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Biology > The Heart

The heart is made from cardiac muscle which does not tire and is incredibly strong Cardiac muscle can contract by itself and does not need nerve impulses to achieve this. The heart is essentially a powerful pump which runs continuously without relaxing. It consists of four chambers. The upper two chambers are known as the atria whereas the bottom two are called ventricles.

The diagram below shows the composition of the heart with the labels indicating the position of the internal parts.

The Heart
Fig 1:
The Heart

The table below shows the relative heart rates of various animals along with the longevity of the animal and an estimate of the amount of heartbeats which take place during the life of the animal.

Creature Heart Rate (/minute) Longevity (years) Lifetime Heartbeats (billions)
Human 60 70 2.21
Cat 150 15 1.18
Small dog 100 10 0.53
Medium dog 90 15 0.71
Large dogs 75 17 0.67
Hamster 450 3 0.71
Chicken 275 15 2.17
Monkey 190 15 1.50
Horse 44 40 0.93
Cow 65 22 0.75
Pig 70 25 0.92
Rabbit 205 9 0.97
elephant 30 70 1.1
giraffe 65 20 0.68
large whale 20 80 0.84