09 May 2013

# 70 Structure and function of the heart

The function of the heart is to pump blood around the body. The right side pumps blood to the lungs and the left side pumps blood to the rest of the body

Heart's function

  • Blood circulation 
  1. Blood in the right ventricle (RV) is pump to the lungs 
  2. Blood from the lungs flows back into the left atrium (LA) and then into the left ventricle (LV).
  3. Blood in the LV is pumped through the body (except for the lungs)
  4. Blood returns to the heart where it enters the right atrium (RA). 
  • Muscular contraction
The heart is made of a special type of muscle called cardiac muscle which contracts and relaxes regularly, throughout life.

The heart’s muscle is constantly active, so it needs its own blood supply, through the coronary artery, to provide it with oxygen and glucose

  • Working of the valves 
Valves in the heart prevent blood from being pushed backwards up into the atria when the heart ‘beats’. 


Try this 

1.On a copy of the diagram of the double circulatory system, labell:
i)            The 4 main blood vessels (4 marks)
ii)           The chambers of the heart (4 marks)
iii)         The 2 valves shown (2 marks)

2.State 2 differences in composition between blood leaving the right ventricle and blood entering the left atrium. (2 marks)


2.Blood leaving the right ventricle has more CO2 and less O2 than blood entering the left atrium. 

Common misconceptions

Remember that blood passing through the chambers of the heart does not supply the heart muscle with oxygen or glucose. The heart muscles has its own blood supply - via the coronary arteries - to do this. 


  1. The tricuspid valve and bicuspid valves are in the wrong spot. The tricuspid valve is situated in between the left atrium and ventricle and the bicuspid valve is situated in between the right atrium and ventricle. In your diagram they are flipped.

  2. Actually, the bicuspid valve is not even labeled. The tricuspid valve is labeled, but in the wrong spot.

  3. The bicuspid valve (the mitral valve or left atrioventricular valve) is between the left atrium and the left ventricle.
    The tricuspid valve, or right atrioventricular valve, is between the right atrium and the right ventricle.
    I've checked all diagrams, both vavles are correctly labeled.