Structure
Vessels of the Heart

  • The vessels which supply the heart with oxygenated blood are called the coronary arteries
  • In the Vena cava, blood is deoxygenated after it has circulated the body and travels into the right atrium
  • The pulmonary artery has deoxygenated blood in it which travels from the right ventricle to the lungs
  • The left atrium has oxygenated blood straight from the pulmonary vein
  • The blood travels from:

Vena cava -> Pulmonary Artery -> Pulmonary Vein -> Aorta

  • Deoxygenated and oxygenated blood should not mix as they have varying concentrations of oxygen in them. If oxygenated blood reaches the lung it will reduce the concentration gradient, therefore less oxygen is absorbed.

Chambers of the Heart

  • The heart is made up of 4 chambers, the left and right atrium and the left and right ventricles
  • Blood enters the right atrium through the superior and inferior vena cava during diastole.
  • In atrial systole, the atria contract to push the blood down into the right ventricle
  • In ventricular systole, the blood is pushed out of the right ventricle into the pulmonary artery which leads to the lungs for the blood to be deoxygenated. The blood then returns through the pulmonary veins back into the left atrium of the heart
  • During diastole, the blood flows from the left atrium down into the left ventricle
  • In ventricular systole, the blood is then pushed out of the left ventricle through the aorta and out to the rest of the body

Coronary Arteries and veins

  • Coronary arteries leave from the aorta into the heart muscle tissues via capillaries before leaving via the coronary veins
  • If one of the arteries gets blocked, then the heart tissue is starved of oxygen. Cardiac tissue is unable to respire anaerobically and therefore will die. Resulting in a heart attack.

Heart Valves

  • Semi-lunar valves link the ventricles to the pulmonary artery (pulmonary valve) and the aorta (aortic valve) . They prevent blood from re-entering the heart after the ventricular systole
  • Atrioventricular valves (tricuspid on the right, bicuspid (mitral) on the left) like the atria to the ventricles. They prevent blood from being pushes back into the atria after ventricular systole