Biomedical Engineering Reference
In-Depth Information
Fig. 2.3
Oxygen and carbon dioxide gas exchange. During breathing, gas exchange takes place
in the alveoli where oxygen is passed into the bloodstream while carbon dioxide and other waste
products are expelled. In the pulmonary circulatory system, the pulmonary artery is responsible for
transporting de-oxygenated blood away from the heart to the lungs. The pulmonary vein transports
oxygenated blood back to the heart. The oxygenation and de-oxygenation processes take place
simultaneously at the alveolar-capillary interface in the deep lung airways
veins around the body that prevent backflow from occurring by sealing off the ves-
sels when the heart is expanding (diastole), causing a lower pressure upstream.
2.1.2.2
Systemic Circulation
High pressure is exerted on the blood as it is squeezed out of the aorta in the left
ventricle to pass through to the whole body. Within this flow, the blood will absorb
nutrients attained from the digestion, which is then used to provide fuel for energy
and storage. The waste are taken away through the liver and then expelled from
the body. The vessel walls are smooth enough to allow for ease of flow and strong
enough to withstand the high pressure of the flow. Eventually, the de-oxygenated
blood carrying the waste product is returned to the heart. Due to greater distances
to be transported, the left ventricle muscle is stronger and provides the blood with
sufficient pressure to circulate it further.
2.1.2.3
Coronary Circulation
Oxygenated blood circulates through the heart via the coronary arteries, while deox-
ygenated blood is taken away to the lungs through the cardiac veins. The coronary
circulatory system is very much like the systemic circulatory system in the sense
that blood is supplied to the heart but via the coronary arteries. The heart and the
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