Overview
This lesson explains the flow of blood through the heart, including the main heart structures, valves, and blood vessels, and the sequence of blood movement.
Basic Concepts & Structures
- The heart is the central organ of the circulatory system, moving blood to supply oxygen and nutrients.
- Veins carry blood toward the heart; arteries carry blood away from the heart.
- Deoxygenated blood is shown as blue; oxygenated blood is shown as red.
- The heart contains four chambers: right atrium, right ventricle, left atrium, and left ventricle.
- The atria (upper chambers) help fill the ventricles (lower chambers) before ventricular contraction.
- The right side of the heart handles deoxygenated blood; the left side handles oxygenated blood.
- Four main valves control blood flow: tricuspid (right atrium exit), pulmonic (right ventricle exit), mitral/bicuspid (left atrium exit), and aortic (left ventricle exit).
Blood Flow Through the Heart
- Deoxygenated blood returns to the heart through the inferior and superior vena cava into the right atrium.
- Right atrium contracts, sending blood through the tricuspid valve into the right ventricle.
- Right ventricle contracts, pushing blood through the pulmonic valve into the pulmonary artery.
- Pulmonary artery transports deoxygenated blood to the lungs for oxygenation.
- Oxygenated blood returns from the lungs via the pulmonary veins into the left atrium.
- Left atrium contracts, moving blood through the mitral valve into the left ventricle.
- Left ventricle contracts, ejecting blood through the aortic valve into the aorta and then to the body.
Key Structures & Vessels
- Inferior vena cava: returns deoxygenated blood from the lower body.
- Superior vena cava: returns deoxygenated blood from the upper body.
- Pulmonary artery: carries deoxygenated blood from the heart to the lungs.
- Pulmonary veins: return oxygenated blood from the lungs to the heart.
- Aorta: carries oxygenated blood from the heart to the body.
Memory Aids
- Valve order mnemonic: TPMA (Tricuspid, Pulmonic, Mitral, Aortic) — "Toilet Paper My Asset".
Key Terms & Definitions
- Atrium — upper heart chamber that receives blood.
- Ventricle — lower heart chamber that pumps blood out of the heart.
- Vein — blood vessel carrying blood toward the heart.
- Artery — blood vessel carrying blood away from the heart.
- Tricuspid Valve — valve between right atrium and right ventricle.
- Pulmonic Valve — valve between right ventricle and pulmonary artery.
- Mitral (Bicuspid) Valve — valve between left atrium and left ventricle.
- Aortic Valve — valve between left ventricle and aorta.
Action Items / Next Steps
- Memorize the blood flow sequence and valve order using the TPMA mnemonic.
- Review associated diagrams of heart chambers and vessels.