The Circulatory System

Blood Flow
1. Vena Cava
  1. Right Atrium
    1. Right Ventricle
      1. Pulmonary Artery
        Lungs
        Pulmonary Vein
        Left Atrium
        Left Ventricle
        Aorta
        Rest of the Body
        Vena Cava
        This is the only vein to have oxygenated blood
        This is the only artery to have deoxygenated blood
2. Red = oxygentated blood
3. Blue = deoxygenated blood
4. Purple = diffusion of oxygen
Blood Vessels
1. Arteries
  1. Narrow lumen
    1. Maintains high pressure
  2. Thicker Walls
    1. To be able to cope with higher pressure
  3. More collagen
    1. Collagen is a tough, fibrous protein in the arterial walls that makes them strong & durable
  4. Smooth Muscle Cells
    1. Allow them to constrict & dilate
  5. Elastic Fibres
    1. Allow it to stretch & recoil
  6. No Valves
    1. The blood is of a high pressure and constantly being pushed forwards, so there is no need to use valves to prevent backflow
2. Veins
  1. Wide Lumen
    1. This allows more blood flow at the lower pressure of the veins
  2. Thinner Walls
    1. There is a lower pressure
  3. Less Collagen
    1. They are under lower pressure
  4. Less Smooth Muscle Cells
    1. The veins do not need to be able to stretch and recoil as much
  5. Fewer Elastic Fibres
    1. They are under low pressure so require less elastic fibres
  6. Valves
    1. Prevent backflow due to low pressure
3. Capillaries
  1. Found in muscles & lungs
    1. Supply oxygen
    2. Take away Carbon Dioxide
  2. Thin walls - 1 cell thick
    1. Access to every cell in the body
  3. Very low blood pressure
    1. The thin walls can't cope with higher pressure
  4. Gas exchange occurs here
    1. Supply substances to every cell in the body
Labelled Heart Diagram
1. The aorta is an artery that carries oxygenated blood around the body
  1. The pulmonary artery carries deoxygenated blood to the lungs
    1. The left atrium contracts to pump oxygenated blood into the left ventricle
      1. The pulmonary vein carries oxygenated blood into the left atrium
        The semi-lunar valves stop backflow of blood from the aorta and pulmonary artery back into the ventricles
        The left ventricle contracts to pump oxygenated blood into the aorta
        The heart wall has 3 layers:
        Epicardium
        External layer
        Attached to pericardium (membrane surrounding heart)
        Thin & transparent
        Made of delicate connective tissue
        Mycocardium
        Middle layer
        Responsible for pumping action
        Made out of cardiac muscle
        Endocardium
        Inner layer
        Thin layer endothelium
        Provide smooth lining for chambers & covers valves
        The right ventricle contracts to pump deoxygenated blood into the pulmonary atrtery
        The atrioventricular valves (tricuspid/bicuspid) prevent backflow of bloof back into the atria
        The inferior vena cava is a vein that carries deoxygenated blood from the lower region of the body to the right atrium
        The right atrium contracts to pump deoxygenated blood into the right ventricle
        The superior vena cava is a vein that carries blood from the top region of the body to the right atrium

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The Circulatory System

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	Created by Hannah Vernon-Browne about 9 years ago