Evolution of the animal circulatory system

In this topic

• Why a transport system was needed
• From no system at all to the first blood vessels
• The open (lacunar) system, and the improvement of the blood
• The chordate heart: 2 → 3 → 4 chambers

Key terms

• Circulatory system
• Closed circulatory system
• Open (lacunar) system
• Haemolymph
• Heart
• Atrium
• Ventricle
• Circle of circulation
• Haemoglobin
• Haemocyanin
• Erythrocyte
• Warm-bloodedness

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