|
|
Blood is a liquid with suspended cells 30-50% by volume. These cells are of three basic types, erythrocytes or rbcs, leucocytes or wbcs and thrombocytes or platelets. Two of these three cell types are odd, in being anucleate. All originate in the bone marrow, although the number of primary stem cell types is unresolved.
The circulatory system is the route by which the cells in your body get the oxygen and nutrients they need, but the blood is the actual carrier of the oxygen and nutrients. Blood is made mostly of plasma, which is a yellowish liquid that is 90% water. But in addition to the water, plasma contains salts, sugar (glucose), and other substances. And, most important, plasma contains proteins that carry important nutrients to the body’s cells and strengthen the body’s immune system so it can fight off infection.
The average man has between 10 and 12 pints of blood in his body. The average woman has between 8 and 9 pints. To give you an idea of how much blood that is, 8 pints is equal to 1 gallon (think of a gallon of milk).
What is blood?
Blood is actually a tissue. It is thick because it is made up of a variety of cells, each having a different job. In fact, blood is actually about 80% water and 20% solid.
We know that blood is made mostly of plasma. But there are 3 main types of blood cells that circulate with the plasma:
Platelets, which help the blood to clot. Clotting stops the blood from flowing out of the body when a vein or artery is broken. Platelets are also called thrombocytes.
Red blood cells, which carry oxygen. Of the 3 types of blood cells, red blood cells are the most plentiful. In fact, a healthy adult has about 35 trillion of them. The body creates these cells at a rate of about 2.4 million a second, and they each have a life span of about 120 days. Red blood cells are also called erythrocytes.
White blood cells, which ward off infection. These cells, which come in many shapes and sizes, are vital to the immune system. When the body is fighting off infection, it makes them in ever-increasing numbers. Still, compared to the number of red blood cells in the body, the number of white blood cells is low. Most healthy adults have about 700 times as many red blood cells as white ones. White blood cells are also called leukocytes.
Blood also contains hormones, fats, carbohydrates, proteins, and gases.
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.
>>
HISTORY OF HOSPITALS
