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Structure of the heart, blood and circulation

Organisation • Animal tissues, organs and systems

Key concepts

What you'll likely be quizzed about

  • The heart comprises two atria (upper chambers) and two ventricles (lower chambers).
  • Valves between these chambers and at major arteries prevent backflow, allowing contractions to propel blood forward through the heart.
  • The separation of the right and left sides prevents mixing oxygenated and deoxygenated blood.
  • Blood from the lungs enters the left atrium, moves into the left ventricle, and is pumped into the aorta for distribution throughout the body.
  • Blood returns from the body to the right atrium, progresses into the right ventricle, and is sent to the lungs via the pulmonary artery for gas exchange.
  • The pulmonary vein brings oxygenated blood back to the left atrium.

Flashcards

Test your knowledge with interactive flashcards

State the function of the right ventricle.

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Pumps deoxygenated blood into the pulmonary artery for gas exchange in the lungs, with thinner walls compared to the left ventricle.

Key notes

Important points to keep in mind

Left ventricle walls are thicker than right ventricle walls for greater pressure in systemic circulation.

Blood composition is approximately 55% plasma and 45% cells.

Arteries have thick muscular and elastic walls for high-pressure blood flow.

Veins feature wide lumens and valves to assist with low-pressure blood return.

Capillaries are one cell thick for efficient diffusion of gases and nutrients.

Red blood cell adaptations enhance oxygen transport efficiency.

Pacemaker cells in the right atrium regulate the heart rate; artificial devices assist when necessary.

Coronary arteries provide blood to the heart muscle; blockages can risk heart attack.

Alveoli optimize gas exchange through their unique structures.

Use consistent units in rate calculations. Cardiac output can be estimated as stroke volume multiplied by heart rate.

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