Heart

• Right ventricle: pumps blood to lungs, less muscle
• Right atrium: vena cava brings blood from body
• Left ventricle: pumps blood to the rest of the body, more muscle
• Left atrium: pulmonary vein brings blood from lungs
• Aorta: connected to left ventricle, carries oxygenated blood to the rest of the body
• Vena cava: connected to the right atrium, brings deoxygenated blood from tissues of the body
• Pulmonary artery; connected to right ventricle, carries deoxygenated blood to the lungs
• Pulmonary vein: connected to left atrium, carries oxygenated blood from lungs
• Coronary artery: the heart muscles own blood vessel
• Cardiac cycle

  -beating of the two sides is synchronised

  -when the left side contracts so does the right side

  -right side only pumps to the lungs

  -wall of left ventricle is thicker than the right, and produces more pressure

  -3 main stages: artial systole, ventricular systole and diastole
• Diastole:

  -walls of atria and ventricles relax

  -pressure drops rapidly

  -arterial blood pressure is now higher, this forces semi-lunar valves to shut

  -blood is unable to flow

  -blood flows from veins into atrium
• Atrial systole:

  -walls of atria contract

  -blood passes from atrioventricular valves to ventricles

  -atrial walls are thin (don’t produce much pressure)

  -takes approx 0.1 secs
• Ventricular systole:

  -thick muscle walls of ventricles contract

  -blood in ventricles squeezed and pressure rises

  -when pressure of blood in ventricles is more than the pressure in atria, the flaps of the AV valve are pushed shut, preventing back flow

  -SV valves open

  -blood flows out of right ventricle into pulmonary artery and out of left ventricle into atria

  -lasts approx 0.3 secs