Block 1

• Cardiovascular Circulation


  The cardiovascular system has three components: 1. The Heart, 2. Blood, 3. Vasculature (Blood Vessels)

  
• Systemic circuit (aka "SystemicCirculation")


  Carries oxygen &nutrients to the cells of our body
• Pulmonary circuit (aka "PulmonaryCirculation")


  Reloads blood with oxygen

  
• Circulation is continuous
• The heart is a (double) pump; blood makes two trips through the heart
• Each stop at the heart is the end of a separate circuit (heart → arteries → capillaries → veins →heart)
• Systemic Circuit (Systemic Circulation)

  Carries oxygenated blood ("arterial blood") to body cells/tissues/organs

  
• Pulmonary Circuit (Pulmonary Circulation)


  Carries de-oxygenated blood ("venous blood") to the lungs where it is reloaded with oxygen (and emptied of excess carbon dioxide) before returning to the heart

  
• Cardiac Output (CO)


  The amount of blood pumped by a ventricle per unit time (measured in L/min)

  
• Cardiac Output is the same for both systemic & pulmonary circuits (right & left ventricles eject same amount of blood)

  
• Cardiac Output is equal to about ***5 L/min*** under resting conditions
• Cardiac Output can be increased to as much as 40 L/min during maximal exercise (in elite athletes)
• The Heart


  Is composed primarily of cardiac muscle (i.e. cardiomyocytes), is a (double) pump, contains 4 chambers, directs blood flow by means of 4 valves, is supplied with blood by the first two arteries formed off the aorta

  
• Chambers of the Heart

  • The Right Atrium (RA)
  • The Left Atrium (LA)
  • The Right Ventricle (RV)
  • The Left Ventricle (LV)
• The atria receive blood; the ventricles force blood out of the heart into systemic & pulmonary circuits

  
• Due to differences in workload, the left ventricle has much more muscle (is much thicker) than the right ventricle
• Heart Valves


  There are four "one-way" heart valves that ensure blood flows through the heart in only one direction
• Heart Valves


  • 2 atrioventricular valves (between each set of atria & ventricles)
  • 2 semilunar valves (one between LV & aorta, and the other between RV & pulmonary trunk)

  
• Left AV valve


  Bicuspid valve ("two cusps"), mitral valve, separates left atrium & left ventricle
• Right AV valve


  Tricuspid valve ("three cusps"), separates right atrium & right ventricle
• Chordae tendinae


  Tendons that attach the valve cusps to the inner ventricular walls to prevent "prolapse" of the valves into the atria during ventricular contraction
• Papillary muscles


  Specialized muscles that regulate tension in the chordae tendinae and contract simultaneously with the ventricles
• Aortic semilunar valve


  Separates the left ventricular chamber from the aorta
• Pulmonary semilunar valve


  Separates the right ventricular chamber from the pulmonary trunk/artery

  
• Semilunar valves open in a pressure-dependent manner, meaning that they open and close in response to pressure differences between the major vessels and the heart ventricles
• AV valves open & close together, and semilunar valves open & close together, for coordinated heart valve function
• Coronary Circulation


  The part of systemic circulation that provides the heart tissue itself with blood

  
• Right Coronary Artery


  Originates on ascending aorta, supplies SA node, AV node, parts of RA, interventricular septum, & both ventricles
• Left Coronary Artery


  Originates on left ascending aorta, supplies SA node, left atrium, interventricular septum, and both ventricles
• Great cardiac vein


  Drains the anterior heart
• Middle cardiac vein


  Drains the posterior heart
• Coronary sinus


  Drains the great and middle cardiac veins into the right atrium
• The right ventricle pumps oxygen-poor blood to the lungs via the pulmonary trunk.
• The right atrium receives deoxygenated blood from the body through the superior vena cava (SVC) and inferior vena cava (IVC).
• The heart is located between the lungs, with its base on the left side.
• The right ventricle pumps oxygen-poor blood to the lungs via the pulmonary trunk.
• The left ventricle pumps oxygen-rich blood from the lungs to the rest of the body via the aorta.
• The right atrium receives deoxygenated blood from the vena cavae and passes it through the tricuspid valve to the right ventricle.
• The pericardium is a double-layered sac that surrounds the heart and contains serous fluid.
• The left atrium receives oxygenated blood from the pulmonary veins and passes it through the bicuspid (mitral) valve to the left ventricle.