Cardiology – The Basics
1. Anatomy of the Heart
● Location: Mediastinum, between the lungs, behind the sternum, apex points down and
to the left.
● Layers:
1. Endocardium – inner lining
2. Myocardium – muscular middle layer (contracts)
3. Epicardium / Pericardium – outer layer, pericardial sac protects and reduces
friction
● Chambers:
1. Right atrium (RA): receives deoxygenated blood from the body (via superior &
inferior vena cava)
2. Right ventricle (RV): pumps blood to the lungs via pulmonary artery
3. Left atrium (LA): receives oxygenated blood from lungs via pulmonary veins
4. Left ventricle (LV): pumps oxygenated blood to the body via aorta
● Valves:
1. Atrioventricular (AV) valves: tricuspid (right), mitral/bicuspid (left)
2. Semilunar valves: pulmonary (RV→lungs), aortic (LV→body)
● Coronary arteries: supply the heart muscle itself (LAD, RCA, circumflex)
2. Physiology – How the Heart Works
1. Blood Flow Path:
Body → RA → tricuspid → RV → pulmonary valve → lungs → LA → mitral → LV →
aortic valve → body
2. Electrical Conduction System:
○ SA node (sinoatrial): pacemaker, generates impulse (~60–100 bpm)
○ AV node: slows impulse
○ Bundle of His → Purkinje fibers: ventricles contract
3. Heart Sounds:
○ S1: “lub” – AV valves close (ventricular contraction)
○ S2: “dub” – semilunar valves close (ventricular relaxation)
○ S3 / S4: abnormal in adults, may indicate heart failure or stiff ventricles
4. Cardiac Cycle:
○ Systole: ventricles contract, blood pumped out
○ Diastole: ventricles relax, chambers fill
3. Common Cardiovascular Diseases
1. Hypertension (HTN):
○ High blood pressure (>130/80 mmHg)
○ Can lead to heart failure, stroke, kidney damage
2. Coronary Artery Disease (CAD):
○ Narrowing of coronary arteries → decreased blood flow to heart
1. Anatomy of the Heart
● Location: Mediastinum, between the lungs, behind the sternum, apex points down and
to the left.
● Layers:
1. Endocardium – inner lining
2. Myocardium – muscular middle layer (contracts)
3. Epicardium / Pericardium – outer layer, pericardial sac protects and reduces
friction
● Chambers:
1. Right atrium (RA): receives deoxygenated blood from the body (via superior &
inferior vena cava)
2. Right ventricle (RV): pumps blood to the lungs via pulmonary artery
3. Left atrium (LA): receives oxygenated blood from lungs via pulmonary veins
4. Left ventricle (LV): pumps oxygenated blood to the body via aorta
● Valves:
1. Atrioventricular (AV) valves: tricuspid (right), mitral/bicuspid (left)
2. Semilunar valves: pulmonary (RV→lungs), aortic (LV→body)
● Coronary arteries: supply the heart muscle itself (LAD, RCA, circumflex)
2. Physiology – How the Heart Works
1. Blood Flow Path:
Body → RA → tricuspid → RV → pulmonary valve → lungs → LA → mitral → LV →
aortic valve → body
2. Electrical Conduction System:
○ SA node (sinoatrial): pacemaker, generates impulse (~60–100 bpm)
○ AV node: slows impulse
○ Bundle of His → Purkinje fibers: ventricles contract
3. Heart Sounds:
○ S1: “lub” – AV valves close (ventricular contraction)
○ S2: “dub” – semilunar valves close (ventricular relaxation)
○ S3 / S4: abnormal in adults, may indicate heart failure or stiff ventricles
4. Cardiac Cycle:
○ Systole: ventricles contract, blood pumped out
○ Diastole: ventricles relax, chambers fill
3. Common Cardiovascular Diseases
1. Hypertension (HTN):
○ High blood pressure (>130/80 mmHg)
○ Can lead to heart failure, stroke, kidney damage
2. Coronary Artery Disease (CAD):
○ Narrowing of coronary arteries → decreased blood flow to heart
