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Flow of Blood through the heart Think of the blood flow around the heart‐ lungs‐heart‐body as a one way walk through the hallways and rooms of a house, you are only able to enter each room through one door and leave out through another, then leave the house through a different door – go around the garden then back in the front door again. The heart is made up of 4 chambers or “rooms”. 2 rooms on the left side of the heart, 2 rooms on the right (as if you were looking at a person, their left, their right.) The left and right side of the heart are separated by the septum (central wall) keeping oxygenated and deoxygenated blood separate. The pathway through the rooms or chambers is controlled by a one way valve system (or doorways) into the next chamber and blood vessels (think corridors/hallways). Deoxygenated blood enters the Right Atrium (first room) by the vena cavae (main hallway) During the relaxation phase of the heart beat (diastole) the right atria fills and blood passes through the Tricuspid valve (one way doorway) into the right ventricle (next room) and the Tricuspid valve closes behind it (automatic door) The Right ventricle contracts (systolic phase) pushing the blood through the Pulmonary valve (next doorway) up the pulmonary artery (corridor) to the lungs. (Imagine this is like a sealed corridor out to an outbuilding –ie lungs. It is not possible to re‐enter any of the previous rooms or chambers again). Once in the lungs the blood is oxygenated and C02 is removed. Blood then resumes its journey to the left atrium via the pulmonary vein (main hallway back to the main house) During the relaxation phase of the heart beat (diastole) the left atria fills and blood passes through the Mitral valve (one way doorway) into the left ventricle (next room) and the mitral valve closes behind it (automatic door) The left ventricle contracts (systolic phase) pushing the blood through the Aortic valve (next door) up the Aorta (main corridor) out through the main arteries to the body. The Left ventricle has more muscular walls as it has to pump blood all around the body. The right ventricle has less muscular walls as it is only pumping blood to the lungs. Linda Bracken DEHF Additional notes for NCEF CEHF students Simple diagram of heart – suggest draw as if plan of a house. the Lungs exchange of gases To the body
Left Atrium Mitral valve
Aortic valve Left ventricle Right Ventricle
Pulmonary valve Tricuspid valve Right Atrium Pulmonary artery S
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Aorta Vena cavae Pulmonary vein
Deoxygenated blood Oxygenated blood Valves Linda Bracken DEHF Additional notes for NCEF CEHF students