BY2 - Transport In Animals

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  • Transport in Animals (2)
    • Heart Structure
      • Right Hand Side
        • Carries deoxygenated blood.
        • Right atrium
          • Right ventricle
        • Pulmonary artery
          • Takes blood to the lungs.
        • Vena cava
          • Veins which bring blood to the heart.
        • Atrio-ventrixular valve
          • Tricuspid
      • Left Hand Side
        • Carries oxygenated blood.
        • Pulmonary vein
          • Brings blood from the lungs to the heart.
        • Aorta
        • Atrio-ventricular valve
          • Bicuspid
        • Left ventricle
          • Left atrium
      • Septum is the separating wall between the left and right sides.
        • Prevents blood flowing from one side of the heart to the other.
      • Heart is made of cardiac muscle.
        • Specialised tissue
        • Capable of rhythmic contraction and relaxation of its own accord.
          • MYOGENIC
        • Has its own blood vessels.
          • Coronary vessels
          • Supply oxygen to the heart.
      • Valves are connected by tendons
    • Cardiac Cycle
      • 1. Atrial Systole
        • Muscle wall of the atria contracts
          • This forces blood through the open atrio-ventricular valves (bicuspid and tricuspid) and into the ventricles.
            • Blood cannot flow backwards.
              • This is because of a greater pressure in front of the valves that forces them to close.
        • Systole = Contract
          • Contractions create pressure.
      • 2. Ventricular Systole
        • Atria relaxes.
        • Muscles in the wall of the left and right ventricles contract.
          • Blood moves from the ventricles through the semi-lunar valves.
            • This forces the valves to open.
              • High pressure behind the valves causes them to open.
            • Blood flows out and into the pulmonary artery and aorta.
              • Tricuspid and bicuspid (atrio-ventricular valves) close because of the rise in pressure in the ventricles.
        • The ventricles contain more muscle than the atria so they generate more pressure to force the blood a greater distance.
      • Ventricular Diastole
        • Muscles in the wall of the atria and ventricles relax.
          • Pressure inside the ventricles falls and the volume (space) increases.
            • Blood would flow back into the aorta and pulmonary artery but the semi-lunar valves are forced shut because there is a high pressure in front of the valves.
        • During diastole the elastic rebound of the aorta helps to maintain arterial pressure.
        • Diastole = Relax
      • Blood from the vena cava and pulmonary vein enters the atria and the cycle starts over.
      • The left ventricle has a thicker muscle than the right ventricle.
        • It has to pump the blood all around the body while the right ventricle only has to pump it to the lungs.
      • Atrial Systole
        • High atrial pressure
        • Low ventricular pressure
        • Atrio-ventricular valves open
        • Semi-lunar valves close.
        • Ventricular Systole
      • Diastole
        • Low atrial pressure
        • Low ventricular pressure
        • Atrio-ventricular valves open
        • Semi-lunar valves close
    • How is the cardiac cycle initiated and controlled?
      • Atrio-ventricular Node
        • Receives impulses from the Sino-Atrial Node and passes the impulses onto the Purkyne Fibres.
          • Allows for a delay which stops the atria and ventricles from contracting at the same time.
        • Purkyne Fibres pass the impulse to the apex.
          • Apex = Bottom of the heart
      • Purkyne Fibres / Bundle Of His
        • Conducts the impulses to the ventricles and ensures the heart contracts from the apex up.
          • This forces the atrial walls to contract up from the apex and pumps blood into the aorta.
      • Sino-Atrial Node
        • Generates electrical impulses
          • They cannot pass to the ventricles on their own
          • Causes the atrial muscles to contract
        • Initiates impulses
        • Specialised cardiac fibres
          • Acts as a pacemaker
            • Sets the pace of the cardiac cycle
      • What can change the cycle?
        • Adrenaline
          • Increases heartbeat
        • Exercise
          • Increases heartbeat

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