The Circulatory System
Applied Science: BTEC Level 3 National Extended Diploma, topic 4.5.1
The Circulatory System
Complex multicellular organisms require a specialised system for transporting nutrients throughout their bodies and removing waste products.
Heart
- The heart is the centre of the circulatory system.
- Mammals have a double circulatory system. This means blood flows through the heart twice in one circuit.
- Deoxygenated blood is pumped to the lungs.
- Oxygenated blood is pumped around the body.
Coronary arteries
- The heart is a muscle that is constantly contracting and relaxing.
- The heart muscle needs a constant supply of oxygen for respiration.
- The coronary arteries supply blood to the heart.
Pulmonary artery & vein
- Deoxygenated blood is pumped out of the heart to the lungs via the pulmonary artery.
- Oxygen diffuses into the deoxygenated blood in the lungs and the blood becomes oxygenated.
- Oxygenated blood flows into the heart from the lungs via the pulmonary vein.
Aorta & vena cava
- Oxygenated blood is pumped out of the heart around the body via the aorta.
- Blood in the aorta is very high pressure to ensure the blood can be pumped to all the tissues in the body.
- Oxygen dissociates from the blood at respiring cells in the body and the blood becomes deoxygenated.
- Deoxygenated blood flows into the heart from the body via the vena cava.
Renal artery & vein
- Oxygenated blood flows out of the aorta to the kidneys.
- Oxygenated blood enters the kidneys through the renal artery.
- Oxygen diffuses out of the blood to be used in the kidney cells and the blood becomes deoxygenated.
- Deoxygenated blood flows out of the kidneys via the renal vein.
Test yourself on The Circulatory System
Where is deoxygenated blood from the heart pumped to?
Which of the following statements about the circulatory system are true?