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Cardiovascular System: The Heart - Anatomy & Physiology

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Terms in this set (28)

  • What are the four chambers of the heart?

    The heart has two superior atria and two inferior ventricles.

  • What separates the atria and ventricles internally?

    The interatrial septum separates the atria, and the interventricular septum separates the ventricles.

  • What is the function of the pericardium?

    The pericardium is a double-walled sac that protects the heart, anchors it to surrounding structures, and prevents overfilling.

  • Name the three layers of the heart wall.

    Epicardium (visceral serous pericardium), myocardium (cardiac muscle layer), and endocardium (inner endothelial lining).

  • What is the role of the fibrous cardiac skeleton in the myocardium?

    It anchors cardiac muscle fibers, supports heart valves and great vessels, and limits spread of action potentials to specific pathways.

  • What are the two types of heart valves and their locations?

    Atrioventricular (AV) valves between atria and ventricles; Semilunar (SL) valves between ventricles and major arteries (aorta and pulmonary trunk).

  • What prevents AV valve cusps from everting into the atria?

    Chordae tendineae anchor valve cusps to papillary muscles, holding them closed during ventricular contraction.

  • How do semilunar valves function?

    They prevent backflow from arteries into ventricles by opening when ventricular pressure rises and closing when it falls.

  • What is the significance of the heart being a double pump?

    Each side of the heart pumps blood to its own circuit: the right side to the pulmonary circuit and the left side to the systemic circuit.

  • Describe the anatomical difference between the right and left ventricles.

    The right ventricle is thinner and crescent-shaped; the left ventricle is thicker and round-shaped, wrapping around the right ventricle.

  • What is the function of intercalated discs in cardiac muscle?

    They contain desmosomes and gap junctions that mechanically and electrically connect cardiac muscle cells, enabling synchronized contraction.

  • How does cardiac muscle differ from skeletal muscle in physiology?

    Cardiac muscle cells are self-excitable, contract as a unit, have longer action potentials with a plateau phase, and rely almost exclusively on aerobic respiration.

  • What is the intrinsic conduction system of the heart?

    A network of autorhythmic cells that initiate and distribute impulses to coordinate heart depolarization and contraction.

  • List the sequence of excitation in the intrinsic conduction system.

    1. Sinoatrial (SA) node → 2. Atrioventricular (AV) node → 3. AV bundle (bundle of His) → 4. Right and left bundle branches → 5. Purkinje fibers (subendocardial conducting network).

  • What is the role of the SA node?

    The SA node is the heart's pacemaker, generating impulses about 75 times per minute to set the heart's rhythm.

  • How does the autonomic nervous system regulate heart rate?

    The sympathetic nervous system increases heart rate and contractility; the parasympathetic nervous system decreases heart rate via the vagus nerve.

  • Describe the phases of the cardiac cycle.

    Includes ventricular filling, isovolumic contraction, ventricular ejection, and isovolumic relaxation, coordinating blood flow through the heart.

  • What causes the 'lub-dup' heart sounds?

    First sound (lub) is closing of AV valves; second sound (dup) is closing of semilunar valves during the cardiac cycle.

  • Define stroke volume and cardiac output.

    Stroke volume (SV) is the volume of blood pumped per beat; cardiac output (CO) is SV multiplied by heart rate (HR), representing blood pumped per minute.

  • What factors regulate stroke volume?

    Preload (degree of muscle stretch), contractility (strength of contraction), and afterload (arterial pressure opposing ejection).

  • What is the Frank-Starling law of the heart?

    Increased preload (stretch) leads to increased stroke volume due to optimal overlap of cardiac muscle fibers.

  • How does contractility affect stroke volume?

    Increased contractility lowers end systolic volume and increases stroke volume by enhancing calcium availability for contraction.

  • What is afterload and how does it affect the heart?

    Afterload is the pressure ventricles must overcome to eject blood; increased afterload (e.g., hypertension) raises end systolic volume and reduces stroke volume.

  • What are positive and negative chronotropic factors?

    Positive chronotropic factors increase heart rate; negative chronotropic factors decrease heart rate.

  • How do hormones influence heart rate?

    Epinephrine and norepinephrine increase heart rate and contractility; thyroxine increases heart rate and enhances effects of catecholamines.

  • What are common clinical conditions related to heart rate abnormalities?

    Tachycardia: abnormally fast heart rate; Bradycardia: abnormally slow heart rate, which can be normal in athletes or pathological.

  • What is congestive heart failure (CHF)?

    A condition where cardiac output is insufficient to meet tissue needs, caused by weakened myocardium from factors like coronary atherosclerosis or high blood pressure.

  • What are the two fetal heart structures that bypass pulmonary circulation?

    Foramen ovale connects atria; ductus arteriosus connects pulmonary trunk to aorta; both close after birth.