The structure of the heart

Describe the general structure of the heart

• It is 2 pumps deoxygenated blood on the right side and oxygenated on the left side.

• Made of cardiac muscle, supplied with oxygen for regular rhythmic contraction by coronary artery

• Pericardial membranes surround heart, they can’ stretch so heart does not over distend with blood

Name each part of the heart

1. Superior vena cava

2. Inferior vena cava

3. Right atrium

4. Tricuspid valve (Right AV valve)

5. Right ventricle

6. Interventricular septum

7. Aorta

8. Left and right pulmonary artery

9. Left atrium

10. Bicuspid valve (Left AV valve)

11. Left ventricle

12. Papillary muscles

13. Pulmonary valve (semilunar)

14. Aortic valve (semilunar)

External view of heart

Why is the left ventricle thicker than the right

This is because the left side pumps blood around body, whereas right ventricle pumps blood to lungs (reduced pressure to prevent rupture of capillaries surrounding alveoli)

Why are the atria thinner walled than ventricles

Atria only have to pump to the ventricles which are nearby whilst ventricles have to pump blood to lungs or rest of body which is a larger distance away.

What are the 3 main layers      

• Epicardium

• Myocardium

• Endocardium

Describe epicardium

Outer layer of the heart wall and thin protective layer

Describe myocardium

• Thick middle layer of cardiac muscle, responsible for contracting and pumping blood.

• Thickest in the left ventricle as that is where blood is pumped to whole body

Describe endocardium

Inner lining of the heart chambers. Thin, smooth layer that reduces friction as blood flows through heart.

How the AV valves work

What is the importance of the septum

It separates deoxygenated blood in the right side from the oxygenated blood in the left side.

A heart murmur is an indication there is a hole in the septum meaning deoxygenated and oxygenated blood will mix reducing oxygen delivery.