What are the steps involved in excitation-contraction coupling?

    <ol> <li>Action potential spreads along the sarcolemma. 2. Calcium enters the cell and binds to troponin.</li> </ol> Signup and view all the answers

    What is the difference between the contractile response of skeletal muscle and cardiac muscle?

    <p>Skeletal muscle contracts in an all-or-none fashion, while cardiac muscle contraction is graded.</p> Signup and view all the answers

    Why does cardiac muscle have a length-tension relationship?

    <p>Cardiac muscle generates the strongest contraction when stretched between 80% and 100% of its maximum length, due to the filling of chambers with blood.</p> Signup and view all the answers

    What is the mechanism by which cardiac muscle relaxes?

    <p>Calcium is transported back into the SR, and excess calcium is transported out of the cell by a sodium-calcium exchanger (NCX).</p> Signup and view all the answers

    What is the cardiac cycle?

    <p>The cardiac cycle is the sequence of events as blood enters the atria, leaves the ventricles, and then starts over.</p> Signup and view all the answers

    What is the role of the intrinsic electrical conduction system in the cardiac cycle?

    <p>The intrinsic electrical conduction system synchronizes the cardiac cycle.</p> Signup and view all the answers

    What are the two regulatory factors that influence the rate of the cardiac cycle?

    <p>Both A &amp; B</p> Signup and view all the answers

    What is the primary initiator of the cardiac cycle?

    <p>The Sino-Atrial node (SA node)</p> Signup and view all the answers

    What is the purpose of the delay at the AV node?

    <p>The delay at the AV node allows for complete atrial emptying before ventricular contraction.</p> Signup and view all the answers

    What is the function of the Purkinje fibers?

    <p>To conduct electrical impulses to the ventricles.</p> Signup and view all the answers

    What is the ECG?

    <p>The ECG is a recording of electrical activity in the heart.</p> Signup and view all the answers

    What does each wave in an ECG represent?

    <p>P wave: atrial depolarization; QRS complex: ventricular depolarization; T Wave: ventricular repolarization</p> Signup and view all the answers

    What is systole?

    <p>Systole is the period of contraction in the cardiac cycle.</p> Signup and view all the answers

    What are the phases of the cardiac cycle?

    <p>Rest, Atrial Systole, Isovolumetric Ventricular Contraction, Ventricular Ejection, &amp; Isovolumetric Ventricular Relaxation</p> Signup and view all the answers

    What causes the first heart sound (lub)?

    <p>The first heart sound (lub) is caused by the closure of the AV valves.</p> Signup and view all the answers

    What causes the second heart sound (dup)?

    <p>The second heart sound (dup) is caused by the closure of the semilunar valves.</p> Signup and view all the answers

    What is stroke volume?

    <p>The amount of blood pumped by the left ventricle in one contraction.</p> Signup and view all the answers

    The stroke volume is equal to the total amount of blood contained in the left ventricle.

    <p>False</p> Signup and view all the answers

    What is the name of the point where the heart is relaxed and the ventricles passively fill?

    <p>Late diastole</p> Signup and view all the answers

    What is the role of atrial systole in the cardiac cycle?

    <p>Atrial systole is the brief contraction of the atria that pushes a small amount of additional blood into the ventricles.</p> Signup and view all the answers

    What happens during isovolumetric ventricular contraction?

    <p>During isovolumetric ventricular contraction, the ventricles begin contracting, increasing pressure within the chambers, causing the AV valves to close, but not generating enough pressure to open the semilunar valves.</p> Signup and view all the answers

    What happens during ventricular ejection?

    <p>During ventricular ejection, the pressure within the ventricles rises above aortic pressure, causing the semilunar valves to open, and blood is expelled from the heart into the arteries.</p> Signup and view all the answers

    What happens during isovolumetric ventricular relaxation?

    <p>During isovolumetric ventricular relaxation, the ventricles relax, the pressure inside the chambers drops below aortic pressure, resulting in the closure of the semilunar valves, generating the second heart sound (dup).</p> Signup and view all the answers

    What happens during the back to atrial and ventricular diastole?

    <p>The cardiac cycle repeats as both the atria and ventricles relax, and the left ventricle passively fills again, starting the cycle anew.</p> Signup and view all the answers

    Study Notes

    Cardiovascular Physiology

    • Cardiovascular system function includes transportation of substances via blood and regulation of the system itself.
    • Protection from blood loss and synthesis of essential components are also functions.
    • The heart's functional anatomy is crucial to its pumping function.
    • Important components include cardiac muscle, chambers, valves, and intrinsic conduction system.

