Editing Circulatory system (section)

===Heart===
{{Main|Heart}}
[[File:Blood oxygenation to the pulmonary and systemic circulation.svg|thumb|Diagram of the human [[heart]] showing blood oxygenation to the pulmonary and systemic circulation|border]]
The heart pumps blood to all parts of the body providing [[nutrient]]s and [[oxygen]] to every [[Cell (biology)|cell]], and removing waste products. The left heart pumps oxygenated blood returned from the lungs to the rest of the body in the [[systemic circulation]]. The right heart pumps deoxygenated blood to the lungs in the [[pulmonary circulation]]. In the human heart there is one [[Atrium (heart)|atrium]] and one [[Ventricle (heart)|ventricle]] for each circulation, and with both a systemic and a pulmonary circulation there are four chambers in total: [[left atrium]], [[left ventricle]], [[right atrium]] and [[right ventricle]]. The right atrium is the upper chamber of the right side of the heart. The blood that is returned to the right atrium is deoxygenated (poor in oxygen) and passed into the right ventricle to be pumped through the pulmonary artery to the lungs for re-oxygenation and removal of carbon dioxide. The left atrium receives newly oxygenated blood from the lungs as well as the pulmonary vein which is passed into the strong left ventricle to be pumped through the aorta to the different organs of the body.

====Pulmonary circulation====
{{Main|Pulmonary circulation}}
[[File:2119 Pulmonary Circuit.jpg|thumb|370px|right|The [[pulmonary circulation]] as it passes from the [[heart]]. Showing both the [[Pulmonary artery|pulmonary]] and [[Bronchial artery|bronchial arteries]].]]
The pulmonary circulation is the part of the circulatory system in which [[Deoxygenated blood|oxygen-depleted blood]] is pumped away from the heart, via the [[pulmonary artery]], to the [[lungs]] and returned, oxygenated, to the heart via the [[pulmonary vein]].

Oxygen-deprived blood from the superior and inferior [[vena cava]] enters the right atrium of the heart and flows through the [[tricuspid valve]] (right atrioventricular valve) into the right ventricle, from which it is then pumped through the [[pulmonary semilunar valve]] into the pulmonary artery to the lungs. [[Gas exchange]] occurs in the lungs, whereby {{CO2|link=yes}} is released from the blood, and oxygen is absorbed. The pulmonary vein returns the now oxygen-rich blood to the [[left atrium]].<ref name="Guyton"/>

A separate circuit from the systemic circulation, the [[bronchial circulation]] supplies blood to the tissue of the larger airways of the lung.

====Systemic circulation====
[[File:2105 Capillary Bed.jpg|thumb|upright=1.4|Capillary bed]]
[[File:Capillary system CERT.jpg|thumb|Diagram of capillary network joining the arterial system with the venous system]]

The systemic circulation is a circuit loop that delivers oxygenated blood from the left heart to the rest of the body through the [[aorta]]. Deoxygenated blood is returned in the systemic circulation to the right heart via two large veins, the [[inferior vena cava]] and [[superior vena cava]], where it is pumped from the right atrium into the pulmonary circulation for oxygenation. The systemic circulation can also be defined as having two parts – a macrocirculation and a [[microcirculation]].<ref name="Guyton"/>