Cardiovascular System and Heart Anatomy

• The cardiovascular system (CVS) consists of the heart and blood vessels, including arteries, veins, and capillaries.

Anatomy of the Heart

• The heart is a conical muscular pump located behind the sternum and costal cartilages.
• It extends from the 2nd to the 6th costal cartilages.
• Approximately 2/3 of the heart lies to the left, and 1/3 to the right of the median plane.
• The heart contains four chambers: two atria (right and left) and two ventricles (right and left).
• The heart has four borders: upper, lower, right, and left, including four surfaces, anterior, posterior, right, and left, with a base directed backward and an apex directed downward and to the left.

Chambers of the Heart

• The right atrium receives deoxygenated blood from the body through the superior and inferior vena cava and sends it to the right ventricle via the tricuspid valve.
• The left atrium receives oxygenated blood from the lungs through four pulmonary veins and pumps it to the left ventricle via the mitral valve.
• The right ventricle sends deoxygenated blood through the pulmonary valve to the pulmonary artery, which then branches to each lung for oxygenation.
• The two ventricles are separated by the interventricular septum.
• The left ventricle pumps oxygenated blood to the body through the aortic valve to the aorta and its branches.
• The heart has four valves: tricuspid, pulmonary, mitral, and aortic.
• The heart is covered by the fibrous and serous pericardium.

Blood Supply

• The heart is supplied by the right and left coronary arteries.
• The right and left coronary arteries originate from the ascending aorta.

Applied Anatomy: Ischemic Heart Disease

• Narrowing of small coronary artery branches due to atherosclerosis leads to angina pectoris.
• Occlusion of main arteries leads to myocardial infarction (MI).
• Myocardial infarction is characterized by elevated cardiac enzymes like CK and troponin.

Surface Anatomy of the Heart

• Surface anatomy involves drawing organs on the skin.
• The borders of the heart are outlined on the body's surface by four points:
• Point A: left 2nd costal cartilage, 4 cm from the median plane.
• Point B: right 3rd costal cartilage, 3 cm from the median plane.
• Point C: right 6th costal cartilage, 3 cm from the median plane.
• Point D: (apex of heart) left 5th intercostal space, 9 cm from the median plane.
• The upper border is between points A and B.
• The Right border is between points B and C.
• The lower border is between points C and D.
• The left border is between points D and A.

Surface Anatomy of Valves

• Pulmonary valve: behind the left border of the sternum, opposite the 3rd costal cartilage.
• Aortic valve: behind the left border of the sternum, opposite the 3rd intercostal space.
• Mitral valve: behind the left border of the sternum, opposite the 4th costal cartilage.
• Tricuspid valve: behind the body of the sternum, opposite the 4th intercostal space.

Systemic Circulation

• Systemic circulation begins in the left ventricle.
• Oxygenated blood passes through the aorta and its branches to tissues for gas exchange.
• Deoxygenated blood is collected by small veins, then large veins, and finally, the superior and inferior vena cava.
• Blood passes from the right atrium to the right ventricle, completing the cycle.

Pulmonary Circulation

• Pulmonary circulation starts in the right ventricle.
• Venous blood passes through the pulmonary artery and its two branches to the lungs for gas exchange.
• Oxygenated blood returns via four pulmonary veins to the left atrium, then to the left ventricle, where a new cycle occurs.

Portal Circulation

• Portal circulation collects venous blood from the stomach, spleen, pancreas, and intestine.
• Blood enters the liver through the portal vein (porta hepatis), which divides into liver sinusoids.
• Blood leaves the liver sinusoids via hepatic veins, ending in the inferior vena cava and then the right atrium.