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The circulatory system
- The heart is a double pump – Arteries take blood away from the heart while veins take blood to the heart. The right (left as you look at the diagram, right in real life) takes deoxygenated blood to the heart, while the left takes oxygenated blood around the body.
- Arteries carry blood at high pressure
- As a rule arteries carry oxygenated blood while veins carry deoxygenated blood. However, the pulmonary vein and artery break this rule and carry the opposite type of blood.
- The arteries split off into thousands of tiny capillaries and take blood to every cell
- The veins transport the deoxygenated blood at low pressure back to the heart.
💡The heart is made to pump by little pulses of electricity from the wall of the right atrium.💡
Diagram 1: the mechanism of circulatory system
The heart
In I/GCSE Biology, the heart pumps in three stages:
- Blood flows into the two atria.
- The atria gently push the blood into the ventricles (the sphincter muscles which let the blood into the atria from the vena cava and pulmonary vein close to stop blood flowing back out).
- The ventricle contracts pushing blood around the aorta and pulmonary artery. The valves presented in the heart stop backflow of blood.
💡The left side of the heart has a thick muscular wall because it needs to pump blood around the whole body💡
Diagram 2: the labelled diagram of a heart
There are various useful words concerning the heart in I/GCSE Biology.
- Bicuspid valve – The valve between the left atrium and left ventricle
- Tricuspid valve – The valve between the right atrium and ventricle
- Heart tendons/heart strings – are attached to the valves and stop them flipping inside out
- Septum – Muscular wall between the right and the left of he heart
- Semi lunar valves – the valves between the right ventricle and the pulmonary artery
That's the end of the topic!
Drafted by Joey (Biology)