Facts about Blood
Blood Types and Breakdown of Population by
How Much Blood Does a Person Have?
Blood Donation Procedures (For "official"
Blood Storage & Breakdown
Whole Blood is a living tissue that circulates through the heart, arteries, veins and capillaries carrying nourishment, electrolytes, hormones, vitamins, antibodies, heat and oxygen to the body's tissues. Whole Blood contains Red Blood Cells, White Blood Cells and Platelets suspended in a pertinacious fluid called Plasma.
If blood is treated to prevent clotting and permitted
to stand in a container, the Red Blood Cells, weighing the most, will settle
to the bottom; the Plasma will stay on top; and the White Blood Cells and
Platelets will remain suspended between the Plasma and the Red Blood Cells.
A centrifuge may be used to hasten this separation process. The platelet-rich
plasma is then removed and placed into a sterile bag, and it can be used
to prepare Platelets and Plasma or Cryoprecipitated AHF. To make Platelets,
the platelet-rich plasma is centrifuged, causing the Platelets to settle
at the bottom of the bag. Plasma and Platelets are then separated and made
available for transfusion. The Plasma may also be pooled with Plasma from
other donors and further processed, or fractionated, to provide purified
Plasma proteins such as albumin, immunoglobulin and clotting factors.
Red Blood Cells are perhaps the most recognizable component of Whole Blood. Red Blood Cells contain hemoglobin, a complex iron-containing protein that carries oxygen throughout the body and gives blood its red color. The percentage of blood volume composed of Red Blood Cells is called the hematocrit; The average hematocrit in an adult male is 47 percent. There are about one billion Red Blood Cells in two to three drops of blood, and, for every 600 Red Blood Cells, there are about 40 Platelets and one white cell. Manufactured in the bone marrow, Red Blood Cells are continuously being produced and broken down. They live for approximately 120 days in the circulatory system and are eventually removed by the spleen.
Red Blood Cells are prepared from Whole Blood by removing
the Plasma, or the liquid portion of the blood, and can raise the patient's
hematocrit and hemoglobin levels while minimizing an increase in blood
volume. Patients who benefit most from transfusions of Red Blood Cells
include those with chronic anemia resulting from disorders such as kidney
failure, malignancies, or gastrointestinal bleeding and those with acute
blood loss resulting from trauma or surgery. Since Red Blood Cells have
reduced amounts of Plasma, they are well-suited for treating anemia patients
who would not tolerate the increased volume provided by whole blood, such
as patients with congestive heart failure or those who are elderly or debilitated.
Red Blood Cells may be treated and frozen for extended storage (up to 10
Plasma is the liquid portion of the blood, a protein-salt solution in which red and White Blood Cells and Platelets are suspended. Plasma, which is 90 percent water, constitutes about 55 percent of blood volume. Plasma contains albumin (the chief protein constituent), fibrinogen (responsible, in part, for the clotting of blood), globulins (including antibodies) and other clotting proteins. Plasma serves a variety of functions, from maintaining a satisfactory blood pressure and volume to supplying critical proteins for blood clotting and immunity. It also serves as the medium of exchange for vital minerals such as sodium and potassium, thus helping maintain a proper balance in the body, which is critical to cell function. Plasma is obtained by separating the liquid portion of blood from the cells.
Fresh Frozen Plasma is frozen within hours after donation to preserve clotting factors, stored for one to seven years, and thawed before it is transfused. It is most often used to treat certain bleeding disorders when a clotting factor or multiple factors are deficient and no factor-specific concentrate is available. It can also be used for Plasma replacement via a process called plasma exchange.
is the portion of Plasma that is rich in certain clotting factors, including
Factor VIII, fibrinogen, von Willebrand factor and Factor XIII. Cryoprecipitated
AHF is removed from Plasma by freezing and then slowly thawing the Plasma.
It is used to prevent or control bleeding in individuals with hemophilia
and von Willebrand disease, which are common, inherited major
coagulation abnormalities. Its use in these conditions is reserved for
times when viral-inactivated concentrates containing Factor VIII and von
Willebrand factor are unavailable and Plasma components must be used.
Platelets (or thrombocytes) are very small cellular components of blood that help the clotting process by sticking to the lining of blood vessels. Platelets are made in the bone marrow and survive in the circulatory system for an average of 9-10 days before being removed from the body by the spleen. The Platelet is vital to life, because it helps prevent both massive blood loss resulting from trauma and blood vessel leakage that would otherwise occur in the course of normal, day-to-day activity. Units of Platelets are prepared by using a centrifuge to separate the platelet-rich Plasma from the donated unit of Whole Blood. The Platelet-rich Plasma is then centrifuged again to concentrate the Platelets further.
Platelets may also be obtained from a donor by a process
known as apheresis, or plateletpheresis. In this process, blood is drawn
from the donor into an apheresis instrument, which, using centrifugation,
separates the blood into its components, retains the Platelets, and returns
the remainder of the blood to the donor. The resulting component contains
about six times as many Platelets as a unit of Platelets obtained from
Whole Blood. Platelets are used to treat a condition called thrombocytopenia,
in which there is a shortage of Platelets, and in patients with abnormal
Platelet function. Platelets are stored at room temperature for up to five
White Blood Cells are responsible for protecting the body from invasion by foreign substances such as bacteria, fungi and viruses. The majority of White Blood Cells are produced in the bone marrow, where they outnumber Red Blood Cells by two to one. However, in the blood stream, there are about 600 Red Blood Cells for every White Blood Cell. There are several types of White Blood Cells. Granulocytes and macrophages protect against infection by surrounding and destroying invading bacteria and viruses, and lymphocytes aid in the immune defense.
Granulocytes can be collected by apheresis or by centrifugation
of Whole Blood. They are transfused within 24 hours after collection and
are used for infections that are unresponsive to antibiotic therapy. The
effectiveness of White Blood Cell transfusion is still being investigated.
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