Search results
Results from the WOW.Com Content Network
Oxygenation zones are numbered inside the diamond-shaped acinus (in red). Zone three is closest to the central vein and zone one is closest to the portal triad. Zones differ by function: zone I hepatocytes are specialized for oxidative liver functions such as gluconeogenesis, β-oxidation of fatty acids and cholesterol synthesis
The zones of the lung divide the lung into four vertical regions, based upon the relationship between the pressure in the alveoli (PA), in the arteries (Pa), in the veins (Pv) and the pulmonary interstitial pressure (Pi): Zone 1: PA > Pa > Pv; Zone 2: Pa > PA > Pv; Zone 3: Pa > Pv > PA; Zone 4: Pa > Pi > Pv > PA
He proposed that the liver was the originating point of all blood vessels. He also theorized that the heart was not a pumping muscle but rather an organ through which blood passed. [24] Galen's theory included a new description of pulmonary circulation: air was inhaled into the lungs where it became the pneuma.
Diagram of the human heart showing blood oxygenation to the pulmonary and systemic circulation. The heart pumps blood to all parts of the body providing nutrients and oxygen to every 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 hepatic artery provides 30 to 40% of the oxygen to the liver, while only accounting for 25% of the total liver blood flow. The rest comes from the partially deoxygenated blood from the portal vein. The liver consumes about 20% of the total body oxygen when at rest.
The lungs are not capable of expanding to breathe on their own, and will only do so when there is an increase in the volume of the thoracic cavity. [71] This is achieved by the muscles of respiration, through the contraction of the diaphragm, and the intercostal muscles which pull the rib cage upwards as shown in the diagram. [72]
The increased lung pressure pushes the air out of the lungs. [2] The primary function of ventilation is the replacement of the stale gases in the lungs with oxygen-rich air through the removal of carbon dioxide for oxygenation of the blood. [5] The oxygen is then supplied to the entire body through the circulatory system.
The alveolar oxygen partial pressure is lower than the atmospheric O 2 partial pressure for two reasons. Firstly, as the air enters the lungs, it is humidified by the upper airway and thus the partial pressure of water vapour (47 mmHg) reduces the oxygen partial pressure to about 150 mmHg.