2.65: Describe the Structure of Arteries, Veins and Capillaries and Understand their Roles

STRUCTURE

ARTERIES Carries Oxygenated Blood Away from the Heart (Excluding Pulmonary Artery) Has Thick Muscular Walls (To Withstand High Pressure) Has Small Lumen (Passageways) Blood is Under High Pressure to Pump Blood to the Whole Body

VEINS Carries Deoxygenated Blood to the Heart (Excluding the Pulmonary Vein) Has Thin Walls Has Large Lumen (Passageways) Has Valves to Prevent the Backflow of Blood as it is Under Low Pressure Blood is under Low Pressure

CAPILLARIES Where Gas Exchange Takes Place; Oxygen Diffuses through the Capillary Walls and Into the Tissues for Aerobic Respiration, Carbon Dioxide Diffuses Out of the Tissue into the Blood Found in Muscles of Lungs Thin Cell Walls (One cell Thick) so Distance of Diffusion is Short, Efficient Rate of Diffusion Low Blood Pressure Blood Will Travel Through the Capillaries and is Where Exchange of Gases and Substances Commonly Take Place