Heart structure
Laura Armstrong & Joe Wolfensohn
Teachers
Contents
Recall Questions
This topic requires prior knowledge of the circulatory system from GCSE. You can test your knowledge on this below.
What are the four chambers of the human heart, and what are their functions?
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Right atrium: Receives deoxygenated blood from the body via the vena cava.
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Right ventricle: Pumps deoxygenated blood to the lungs via the pulmonary artery.
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Left atrium: Receives oxygenated blood from the lungs via the pulmonary veins.
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Left ventricle: Pumps oxygenated blood to the body via the aorta.
Why is the left ventricle’s wall thicker than the right ventricle’s?
The left ventricle pumps blood to the entire body under high pressure, requiring a thicker muscle wall, while the right ventricle only pumps blood to the lungs, which is a shorter distance and requires lower pressure.
What is the role of the coronary arteries?
The coronary arteries supply oxygenated blood and nutrients to the heart muscle to ensure continuous contraction and function.
Topic Explainer Video
Check out this @JoeDoesBiology video that explains heart structure or read the full notes below. Once you've gone through the whole note, try out the practice questions!
Overview of the Heart’s Structure
- The heart is a four-chambered muscular organ responsible for pumping blood around the body.
- It consists of two atria (upper chambers) and two ventricles (lower chambers).
- The septum separates the left and right sides to prevent the mixing of oxygenated and deoxygenated blood.
- Valves (atrioventricular and semi-lunar) ensure unidirectional blood flow and prevent backflow.
Differences in Muscle Wall Thickness
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Left ventricle:
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Thickest muscular wall, to increase force of contraction, as it pumps blood under high pressure through the systemic circulation to the entire body.
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Right ventricle:
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Thinner than the left ventricle because it pumps blood only to the lungs under lower pressure to prevent damage to the delicate capillaries in the lungs.
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Atria:
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Thinner walls than ventricles as they only receive blood and pump it into the ventricles.
Role of the Coronary Arteries
- The coronary arteries supply oxygenated blood and nutrients to the heart muscle.
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These arteries branch off from the aorta immediately after blood leaves the heart.
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If blocked (e.g., by atherosclerosis), it can lead to coronary heart disease or a heart attack (myocardial infarction).
Key Terms
- Atria: Upper chambers that receive blood.
- Ventricles: Lower chambers that pump blood.
- Septum: Wall separating the left and right sides of the heart.
- Valves: Prevent backflow of blood.
- Coronary arteries: Supply blood to the heart muscle.
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Exam Tip
Be able to label a diagram of the heart and describe the flow of blood through its chambers.
No answer provided.
Explain why the left ventricle has a thicker wall than the right ventricle. (2 marks)
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The left ventricle has a thicker wall because it pumps blood to the entire body under high pressure, whereas the right ventricle only pumps blood to the lungs under lower pressure (1 mark).
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The higher pressure in the systemic circuit ensures that oxygen and nutrients reach all body tissues efficiently (1 mark).
Practice Question
Try to answer the practice question from the TikTok on your own, then watch the video to see how well you did!