Cardiovascular System PDF

The largest vein is the vena cava Arterioles Narrow arteries that branch off the end of the artery and carry blood to the capillaries Venules...

The largest vein is the vena cava Arterioles Narrow arteries that branch off the end of the artery and carry blood to the capillaries Venules Small blood vessels that collect blood from the capillary and carry it to the larger vein for transport back to the heart Capillaries Capillaries are networks of tiny blood vessels which connect the arterioles to the venules They have very thin walls They carry nutrients & oxygen to the tissues and bring back waste products from the tissues Coronary Circulation The heart is supplied by 2 coronary arteries arising from the ascending aorta. Both run in the sulcus Cardiovascular System 11  Right Coronary Artery It is smaller than the left coronary artery It arises from the anterior aortic sinus of ascending aorta It emerges on the surface of the heart between the root of the pulmonary trunk and the right auricle Then it runs through the anterior coronary sulcus, winds round the inferior border and reaches the posterior coronary sulcus to reach the posterior interventricular sulcus as the posterior interventricular branch It terminates by anastomosing with the circumflex branch of the left coronary artery at the crux Area of Supply of the Right Coronary Artery Right Atrium Greater Part of the Right Ventricle Smaller Part of the Left Ventricle Posterior Part of the Interventricular Septum Conducting Systems except left branch of AV bundle Left Coronary Artery It is larger than the right coronary artery It arises from the posterior aortic sinus of ascending aorta It emerges on the surface between the pulmonary trunk & the left auricle It gives out the anterior interventricular branch which passes through the anterior interventricular sulcus and continues as the circumflex artery After giving out the anterior interventricular branch the artery runs to the left in the left anterior coronary sulcus It winds round the left border of the heart & continues in the left posterior coronary sulcus, near the posterior interventricular groove, it terminates by anastomosing with the right coronary artery Area of Supply of Left Coronary Artery Cardiovascular System 12  Left Atrium Greater Part of Left Ventricle Smaller Part of Right Ventricle Anterior Part of Interventricular Septum Part of left branch of AV bundle Coronary Collaterals Cross-connections between coronary arteries, which are present regardless of coronary artery disease (CAD) As natural bypasses, coronary collaterals provide an alternative source of blood flow to a myocardial area when normal supply is compromised Collateral Circulation The coronary arteries anastomose with the following Vasa vasorum of aorta Vasa vasorum of pulmonary arteries Internal thoracic arteries Bronchial Arteries Pericardiophrenic Arteries The last 3 anastomose through the pericardium. These channels may open up in emergencies when both coronary arteries are obstructed. Cardiovascular System 13  Venous Supply of The Heart Coronary sinus is the largest vein of the heart, it is situated in the left posterior coronary sulcus. The following veins drain into the coronary sinus which opens into the right atrium Great cardiac vein Middle cardiac vein Posterior vein of left ventricle Oblique vein of left atrium Right marginal vein The following 2 veins open directly into the right atrium Anterior Cardiac Veins Vanae Cordis Minimae Clinical Significance Arthrosclerosis is the accumulation of the fats, cholesterol and other substances along the walls of the coronary arteries Thrombosis of coronary artery is a common cause of myocardial infarction Incomplete obstruction due to spasm of coronary artery causes angina pectoris Coronary angiography determines the site of narrowing/ occlusion of the coronary arteries Coronary angioplasty helps in removal of blockage Cardiovascular System 14