Cardiovascular System: Heart Anatomy

• CVS is the Cardiovascular System

Cardiovascular System Components

• The cardiovascular system consists of the heart and blood vessels.
• Blood vessels include arteries, veins, and capillaries.

Heart Location and Description

• 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.

Heart Anatomy

• The heart has 4 chambers: 2 atria (right and left) and 2 ventricles (right and left).
• It has 4 borders: upper, lower, right, and left.
• The heart has 4 surfaces: anterior, posterior, right, and left.
• The base of the heart is directed backward, and the apex is directed downward and to the left.

Heart Chambers

• The right atrium receives deoxygenated blood from all body parts via the superior and inferior vena cava.
• The right atrium sends blood to the right ventricle through the tricuspid valve.
• The left atrium receives oxygenated blood from the lungs through 4 pulmonary veins.
• The left atrium pumps blood to the left ventricle via the mitral valve.
• The right ventricle sends deoxygenated blood to the pulmonary artery (via the pulmonary valve), which then divides into two branches for each lung, where oxygenation occurs.
• The two ventricles are separated by the interventricular septum.
• The left ventricle pumps oxygenated blood to the body through the aortic valve, into the aorta and its branches.

Heart Valves and Coverings

• The heart contains 4 valves: tricuspid, pulmonary, mitral, and aortic.
• The heart is covered by the fibrous pericardium and serous pericardium.

Blood Supply to the Heart

• The heart is supplied by 2 arteries: the right coronary and left coronary arteries.
• These arteries branch from the ascending aorta.

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 results in elevated cardiac enzymes, specifically CK and troponin.

Surface Anatomy of the Heart

• Borders of the heart can be outlined on the body's surface using 4 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 the heart) Left 5th intercostal space, 9 cm from the median plane.

Borders based on surface anatomy

• Upper border: lies between points A and B.
• Right border: lies between points B and C.
• Lower border: lies between points C and D.
• Left border: lies between points D and A.

Surface Anatomy of Heart Valves

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

Systemic Circulation

• Begins in the left ventricle where oxygenated blood is pumped through the aorta and its branches.
• Blood reaches all body tissues, where gas and material exchange occurs.
• Deoxygenated blood is collected by small veins, then large veins, and finally enters the right atrium via the superior and inferior vena cava.
• Blood flows from the right atrium to the right ventricle and this completes systemic circulation with a new cycle starting.

Pulmonary Circulation

• Initiates in the right ventricle where venous blood flows through the pulmonary artery and its two branches to the lungs.
• Gas exchange happens in the lungs.
• Oxygenated blood returns to the left atrium via the 4 pulmonary veins, proceeding to the left ventricle, and initiating a new cycle.

Portal Circulation

• Venous blood from the stomach, spleen, pancreas, and intestines is collected into the portal vein.
• The portal vein enters the liver (through the porta hepatis) and divides into branches that end in liver sinusoids.
• Blood exits liver sinusoids through hepatic veins that drain into the inferior vena cava, then to the right atrium.