Biology

Blood Circulation

Blood Circulation

Blood Circulation

• Blood circulation is essential for all animals as it transports oxygen and nutrients to body tissues.
• Different organisms have unique circulation pathways to meet their specific needs.

Common Objective

• The primary goal of blood circulation is to transport oxygenated blood to body tissues.

Double Circulation

• In amphibians, reptiles, mammals, and birds, blood undergoes double circulation:
  • First Circuit: Blood is pumped to the lungs (or gills in fish) for oxygenation.
  • Second Circuit: Oxygenated blood returns to the heart and is then distributed to the rest of the body.

Single Circulation

• In fish, a simpler circulation system is observed known as single circulation:
  • Blood leaves the gill capillaries and travels directly to body tissues.
  • It then returns to the heart.

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Blood Circulation

Unique Heart Structures

Different animals possess distinct heart structures to facilitate their specific circulation patterns.

• Fish: Two-chambered heart with one atrium and one ventricle for single circulation.
• Amphibians and Reptiles: Three-chambered heart with two atria and one ventricle for double circulation.
• Mammals and Birds: Four-chambered heart with two atria and two ventricles for double circulation.

Efficiency and Adaptations

• The heart structures and circulation patterns are adapted to each organism's metabolic needs and environment.
• Single circulation in fish is suitable for extracting oxygen from water using gills.
• Double circulation in mammals and birds allows for efficient separation of oxygenated and deoxygenated blood, supporting higher metabolic rates.