Anatomy of the Heart
Let's dive into the fascinating structure of our body's most important pump - the heart! Understanding its anatomy is crucial for grasping how our cardiovascular system functions during exercise and rest.
Heart Chambers
The heart consists of four main chambers:
- Right Atrium (RA)
- Upper right chamber
- Receives deoxygenated blood from the body via the superior and inferior vena cava
- Acts as a collection chamber
- Right Ventricle (RV)
- Lower right chamber
- Pumps deoxygenated blood to the lungs
- Has thinner walls compared to the left ventricle
- Left Atrium (LA)
- Upper left chamber
- Receives oxygenated blood from the lungs via pulmonary veins
- Slightly thicker walls than the right atrium
- Left Ventricle (LV)
- Lower left chamber
- Thickest walls of all chambers
- Pumps oxygenated blood to the entire body
The left ventricle has the thickest walls because it needs to generate enough pressure to pump blood throughout the entire body.
Heart Valves
The heart has four main valves that ensure one-way blood flow:
- Tricuspid Valve
- Located between right atrium and right ventricle
- Has three cusps (flaps)
- Pulmonary Valve
- Between right ventricle and pulmonary artery
- Also called pulmonic valve
- Mitral Valve
- Between left atrium and left ventricle
- Has two cusps
- Also called bicuspid valve
- Aortic Valve
- Between left ventricle and aorta
- Prevents backflow into the left ventricle
Remember the flow direction: "AV valves" (Tricuspid and Mitral) prevent backflow from ventricles to atria, while "Semilunar valves" (Pulmonary and Aortic) prevent backflow from arteries to ventricles.
Major Blood Vessels
The heart connects to several major blood vessels:
- Veins bringing blood TO the heart:
- Superior Vena Cava (from upper body)
- Inferior Vena Cava (from lower body)
- Pulmonary Veins (from lungs)
- Arteries carrying blood AWAY from the heart:
- Pulmonary Artery (to lungs)
- Aorta (to body)
Students often confuse pulmonary arteries and veins. Remember: Pulmonary arteries carry deoxygenated blood, while pulmonary veins carry oxygenated blood - opposite to the general rule for arteries and veins!
ExampleBlood Flow Path Through the Heart:
- Deoxygenated blood → Right Atrium
- Through Tricuspid Valve → Right Ventricle
- Through Pulmonary Valve → Pulmonary Artery → Lungs
- Oxygenated blood returns via Pulmonary Veins → Left Atrium
- Through Mitral Valve → Left Ventricle
- Through Aortic Valve → Aorta → Body
