Overview
This lecture covers the anatomy of the heart, focusing on its dual-pump structure, the flow of blood, the major vessels, the valves, and the systemic and pulmonary circuits.
Structure of the Heart
- The heart functions as two separate pumps: right and left sides.
- Each pump has similar anatomical flow: atria → atrioventricular (AV) valve → ventricle → semilunar valve → major vessel.
- The atria are the smaller, upper chambers; ventricles are the larger, lower chambers.
Heart Valves and Blood Flow
- AV valves separate the atria from the ventricles (right: tricuspid; left: bicuspid/mitral).
- Semilunar valves control flow from the ventricles to arteries (pulmonary and aortic valves).
- Chordae tendineae and papillary muscles prevent valve inversion and backflow.
- Heart valves ensure one-way blood flow and prevent backflow into chambers.
Circuits of Blood Flow
- The right side (pulmonary circuit) receives deoxygenated blood and sends it to the lungs.
- The left side (systemic circuit) receives oxygenated blood from the lungs and pumps it to the body.
- “Blue” in diagrams represents oxygen-poor blood; “red” is oxygen-rich blood (but blood is always some shade of red).
Major Vessels and Coronary Circulation
- Superior vena cava returns blood from the upper body; inferior vena cava from the lower body.
- The coronary sinus drains deoxygenated blood from the heart muscle into the right atrium.
- Pulmonary trunk branches into left and right pulmonary arteries, which carry blood to the lungs.
- Pulmonary veins return oxygenated blood to the left atrium.
- Aorta distributes oxygenated blood throughout the body.
Anatomy and Blood Flow Path
- Blood flow: body → vena cavas/coronary sinus → right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary trunk/arteries → lungs → pulmonary veins → left atrium → bicuspid/mitral valve → left ventricle → aortic valve → aorta → body.
- The left ventricular myocardium is thicker due to the higher force needed to circulate blood systemically.
Arteries, Veins, and Branches
- Arteries carry blood away from the heart; veins carry blood toward the heart.
- The aortic arch branches into the brachiocephalic, carotid, and subclavian arteries (“BCS”).
- Above the diaphragm: thoracic aorta; below: abdominal aorta.
- Blood vessels change names as they branch or move to different body regions.
- Venules are small veins located between capillaries and larger veins.
Key Terms & Definitions
- Atria — upper heart chambers receiving blood.
- Ventricle — lower, muscular heart chambers pumping blood out.
- AV Valve — separates atria and ventricles (tricuspid on right, bicuspid/mitral on left).
- Semilunar Valve — valve at the exit of each ventricle (pulmonary and aortic).
- Chordae Tendineae — tendon-like cords anchoring heart valves.
- Papillary Muscle — finger-like muscle projections attaching to chordae tendineae.
- Pulmonary Circuit — right heart/lungs circuit for oxygenation.
- Systemic Circuit — left heart/body circuit delivering oxygenated blood.
- Coronary Sinus — vein collecting deoxygenated blood from heart tissue.
- Venules — small veins collecting blood from capillaries.
Action Items / Next Steps
- Review heart anatomy diagrams and practice tracing the path of blood through the heart.
- Familiarize yourself with the names and locations of the major vessels and valves.
- Prepare for upcoming laboratory work involving heart dissection and identification of structures.