    Functional Anatomy of the Heart

    • The heart has four chambers: two atria and two ventricles.
    • It also involves two systems: pulmonary and systemic.

    Myocardial Physiology

    • Autorhythmic cells (pacemaker cells): These cells are smaller than contractile cells and lack organized sarcomeres. They don't contribute to heart force and have unstable membrane potentials.

    • Contractile cells: These cells exhibit characteristics of intercalated discs ( highly convoluted junctions with desmosomes and fascia adherens) and more mitochondria, and less sarcoplasmic reticulum than skeletal muscle.

    • Characteristics of Pacemaker Cells:

      • Smaller than contractile cells
      • Lack many myofibrils
      • Have no organized sarcomere structure
      • Don't contribute to the contractile force of the heart

    • Characteristics of Pacemaker Cells (cont.):

      • Unstable membrane potential fluctuates from -60 mV to -40 mV.
      • Slow leakage of K+ out and Na+ in cause slow depolarization.
      • Opening of funny (If) channels contributes
      • Opening of Ca²⁺ channels causes rapid depolarization,
      • Slow K⁺ channels cause repolarization.

    • Altering Pacemaker Cell Activity (Sympathetic):

      • Activation of β₁ adrenergic receptors increases cAMP.
      • This increases the If channel activity, leading to faster pacemaker potential and increased rate of action potentials

    • Altering Pacemaker Cell Activity (Parasympathetic):

      • Acetylcholine (ACh) binding to muscarinic receptors increases K⁺ permeability and decreases Ca²⁺ permeability.
      • This hyperpolarizes the membrane, delaying the time it takes to reach threshold and thus, decreasing the rate of action potentials.

    Myocardial Physiology Contractile Cells

    • Action potential of a contractile cell:

      • Ca²⁺ plays a primary role in the action potential lasting longer than a "normal" action potential.
      • Phases: resting membrane potential (-90mV), depolarization, temporary repolarization, plateau phase (with voltage-gated Ca²⁺ channels open), and repolarization.

    • Plateau Phases Importance:

      • Inhibits summation of cardiac contractions (prevents tetanus) because of the elongated refractory period.

    • Skeletal Muscle vs. Cardiac Muscle APs:

      • Skeletal muscle APs are very brief compared to the time required to develop tension.
      • Cardiac muscle APs have a plateau phase. This means their refractory period lasts almost as long as the entire muscle twitch, preventing tetanus. This is vital for the heart's continuous pumping action.

    • Excitation-Contraction Coupling (Contractile Cells):

      • Action potentials spread through the T-tubules and trigger the opening of voltage-gated L-type Ca²⁺ channels.
      • Ca²⁺ influx stimulates release of Ca²⁺ from the sarcoplasmic reticulum (SR). This is a Ca²⁺-induced Ca²⁺ release.
      • Ca²⁺ ions bind to troponin, initiating the cross-bridge cycle of contraction.

    • Contraction Strength: The strength of myocardial contraction is graded based on the level of cytosolic Ca²⁺ and the length-tension relationship.

    • Myocardial Relaxation:

      • Ca²⁺ ions are pumped back into the SR through the Na⁺/Ca²⁺ exchanger (NCX).

    Cardiac Cycle

    • The cardiac cycle is a sequence of events from blood entering atria, to leaving ventricles.

    • The heart's intrinsic electrical conduction pathway controls synchronization between chambers.

    • The heart uses the sympathetic and parasympathetic nervous systems to influence heart rate and conduction rate.

    • The electrical activity of the heart leads to recordable changes in body fluids.

    • ECG (Electrocardiogram): A recording of electrical activity in the heart, that reflects the depolarization/repolarization of heart cells.

    • Phases of the Cardiac Cycle:

      • Rest/Diastole: Both atria and ventricles are relaxed.
      • Atrial Systole: Atria contract, pushing blood into ventricles.
      • Isovolumetric ventricular contraction: The ventricles contract, increasing pressure, causing AV valves to close. The volume remains constant.
      • Ventricular ejection: Pressure in ventricles exceeds pressure in arteries, causing the semilunar valves to open. Blood is ejected.
      • Isovolumetric ventricular relaxation: Ventricular pressure drops below aortic pressure, causing semilunar valves to close, the second heart sound (dup).

    • Stroke Volume (SV): The amount of blood pumped by one ventricle per contraction. 

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    Cardiovascular Physiology PDF

    Description

    Test your knowledge on the functions and anatomy of the cardiovascular system, focusing on the heart's structure and myocardial physiology. This quiz covers topics including heart chambers, cardiac muscle, and autorhythmic cells.

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