Mammalian Circulation (AQA AS Biology): Revision Note
Exam code: 7401
Blood circulation in mammals
- The mammalian circulatory system is a mass transport system that ensures that the cells of mammals receive a constant supply of reactants for metabolism, e.g.: - oxygen 
- glucose 
 
- The circulatory system in mammals is a closed circulatory system, in which blood flows inside enclosed vessels - In an open circulatory system, blood is not contained within blood vessels but is pumped directly into body cavities, e.g. in insects 
 
- Mammalian circulation is also described as a double circulatory system: for each complete circuit of the body, blood passes through the heart twice - The left side of the heart pumps blood around the body; this is the systemic circulatory system 
- The right side of the heart pumps blood deoxygenated blood to the lungs for gas exchange; this is the pulmonary circulatory system 
 
| Blood vessel | Associated organ(s) | Function | 
|---|---|---|
| Coronary arteries | Heart | Supply the heart with oxygenated blood | 
| Aorta | Heart | Carries oxygenated blood out of the heart and towards the body | 
| Vena cava | Heart | Carries deoxygenated blood into the heart from the body | 
| Pulmonary artery | Heart, lungs | carries deoxygenated blood away from the heart, towards the lungs | 
| Pulmonary vein | Heart, lungs | Carries oxygenated blood away from the lungs, towards the heart | 
| Renal artery | Heart, kidneys | Supplies the kidneys with oxygenated blood | 
| Renal vein | Heart, kidneys | Carries deoxygenated blood away from the kidneys, towards the heart | 

Examiner Tips and Tricks
The pulmonary vein is the only vein in the circulatory system that contains oxygenated blood.
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