mass transport in animals

• Closed circulatory system in animals: blood stays inside the vessels, while a separate fluid bathes the tissues and cells
• The heart pumps blood at a higher pressure for quicker flow, allowing quick delivery of oxygen and nutrients and fast removal of waste
• Valves maintain the flow of blood in the circulatory system
• Single circulation: blood pressure is reduced as it passes through the gill capillaries, limiting the rate of oxygen and nutrient delivery to cells
• Efficient in fish but not in mammals
• Double circulation is more efficient in mammals
• The heart is composed of two different pumps, left and right
• Allows for higher levels of activity and maintenance of body temperature