cardiovascular system

• pulmonary circuit


  carries deoxygenated blood to the lungs and oxygenated blood back to the heart
• systemic circuit


  carries oxygenated blood to the body and deoxygenated blood back to the heart
• left hand side of the heart


  blood is oxygenated at the lungs and brought back to the heart via the pulmonary vein to become deoxygenated
• right hand side of the heart


  deoxygenated blood from the muscles and organs arrive back at the heart via the vena cava before going to the lungs for oxygen
• the conduction system


  Sino-atrial node, atrio-ventricular node, bundle of his, bundle branches, purkinje fibres
• the conduction system


  the SA node fires an electrical impulse causing the atria to contract. The AV node receives these impulses and holds it for 0.1 of a second whilst the atria finishes contracting. The impulse then travels to the bundle of his where it is split into two. The impulse then travels down to the purkinje fibres where the ventricles then contract
• chemoreceptors


  located in muscles and inform the cardiac control centre of chemical changes to the blood stream. Detect an increase in CO2 and a decrease in O2
• proprioreceptors


  located in the muscles and inform the cardiac control centre of motor activity
• baroreceptors


  located in arterial walls and inform the cardiac control centre of change in blood pressure due to stretching of arteries
• cardiac control centre


  a control centre in the medulla oblongata responsible for the regulation of heart rate . during exercise, receptors will send an impulse to the medulla oblongata which sends an impulse through the sympathetic nervous system to the SA node so heart rate increases
• Starlings law of the heart explaining how stroke volume increases during activity


  during exercise there is an increase in venous return, as more blood is returning to the heart there is an increase in stretch of the heart walls. this increase in stretch leads to an increase in contraction strength, therefore more blood is ejected from the left ventricle. this is known as an increased ejection fraction. as more blood is leaving the heart, stroke volume and cardiac output increases.
• when a question mentions systole and diastole phases what is it asking you about


  the conduction system with the AV SA nodes etc
• mechanisms of Venus return


  skeletal muscle pump, respiratory pump, one way pocket valve, venocontriction of smooth muscle in the veins, suction pump of heart
• describe how running effects the venous return mechanism

  skeletal muscle pump increases venous return due to contraction of muscles squeezing blood in veins towards the heart. suction action of heart increases Venus return and due to increased heart rate, more blood is sucked from veins back to the heart. Respiratory pump increases Venus return due to increased inspiration and pressure differences in thoracic and abdominal activity