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happens to your blood after donation. 
What is blood?
Blood is a living tissue that circulates through
the heart, arteries, veins and organs carrying nourishment,
electrolytes, hormones, vitamins, antibodies, heat and oxygen to
the body’s tissues.
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Who needs blood?
The need for blood is great. Blood transfusions
often are needed for trauma victims — due to accidents and burns —
heart surgery, organ transplants, and patients receiving treatment
for leukemia, cancer or other diseases, such as sickle cell disease
and thalassemia. An aging population and advances in medical
treatments and procedures requiring blood transfusions also
continue to increase the demand for blood.
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What are the types of blood and who has them?
Blood types by percentage of population are as
follows:
- O positive, 37 percent
- O negative, 7 percent
- A positive, 36 percent
- A negative, 6 percent
- B positive, 8 percent
- B negative, 2 percent
- AB positive, 3 percent
- AB negative, 1 percent
In an emergency, anyone can receive O negative blood, and those
with O negative blood are known as “universal donors.”
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How much blood does a human body have?
An average size female has about nine pints of
blood, while an average size male has about 12 pints of
blood.
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How does the body make blood?
Red cells, platelets and white cells are made in
the bone marrow. Coagulation proteins (clotting factors) are made
in the liver and water comes from the body’s general fluid
content.
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What is whole blood?
Whole blood is just as it sounds – it is blood with
all of its components intact. Whole blood is comprised of red blood
cells, white blood cells and platelets suspended in a proteinaceous
fluid called plasma. These parts can be separated from whole blood
in order to provide patients with superior treatment by giving them
the specific elements they need. Whole blood donations can be made
every eight weeks (56 days).
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What are red blood cells?
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.
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How are red blood cells used?
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.
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What is plasma?
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 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.
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How is plasma used?
Plasma 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 through a process called plasma
exchange.
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What are platelets?
Platelets (or thrombocytes) are very small cellular
components of blood that help the clotting process by sticking to
the lining of blood vessels (basically, they form scabs). 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 through a process known
as automation. In this process, blood is drawn from the donor into
an automation 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 stored at room temperature
for up to five days.
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How are platelets used?
Platelets are used to treat a condition called
thrombocytopenia, in which there is a shortage of platelets, and to
prevent bleeding in patients with abnormal platelet function.
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What are white blood cells?
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 through automation or by centrifugation of whole blood
and are transfused within 24 hours after collection.
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How are white blood cells used?
White blood cells are used to fight infections that
are unresponsive to antibiotic therapy and to produce interferon.
The effectiveness of white blood cell transfusion is still being
investigated.
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