The Circulatory System

The Circulatory System

1. Blood Flow

   • Vena Cava
     • Right Atrium
       • Right Ventricle
         • 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
   • Red = oxygentated blood
   • Blue = deoxygenated blood
   • Purple = diffusion of oxygen

2. Blood Vessels

   • Arteries
     • Narrow lumen
       • Maintains high pressure
     • Thicker Walls
       • To be able to cope with higher pressure
     • More collagen
       • Collagen is a tough, fibrous protein in the arterial walls that makes them strong & durable
     • Smooth Muscle Cells
       • Allow them to constrict & dilate
     • Elastic Fibres
       • Allow it to stretch & recoil
     • No Valves
       • The blood is of a high pressure and constantly being pushed forwards, so there is no need to use valves to prevent backflow
   • Veins
     • Wide Lumen
       • This allows more blood flow at the lower pressure of the veins
     • Thinner Walls
       • There is a lower pressure
     • Less Collagen
       • They are under lower pressure
     • Less Smooth Muscle Cells
       • The veins do not need to be able to stretch and recoil as much
     • Fewer Elastic Fibres
       • They are under low pressure so require less elastic fibres
     • Valves
       • Prevent backflow due to low pressure
   • Capillaries
     • Found in muscles & lungs
       • Supply oxygen
       • Take away Carbon Dioxide
     • Thin walls - 1 cell thick
       • Access to every cell in the body
     • Very low blood pressure
       • The thin walls can't cope with higher pressure
     • Gas exchange occurs here
       • Supply substances to every cell in the body

3. Labelled Heart Diagram

   • The aorta is an artery that carries oxygenated blood around the body
     • The pulmonary artery carries deoxygenated blood to the lungs
       • The left atrium contracts to pump oxygenated blood into the left ventricle
         • 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

Images and files in the map