quiz cardiovascular physiology I
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Questions and Answers

What effect does increased venous return have on stroke volume?

  • Decreases stroke volume
  • Has no effect on stroke volume
  • Increases stroke volume (correct)
  • Causes irregular stroke volume

    • Which of the following factors directly increases contractility at any given preload?

  • Negative inotropic agents
  • Positive inotropic agents (correct)
  • Weak venous return
  • Increased afterload

    • What is the impact of hypertension on stroke volume?

  • Has no effect on stroke volume
  • Decreases stroke volume (correct)
  • Increases stroke volume
  • Causes erratic changes in stroke volume

    • The Frank-Starling law describes the relationship between which two cardiac aspects?

    <p>Preload and stroke volume</p> Signup and view all the answers

    How does increased sympathetic stimulation affect stroke volume?

    <p>Increases stroke volume</p> Signup and view all the answers

    Which condition is likely to decrease stroke volume due to increased afterload?

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

    What role do positive inotropic agents like epinephrine play in heart function?

    <p>Increase contractility</p> Signup and view all the answers

    Which of the following best describes contractility?

    <p>The strength of contraction at any given preload</p> Signup and view all the answers

    Which structure is primarily responsible for transporting lipids from the digestive organs to the bloodstream?

    <p>Lymphatic Capillaries</p> Signup and view all the answers

    What is the primary role of lymph nodes in the lymphatic system?

    <p>Defending against pathogens</p> Signup and view all the answers

    Which statement correctly describes the systemic circulation?

    <p>It ejects blood into the aorta.</p> Signup and view all the answers

    What is the function of valves in lymphatic capillaries?

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

    Which of the following structures is involved in gas exchange in the lungs?

    <p>Pulmonary capillaries</p> Signup and view all the answers

    What is the primary function of the coronary circulation?

    <p>To deliver oxygen to the heart muscle</p> Signup and view all the answers

    Which structure acts as the heart's natural pacemaker?

    <p>Sinoatrial (SA) node</p> Signup and view all the answers

    Which component of the lymphatic system helps in the maturation of T-cells?

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

    What fluid is formed when tissue fluid enters a lymphatic capillary?

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

    Which characteristics are unique to cardiac muscle fibers compared to skeletal muscle fibers?

    <p>Presence of intercalated discs</p> Signup and view all the answers

    What type of blood is ejected into the pulmonary trunk from the right side of the heart?

    <p>Oxygen-poor blood</p> Signup and view all the answers

    What is the role of autorhythmic fibers in the heart?

    <p>They generate action potentials for heart contractions</p> Signup and view all the answers

    Where does blood from the coronary veins empty into?

    <p>Coronary sinus</p> Signup and view all the answers

    Which phase of the cardiac action potential involves a plateau?

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

    What feature of cardiac muscle cells helps coordinate contractions?

    <p>Intercalated discs</p> Signup and view all the answers

    Which structure in the cardiac conduction system is responsible for transmitting action potentials to the ventricles?

    <p>Bundle of His</p> Signup and view all the answers

    What event in the cardiac cycle corresponds with the 'P' wave on the electrocardiogram?

    <p>Atrial depolarization</p> Signup and view all the answers

    During which phase of the cardiac cycle are the ventricles contracting?

    <p>Ventricular systole</p> Signup and view all the answers

    Which heart sound is produced by the closure of the AV valves?

    <p>'Lub'</p> Signup and view all the answers

    What formula represents Cardiac Output (CO)?

    <p>CO = stroke volume (SV) x heart rate (HR)</p> Signup and view all the answers

    How is Stroke Volume (SV) defined in the context of the cardiac cycle?

    <p>Volume of blood ejected from the left ventricle during systole</p> Signup and view all the answers

    Which electrocardiogram feature indicates the time between heartbeats?

    <p>R-R interval</p> Signup and view all the answers

    What is a common characteristic of atrial fibrillation as shown on an electrocardiogram?

    <p>No detectable P waves</p> Signup and view all the answers

    Which condition is indicated by irregular R-R intervals in the context of the cardiac cycle?

    <p>Atrial fibrillation</p> Signup and view all the answers

    What primarily causes the plateau phase during the action potential in a ventricular contractile fiber?

    <p>Ca2+ inflow through slow channels</p> Signup and view all the answers

    Which wave on an electrocardiogram (ECG) represents atrial depolarization?

    <p>P wave</p> Signup and view all the answers

    What does the P-R interval indicate?

    <p>Time for action potential to travel from the SA node to the AV node</p> Signup and view all the answers

    During which phase does rapid depolarization occur due to Na+ inflow?

