9.2 Heart

2026 Syllabus Objectives

  1. Identify in diagrams and images the structures of the mammalian heart, limited to: muscular wall, septum, left and right ventricles, left and right atria, one-way valves and coronary arteries
  2. State that blood is pumped away from the heart in arteries and returns to the heart in veins
  3. State that the activity of the heart may be monitored by: ECG, pulse rate and listening to sounds of valves closing
  4. Investigate and describe the effect of physical activity on the heart rate
  5. Describe coronary heart disease in terms of the blockage of coronary arteries and state the possible risk factors including: diet, lack of exercise, stress, smoking, genetic predisposition, age and sex
  6. Discuss the roles of diet and exercise in reducing the risk of coronary heart disease
  7. Identify in diagrams and images the atrioventricular and semilunar valves in the mammalian heart
  8. Explain the relative thickness of: (a) the muscle walls of the left and right ventricles (b) the muscle walls of the atria compared to those of the ventricles
  9. Explain the importance of the septum in separating oxygenated and deoxygenated blood
  10. Describe the functioning of the heart in terms of the contraction of muscles of the atria and ventricles and the action of the valves
  11. Explain the effect of physical activity on the heart rate

Structure of the Heart 🫀

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Function of the Heart

The function of the heart is to pump blood around the body. The heart is made of a special type of muscle that contracts and relaxes regularly, throughout life, enabling continuous blood circulation.

Heart Chambers

The heart is divided into four chambers:

Upper Chambers - Atria (singular: atrium)

  • Thin-walled chambers at the top of the heart
  • Receive blood from veins
  • The left atrium receives oxygenated blood from the pulmonary veins (from the lungs)
  • The right atrium receives deoxygenated blood from the venae cavae (from the body)

Lower Chambers - Ventricles

  • Thick-walled chambers at the base of the heart
  • Pump blood out of the heart into arteries
  • The left ventricle pumps oxygenated blood into the aorta (to the body)
  • The right ventricle pumps deoxygenated blood into the pulmonary artery (to the lungs)

The Septum

The septum is the muscular wall that completely separates the left and right sides of the heart. This structure is crucial because it:

  • Keeps oxygenated blood separate from deoxygenated blood
  • Prevents mixing of blood from the two sides
  • Ensures that fully oxygenated blood is delivered to body tissues
  • Maintains efficient oxygen delivery to cells

🔑 Key Point: The septum ensures that oxygenated blood from the lungs does not mix with deoxygenated blood from the body, maintaining maximum oxygen delivery efficiency.

Major Blood Vessels

Blood VesselTypeFunctionBlood Type
AortaArteryCarries blood from left ventricle to bodyOxygenated
Pulmonary arteryArteryCarries blood from right ventricle to lungsDeoxygenated
Pulmonary veinsVeinsCarry blood from lungs to left atriumOxygenated
Venae cavaeVeinsCarry blood from body to right atriumDeoxygenated

📌 Remember: Arteries carry blood away from the heart, while veins carry blood towards the heart.

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