topic 4 pt 1

• What are the two major circulations of the cardiovascular system?

  Pulmonary and systemic circulations
• What is the primary function of the pulmonary circulation?

  To re-oxygenate the blood
• How does systemic circulation differ from pulmonary circulation?

  Systemic circulation has a long loop and high pressure, while pulmonary circulation has a short loop and low pressure
• Where is the heart located?

  In the mediastinum
• What structures are contained within the mediastinum?

  The heart, trachea, esophagus, thymus, blood vessels, and nerves
• What are the two layers of the serous pericardium?

  Parietal layer and visceral layer
• What is the function of the fibrous pericardium?

  For anchorage and protection
• What are the three layers of the heart wall?

  Epicardium, myocardium, and endocardium
• What is the role of the myocardium?

  Muscle contraction
• What is the function of the coronary arteries?

  To supply blood to the myocardium
• How does blood return from the myocardium?

  Via cardiac veins which drain into the coronary sinus
• What are the two types of heart valves?

  Atrioventricular valves and semi-lunar valves
• What is the function of the atrioventricular valves?

  To separate the atria from the ventricles
• What is the left AV valve also known as?

  Bicuspid or mitral valve
• What is the role of the semi-lunar valves?

  To separate the ventricles from the great vessels
• What is the significance of the dense connective tissue ring around the heart valves?

  It provides anchorage, structural stability, and electrical insulation
• What is the functional syncytium in cardiac muscle?

  A property allowing fast electrical conduction and coordinated contraction
• What type of energy do myocardial cells primarily use?

  Glucose and fatty acids
• What is the role of the sino-atrial (SA) node?

  It initiates the electrical signal that makes the heart contract
• What is the function of the atrio-ventricular (AV) node?

  To transmit electrical signals from the atria to the ventricles
• What is the purpose of the Purkinje fibers?

  For rapid electrical impulse conductance resulting in contraction
• What does autorythmicity refer to in the heart?

  The heart's ability to spontaneously depolarize and generate its own rhythm
• What are the phases of the cardiac cycle?

  Atrial systole, atrial diastole, ventricular systole, and ventricular diastole
• What happens during depolarization of the heart muscle?

  The membrane slowly depolarizes until it reaches threshold, triggering an action potential
• What is the resting membrane potential (RMP) of myocardial cells?

  Myocardial cells have a stable resting membrane potential
• What prevents premature re-excitation of cardiac muscle cells?

  The long period of depolarization during the action potential
• What does the electrocardiogram (ECG) measure?

  The sum of all electrical events as measured on the body surface
• What are the three main components of an ECG waveform?

  P wave, QRS complex, and T wave
• What does the P wave represent in an ECG?

  Atrial depolarization
• What does the QRS complex represent in an ECG?

  Ventricular depolarization
• What does the T wave represent in an ECG?

  Ventricular repolarization
• What is a lead in the context of an ECG?

  The arrangement of any two electrodes measuring electrical potential
• Why is Lead II commonly used to calculate heart rate?

  It provides the best signals for measurement
• What occurs during isovolumetric contraction in the cardiac cycle?

  The ventricles start to contract while the atria are relaxed
• What happens during ventricular ejection in the cardiac cycle?

  Blood leaves the ventricles as ventricular pressure increases
• What occurs during isovolumetric relaxation in the cardiac cycle?

  The ventricles begin to relax with closed semilunar and AV valves
• What happens during rapid ventricular filling in the cardiac cycle?

  The ventricles relax and AV valves open, allowing blood to fill
• What occurs during atrial systole in the cardiac cycle?

  The atria contract and add the final 20% of blood to the ventricular volume
• What do the pressure changes in the heart chambers indicate during the cardiac cycle?

  They indicate the mechanical events occurring in the heart
• What is the effect of contraction in the right atrium?

  It pushes remaining blood into the right ventricle