    <p>Initial depolarization</p> Signup and view all the answers

    What does the T wave represent in an ECG?

    <p>Ventricular repolarization</p> Signup and view all the answers

    What is indicated by the QRS complex on an electrocardiogram?

    <p>Ventricular contraction</p> Signup and view all the answers

    What causes repolarization during the action potential in a ventricular contractile fiber?

    <p>Closure of Ca2+ channels and K+ outflow</p> Signup and view all the answers

    What is the function of the P-R segment on an ECG?

    <p>Represents conduction through the AV node</p> Signup and view all the answers

    Which hormones are specifically known to increase both heart rate and contractility?

    <p>Epinephrine and norepinephrine</p> Signup and view all the answers

    What role do cations play in heart function?

    <p>Ionic imbalance can compromise pumping effectiveness.</p> Signup and view all the answers

    According to the Frank–Starling law of the heart, cardiac muscle fibers:

    <p>Contract more forcefully within limits of stretching.</p> Signup and view all the answers

    What effect does an increase in preload have on the heart?

    <p>Increases cardiac output</p> Signup and view all the answers

    Which of the following factors is likely to lead to decreased afterload?

    <p>Decreased blood pressure in the aorta and pulmonary artery</p> Signup and view all the answers

    What is one effect of increased sympathetic stimulation on the heart?

    <p>Increased stroke volume</p> Signup and view all the answers

    Under what condition is the sympathetic nervous system most likely to stimulate the heart?

    <p>During physical exertion</p> Signup and view all the answers

    Which population might experience increased heart rate due to hormonal influences and not solely from physical factors?

    <p>Infants and senior citizens</p> Signup and view all the answers

    Study Notes

    Cardiovascular System (Part I) - Study Notes

    • Learning Objectives:
      • Describe the composition of blood
      • Describe the basic functions of the cardiovascular system
      • Explain cardiac circulation
      • Describe the electrical conducting system of the heart
      • Explain the role of calcium in cardiac muscle contraction and relate to the action potential graph
      • Explain the ECG
      • Describe the cardiac cycle, factors influencing cardiac output, stroke volume, and heart rate

    Blood - Remarkable Fluid

    • Composition:

      • Plasma (55% by volume): Primarily water (91%), proteins (7%), other solutes (2%)
      • Formed elements (45% by volume):
        • Red blood cells (erythrocytes): 4.2-6.2 million/mm³
        • White blood cells (leukocytes): 5-9 thousand/mm³ (Granulocytes: Neutrophils, Eosinophils, Basophils; Agranulocytes: Monocytes, Lymphocytes)
        • Platelets (thrombocytes): 250-400 thousand/mm³

    • Key components and percentages by weight:

      • Albumins: 58%
      • Globulins: 38%
      • Fibrinogen: 4%
      • Ions: Small percentage
      • Nutrients
      • Waste products
      • Regulatory substances
      • Gases

    Components of Blood

    • Connective tissue
    • Red blood cells (erythrocytes): Oxygen transport
    • White blood cells (leukocytes): Immune function (different types with varying functions)
    • Platelets (thrombocytes): Essential for blood clotting
    • Plasma: Fluid component, 55% of blood

    Blood Plasma

    • Composition: Primarily water, and a mixture of proteins (albumin, globulins, fibrinogen), nutrients, amino acids, glucose, nucleotides, lipids, gases, electrolytes, and waste products

    Functions of Blood

    • Transportation: Carries oxygen, nutrients, hormones, and waste products
    • Regulation: Maintains homeostasis (pH, temperature, fluid balance)
    • Protection: Fights infection, prevents blood loss

    Red Blood Cells

    • Shape: Biconcave discs for efficient gas exchange
    • Function: Transport oxygen throughout the body
    • Hemoglobin: Iron-containing pigment; carries oxygen (bright red when oxygenated, darker red when deoxygenated)

    White Blood Cells

    • Granulocytes:
      • Neutrophils (55%): Phagocytosis (destroy bacteria and toxins)
      • Eosinophils (3%): Combat parasites and regulate allergic reactions
      • Basophils (1%): Release histamine (inflammation)
    • Agranulocytes:
      • Monocytes (8%): Develop into macrophages (phagocytosis)
      • Lymphocytes (33%): Diverse roles in adaptive immunity

    Blood Platelets

    • Function: Crucial in blood clotting (hemostasis)
    • Number: 130,000-360,000 per cubic millimeter of blood

