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In pulmonary circulation, deoxygenated blood returning from the organs and tissues of the body travels from the right atrium of the heart to the right ventricle. From there it is pushed through the pulmonary artery to the lung. In the lung, the pulmonary artery divides, forming the pulmonary capillary region of the lung.
At this site, microscopic vessels pass adjacent to the alveoli, or air sacs of the lung, and gases are exchanged across a thin membrane: oxygen crosses the membrane into the blood while carbon dioxide leaves the blood through this same membrane. Newly oxygenated blood then flows into the pulmonary veins, where it is collected by the left atrium of the heart, a chamber that serves as collecting pool for the left ventricle. The contraction of the left ventricle sends blood into the aorta, completing the circulatory loop. On average, a single blood cell takes roughly 30 seconds to complete a full circuit through both the pulmonary and systemic circulation.
HISTORY OF HOSPITALS:
Today the United States is home to 6,021 hospitals that contain over 1 million hospital beds. U.S.hospitals annually admit some 34 million patients who are assigned a bed and receive medical or surgical treatment as inpatients. Hospitals also provide outpatient treatment in clinics or other walk-in, or ambulatory, settings for an additional 483 million patients every year.
Hospitals in the United States are classified by the services they provide (general or specialized), the length of stay they offer patients (short stay or long-term care), and by their ownership (not-for-profit, proprietary, or government owned). Although most U.S. hospitals are classified as not-for-profit, any one hospital will fall into several of the above categories. For example, Methodist Hospital in Houston, Texas, with more than 300,000 sq m (3 million sq ft) of space, is one of the largest short-stay, not-for-profit, general hospitals in the country.
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HISTORY OF HOSPITALS
