Types of Circulatory System

10.1 Types of Circulatory System
 
 
The Necessity for Transport Systems in Complex Multicellular Organisms
  • Each living cell requires essential substances such as oxygen and nutrients, and expels cellular waste products such as carbon dioxide and nitrogenous wastes.
  • Unicellular organisms have a small body mass.
  • Therefore, the total surface area to volume ratio (TSA/V) of the organism is large.
  • As such, Amoeba sp. does not require a specialised transport system to transport substances in and out of the cell.
  • Large complex multicellular organisms cannot obtain essential substances and expel wastes by diffusion because their TSA/V is small.
  • The distance between the external environment and the cell is too far for direct substance exchange.
  • To address this problem, multicellular organisms have an internal transportation system.
  • In vertebrates, the transportation system is called the blood circulatory system.
 
Types of Circulatory Systems in Multicellular Organisms
  • The circulatory system in multicellular organisms is divided into two types: open circulatory system and closed circulatory system.
 
 
 
Open Circulatory System
Circulatory System of Insects
  • The circulatory system of insects is an open circulatory system.
  • This means that one or more hearts pump haemolymph through the blood vessels into the haemocoel.
  • Haemolymph flows out from the heart into the haemocoel when the heart contracts.
  • In the haemocoel, substance exchange between haemolymph and body cells occurs through diffusion.
  • When the heart relaxes, haemolymph flows back into the heart through tiny openings called ostium.
 
Closed Circulatory System
Circulatory System of Fish
  • The heart of the fish has two chambers, that is, an atrium (plural: atria) and a ventricle.
  • Blood that leaves the ventricle is pumped to the gill capillaries to enable gaseous exchange.
  • The gill capillaries carry blood to the blood vessels that transport oxygenated blood to systemic capillaries.
  • In the systemic capillaries, oxygen diffuses into the tissues while carbon dioxide diffuses from the tissue into the capillaries.
  • The deoxygenated blood is then returned to the heart atrium through the veins.
  • As the blood flows in one direction, the fish circulatory system is known as a single circulatory system.
Circulatory System of Amphibians
  • The heart of an amphibian has three chambers, that is, two atria and a ventricle.
  • Unlike the single circulatory system of fish, blood flows in two directions: pulmocutaneous circulation and systemic circulation.
  • Therefore, this system is known as a double circulatory system.
  • Amphibians are said to have an incomplete double circulatory system because the deoxygenated blood and the oxygenated blood are mixed.
  • Pulmocutaneous circulation transports blood to the lungs and skin, and the exchange of gases takes place here.
  • Systemic circulation transports oxygenated blood to the body tissues and returns the deoxygenated blood to the right atrium through the veins.
Circulatory System of Humans
  • The human heart consists of four chambers: two atria and two ventricles that are separated completely.
  • Humans have a double circulatory system.
  • This means that in one complete circulatory cycle, blood flows in the blood vessels through the heart twice.
  • As there are two different circulations, humans are said to have a complete double circulatory system because the deoxygenated blood and the oxygenated blood do not mix.

Pulmonary Circulation:

  • Deoxygenated blood is transported through the pulmonary artery to the lungs for gaseous exchange.
  • Oxygenated blood from the lungs is returned to the left atrium and flows into the left ventricle.

Systemic Circulation:

  • Blood is pumped from the heart to all the body tissues through the aorta.
  • Then the deoxygenated blood returns to the right atrium through vena cava.
 
Similarities of Circulatory Systems in Complex Multicellular Organisms
  • The circulatory system is found in all multicellular organisms, consists of a heart to pump blood or haemolymph (in insects), functions to transport nutrients and wastes.
  • The heart has valves that ensure blood flows in one direction.
 
 
 

Types of Circulatory System

10.1 Types of Circulatory System
 
 
The Necessity for Transport Systems in Complex Multicellular Organisms
  • Each living cell requires essential substances such as oxygen and nutrients, and expels cellular waste products such as carbon dioxide and nitrogenous wastes.
  • Unicellular organisms have a small body mass.
  • Therefore, the total surface area to volume ratio (TSA/V) of the organism is large.
  • As such, Amoeba sp. does not require a specialised transport system to transport substances in and out of the cell.
  • Large complex multicellular organisms cannot obtain essential substances and expel wastes by diffusion because their TSA/V is small.
  • The distance between the external environment and the cell is too far for direct substance exchange.
  • To address this problem, multicellular organisms have an internal transportation system.
  • In vertebrates, the transportation system is called the blood circulatory system.
 
Types of Circulatory Systems in Multicellular Organisms
  • The circulatory system in multicellular organisms is divided into two types: open circulatory system and closed circulatory system.
 
 
 
Open Circulatory System
Circulatory System of Insects
  • The circulatory system of insects is an open circulatory system.
  • This means that one or more hearts pump haemolymph through the blood vessels into the haemocoel.
  • Haemolymph flows out from the heart into the haemocoel when the heart contracts.
  • In the haemocoel, substance exchange between haemolymph and body cells occurs through diffusion.
  • When the heart relaxes, haemolymph flows back into the heart through tiny openings called ostium.
 
Closed Circulatory System
Circulatory System of Fish
  • The heart of the fish has two chambers, that is, an atrium (plural: atria) and a ventricle.
  • Blood that leaves the ventricle is pumped to the gill capillaries to enable gaseous exchange.
  • The gill capillaries carry blood to the blood vessels that transport oxygenated blood to systemic capillaries.
  • In the systemic capillaries, oxygen diffuses into the tissues while carbon dioxide diffuses from the tissue into the capillaries.
  • The deoxygenated blood is then returned to the heart atrium through the veins.
  • As the blood flows in one direction, the fish circulatory system is known as a single circulatory system.
Circulatory System of Amphibians
  • The heart of an amphibian has three chambers, that is, two atria and a ventricle.
  • Unlike the single circulatory system of fish, blood flows in two directions: pulmocutaneous circulation and systemic circulation.
  • Therefore, this system is known as a double circulatory system.
  • Amphibians are said to have an incomplete double circulatory system because the deoxygenated blood and the oxygenated blood are mixed.
  • Pulmocutaneous circulation transports blood to the lungs and skin, and the exchange of gases takes place here.
  • Systemic circulation transports oxygenated blood to the body tissues and returns the deoxygenated blood to the right atrium through the veins.
Circulatory System of Humans
  • The human heart consists of four chambers: two atria and two ventricles that are separated completely.
  • Humans have a double circulatory system.
  • This means that in one complete circulatory cycle, blood flows in the blood vessels through the heart twice.
  • As there are two different circulations, humans are said to have a complete double circulatory system because the deoxygenated blood and the oxygenated blood do not mix.

Pulmonary Circulation:

  • Deoxygenated blood is transported through the pulmonary artery to the lungs for gaseous exchange.
  • Oxygenated blood from the lungs is returned to the left atrium and flows into the left ventricle.

Systemic Circulation:

  • Blood is pumped from the heart to all the body tissues through the aorta.
  • Then the deoxygenated blood returns to the right atrium through vena cava.
 
Similarities of Circulatory Systems in Complex Multicellular Organisms
  • The circulatory system is found in all multicellular organisms, consists of a heart to pump blood or haemolymph (in insects), functions to transport nutrients and wastes.
  • The heart has valves that ensure blood flows in one direction.
 
 
 
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