| Feature | Arteries | Veins |
|---|---|---|
| Direction | Away from the heart | Toward the heart |
| Wall Structure | Thick, muscular, and elastic | Thin, less muscular, wider lumen |
| Pressure | High pressure | Low pressure |
| Valves | Absent (except at heart exit) | Present to prevent backflow |
| Oxygenation | Usually oxygenated (except Pulmonary) | Usually deoxygenated (except Pulmonary) |
The 'Pulmonary Exception': Always remember that the Pulmonary Artery is the only artery carrying deoxygenated blood, and the Pulmonary Vein is the only vein carrying oxygenated blood. Examiners frequently test this reversal of the standard rule.
Valve Nomenclature: Use the mnemonic 'LAB RAT' to remember valve locations: Left Atrium Bicuspid, Right Atrium Tricuspid.
Pressure-Velocity Relationship: Note that while pressure is highest in the aorta, the velocity of blood is lowest in the capillaries. This is a common point of confusion; velocity depends on total cross-sectional area, not just distance from the heart.
Wall Thickness Logic: If asked to identify a heart chamber on a diagram, look for the thickest wall; that is always the Left Ventricle.
Blue Blood Myth: A common misconception is that deoxygenated blood is actually blue. In reality, it is dark red; it only appears blue through the skin due to light scattering and the properties of the vessel walls.
Artery = Oxygenated?: Students often define arteries by oxygen content. This is incorrect. Arteries are defined strictly by the direction of flow (away from the heart).
Atria vs. Ventricles: Do not confuse the roles; atria are 'receivers' with thin walls, while ventricles are 'pumps' with thick walls.
