Page 198 - Big Ideas Year 9 sciPAD 2025

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198 SCIPAD - BIG IDEAS - BOOK 1
LIFE OF ANIMALS
The Heart
Your heart is a hard-working, muscular pump. At the moment it is probably beating around 65
times a minute. The heart has two sides and when we talk about, or draw, a human heart it is
labelled as if it is inside you. For example, look at the diagram below. What appears to be the
right-hand side of the diagram has been labelled ‘the left-hand side’ of the heart.
Deoxygenated blood enters the heart via
the inferior vena cava (on the bottom)
and superior vena cava (on the top).
These blood vessels empty into the right
atrium. From here blood flows into the right
ventricle, before being pumped to the
lungs via the pulmonary artery. The word
pulmonary comes from the Latin word
pulmonem - meaning ‘of the lungs’. The
pulmonary artery is the only artery in the
body to carry deoxygenated blood. The
pulmonary artery divides in two shortly after
leaving the heart, in order to deliver blood
to the left and right lungs. Upon reaching
the lungs, the blood becomes oxygenated
and returns to the heart via the pulmonary
veins. The pulmonary veins are the only veins
in the body to carry oxygenated blood. The
pulmonary veins enter into the left atrium.
Blood flows from here into the left ventricle.
The left ventricle then contracts and sends oxygenated blood to the body via the aorta. The two
sides of the heart are divided by a wall called the septum.
The muscular walls of the left ventricle are thicker than the walls of the right ventricle. This is
because the right ventricle only needs to pump blood to the lungs, whereas the left ventricle
needs to pump blood around the entire body.
1. Use the information above to complete the flow diagram below. Some stages have been
done for you.
Vena Cava
Lungs
Aorta
2. Name the organs associated with the word pulmonary. 
3. All arteries carry oxygenated blood, except one. Name the artery that carries deoxygenated
blood. 
4. All veins carry deoxygenated blood, except one. Name the vein that carries oxygenated
blood. 
5. Name the wall that separates the left and right-hand side of the heart. 
6. Outline why the outer wall of the left ventricle is thicker than the outer wall of the right
ventricle. 

7. Why is one vena cava called superior while the other is called inferior? 

Left-hand side
of the heart
Right-hand side
of the heart
Right
Ventricle
Superior
and inferior
vena cava
Right
pulmonary
artery
Aorta
Left
pulmonary
artery
Pulmonary
veins
Left
Ventricle
Septum
Right
Atrium
Left
Atrium
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