    Controlling Bleeding

    • Hemostasis: The stoppage of bleeding
    • Processes:
      • Blood vessel spasm
      • Formation of platelet plug
      • Blood coagulation (complex cascade of clotting factors)

    Blood Vessels

    • Arteries and Arterioles:
      • Carry blood away from the heart under high pressure
      • Strongest vessels with thick walls
    • Veins and Venules:
      • Carry blood towards the heart under low pressure
      • Have valves to prevent backflow
    • Capillaries:
      • Connect arterioles to venules
      • Thin walls for efficient diffusion of oxygen and nutrients

    The Lymphatic System

    • Function:
      • Collects interstitial fluid (lymph)
      • Returns lymph to the bloodstream
      • Transports lipids from the digestive system
      • Defends against disease-causing agents (pathogens)

    Lymph Fluid

    • Origin: Tissue fluid that enters lymphatic capillaries
    • Structure: Contains valves to prevent backflow

    Circulation of Blood

    • Function: Transport oxygen and nutrients to all parts of the body, removing waste products
    • Systemic circuit: Transports blood to and from the body
    • Pulmonary circuit: Transports blood to and from the lungs for gas exchange

    Systemic and Pulmonary Circulation

    • Systemic circulation:
      • Blood flows from the left ventricle, through arteries, to capillaries where gas and nutrient exchange occurs, to the veins which bring the deoxygenated blood back to the right atrium
    • Pulmonary circulation:
      • Blood flows from the right ventricle, to the lungs where gas exchange occurs, and returns to the left atrium as oxygenated blood.

    Coronary Circulation

    • Coronary arteries: Branch from the aorta, providing oxygenated blood to the heart muscle
    • Anastomoses: Provide alternative routes for blood flow if major arteries are blocked
    • Coronary veins: Collect deoxygenated blood and drain into the coronary sinus, which flows into the right atrium

    Heart: A Special Muscle

    • Cardiac muscle characteristics:
      • Shorter and less circular than skeletal muscle
      • Branched fibers with intercalated discs
      • Single, centrally located nuclei
      • Contains many mitochondria (high energy demand)

    Autorhythmic Fibers

    • Specialized cardiac muscle fibers that generate and conduct electrical signals
    • Self-excitable (initiate their own action potentials)
      • Generate action potentials repeatedly for heart contractions
    • Form the heart's conduction system (pathway of electrical signals)

    Cardiac Conduction System

    • Components:
      • Sinoatrial (SA) node
      • Atrioventricular (AV) node
      • Bundle of His
      • Right and left bundle branches
      • Purkinje fibers

    Action Potentials and Contraction

    • Depolarization: Inward movement of ions, causing contraction
    • Plateau: Prolonged period of depolarization (maintained by calcium channels)
    • Repolarization: Return to resting membrane potential

    Electrocardiogram (ECG)

    • Composite recording of action potentials from all heart muscle fibers
    • Waveforms (P, QRS, T) reflect specific electrical events in the heart
      • P-wave: atrial depolarization
      • QRS complex: ventricular depolarization
      • T-wave: ventricular repolarization

    Cardiac Cycle

    • The sequence of events in one complete heartbeat
    • Phases:
      • Atrial systole (contraction of atria)
      • Ventricular systole (contraction of ventricles)
      • Atrial and ventricular diastole (relaxation of all chambers)

    Heart Sounds

    • Auscultation: Listening to heart sounds
    • "Lub" sound: Closure of atrioventricular valves
    • "Dup" sound: Closure of semilunar valves

    Cardiac Output (CO)

    • Definition: Volume of blood ejected by the left ventricle per minute
    • Calculation: CO = stroke volume (SV) × heart rate (HR)

    Stroke Volume (SV)

    • Amount of blood ejected from the ventricles with each contraction

    • Factors regulating SV:

      • Preload (degree of stretching)
      • Contractility (strength of contraction)
      • Afterload (pressure against which ventricles pump)

    • Preload: Determined by venous return (blood returning to the heart)

    • Contractility: Influenced by hormones (epinephrine, norepinephrine) and ions

    • Afterload: Determined by arterial pressure

    Regulation of Heartbeat

    • Autonomic nervous system (ANS):
      • Sympathetic: Increases heart rate and force of contraction
      • Parasympathetic: Decreases heart rate
    • Hormonal factors: Epinephrine and thyroid hormones increase heart rate and contractility
    • Ionic factors: An imbalance of ions can compromise the effectiveness of pumping blood

    Exercise and the Heart

    • Increased heart rate during exercise is a physiological response enabling more efficient oxygen and nutrient delivery to tissues and removal of metabolic wastes.

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