Cardiovascular Circulation

• Path of Circulation


  superior/inferior vena cava -- RA -- tricupsid valve

  -- RV -- pulmonary SL valve -- pulmonary trunk, pulmonary arteries

  -- lungs -- pulmonary veins -- LA -- mitral valve -- LV

  -- aortic SL valve -- aorta -- body -- heart
• Pressure Differences Between Ventricles

  equal vols of blood r pumped to the pulmonary + systemic circuits at any moment, but the 2 ventricles have v unequal workloads

  the pulmonary circuit, served by the RV, is a short, low-pressure circulation

  the systemic circuit, LV, takes a long pathway thru the entire body + encounters about 5x as much resistance to blood flow
• Functional Difference Between Ventricles

  the walls of the left ventricle r 3x thicker than those of the RV

  right ventricular cavit is flattened that partially encloses the left ventricle

  = left ventricle can generate much more pressure than the right + is a far more powerful pump
• Coronary Arteries


  the left + right coronary arteries both arise from the base of the aorta + encircle the heart in the coronary sulcus

  they provide the arterial supply of the coronary circulation
• Left Coronary Artery


  the left coronary artery run toward the left side of the heart + then divides into 2 major branches:

  anterior interventricular + circumflex arteries
• Left Coronary Artery - Anterior Interventricular Artery

  follows the anterior interventicular sulcus + supplies blood to the interventricular septum + anterior walls of both ventricles

  
• Left Coronary Artery - Circumflex Artery

  the circumflex artery supplies the left atrium + the posterior walls of the left ventricle
• Right Coronary Artery


  the right coronary artery courses to the right side of the heart where it also gives rise to two branches:

  right marginal artery

  posterior interventricular artery
• Right Coronay Artery - Right Marginal Artery

  right marginal artery serves the myocardium of the lateral right side of the heart

  
• Right Coronary Artery - Posterior Interventricular Artery

  the posterior interventricular artery runs to the heart apex

  + supplies the posterior ventricular walls

  near the apex of the heart, this artery merges w the anterior interventricular artery

  
• Anastomoses


  there r many anastomoses (junctions) among the coronary arterial branches

  these fusing networks provide additional (collateral) routes for blood delivery to the heart muscle, but r not robust enough to supply adequate nutrition when a coronary artery is suddenly occluded

  complete bockage leads to tissue death + heart attack
• Effectiveness of Coronary Arteries

  the coronary arteries provide an intermittent, pulsating blood flow to the myocardium

  these vessels + their main branches lie in the epicardium + send braches inward to nourish the myocardium
• Innefectiveness of Cornary Arteries

  they delvier blood when the heart isrelaxes, but r fairly ineffective when the ventricles r contracting cos they r compressed by the contracting to form an enlarged vessel = cornary sinus

  = empties the blood into the RA
• Coronary Sinus


  the coronary sinus is located on the posterior aspect of the heart

  the sinus has 3 large tributaries:

  great cardiac vein in the anterior interventricular sulcus

  middle cardiac vein in posterior interventricular sulcus

  small cardiac vein running along the heart's right inferior margin