B3- transporting materials

circulatory system and the heart

• large organisms need a transport system (blood,heart and blood vessles) to move materials around the body
• heart is the muscular organ thatt does this
• the right pump deoxygenates
• and the left pump oxygenates
• the heart has 4 chambers
• 1. blood high in c02 enters the right side via the vena cava, it flows into right atrium through the right ventricle and is carried by the pulmonary artery to the lungs
• 2. the pulmonary vein brings the oxygenated blood from the lungs through the left atrium down the left ventricle and the aorta carries the blood round the body
• the two sides working as one is called double circulation
• valves in the heart prevent back flow of blood

keeping blood flowing

• three types of vessle
• artery- carries blood away from heart and have thick walls with elastic tissue
• vein-thinner walls than an artery with valves to prevent back flow
• capillaries are thin walled vessles to allow exchange of substances with cells in the body
• if vessles become blocked the organs will become oxygen deprived and shut down
• …