Blood is a type of connective tissue, a fluid made of 4 major substances:
Approx. 5 million RBC's, 7,500 WBC's, and 300,000 platelets are found in 1 drop of blood, approx 30 trillion RBC's in entire body.
Blood = 8% of body weight, approx. 5-6 qts.(10-12
pints), pH of 7.4, temperature = 100 degrees Fahrenheit.
Manufacture of Blood
Myeloid tissue (red bone marrow) produces 2 million
RBC's each second because RBC's live only about 120 days. Myeloid tissue,
found in the sternum, ribs, hipbones, and clavicles, manufacture most of
the blood except for some types of white blood cells which are produced
in the lymphatic tissue.
FUNCTIONS OF BLOOD
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RED BLOOD CELL FUNCTIONS: Transport oxygen - Unique
structure and tremendous numbers give the RBC's a total surface area larger
than a football field for absorbing oxygen.
HEMOGLOBIN - an iron containing protein that combines
with oxygen to form OXYHEMOGLOBIN which carries oxygen to the body. Each
erythrocyte contains approx. 280 million molecules of hemoglobin.
ANEMIA - a number of different conditions caused by an inability to carry sufficient oxygen to the body cells due to:
TYPES OF ANEMIA:
POLYCYTHEMIA - Almost the opposite of anemia; the
red bone marrow produces too many RBC's.
Blood Doping - An artificial way of raising red blood cell levels involving tranfusions by athletes to raise their level of RBC's and increase oxygen delivery to muscles (Illegal for competition and probably inadvisable anyway).
HEMATOCRIT - A blood test that uses a centrifuge
to separate and measure the different portions of blood.
RBC's = 45% in normal blood
Buffy Coat - made of WBC's and platelets
Plasma = approx 50% of blood
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WHITE BLOOD CELL FUNCTIONS
DISORDERS OF WHITE BLOOD CELLS:
As platelets collect around an injured vessel, some break up and release PLATELET FACTORS which combine with PROTHROMBIN (a protein found in the plasma) to form THROMBIN (an enzyme) that changes FIBRINOGEN to FIBRIN, a gel-like fiber that catches RBC's and forms the clot.
VITAMIN K - stimulates liver to increase production of prothrombin.
THROMBUS - a blood clot
THROMBOSIS - the condition of having a blood clot
EMBOLUS - a dislodged clot
EMBOLISM - the condition of having a dislodged blood clot
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here to identify Leukocytes
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Click here to learn about Karl Landsteiner, discoverer of Blood types
O = 45% - UNIVERSAL DONOR
A = 41%
B = 10%
AB = 4% - UNIVERSAL RECIPIENT
ANTIGEN - a substance that stimulates the production of antibodies
ANTIBODY - a substance that reacts to an antigen, usually causing them to clump together
AGGLUTINATE - clumping of antibodies and antigens
The blood types are caused by the presence or absence of two types of
proteins that act as antigens in the blood (see the chart below.) Those
with the first protein are called Type A. Those with the second protein
are called Type B. Some people have both and are called Type AB. Some people
don't have either protein. They are called type O. Reactions between the
antibodies and antigens of different blood types causes clumping (agglutination)
of the cells.
In addition to these blood types, blood type is identified as to the presence or absence of a blood protein called Rh factor. Those with the factor are said to be positive. Those without the factor are said to be negative (chart below.)
|BLOOD TYPE||BLOOD PROTEIN (ANTIGEN)||BLOOD ANTIBODY|
|AB||A & B||Neither A nor B|
|O||Neither A nor B||Both Anti-A & Anti-B|
|Rh Factor||Rh PROTEIN (ANTIGEN)||Rh ANTIBODY|
|Rh positive||Rh Antigen||No Rh antibody|
|Rh negative||No Rh Antigen||Can develop antibodies if exposed|
Rh FACTOR - an antigen found in 85% of human blood. The name Rh was
chosen because it was first discovered in the blood of the Rhesus monkey.
People without the factor (negative) do not have antibodies against the
factor, but will develop them if exposed to Rh factor through blood transfusion
ERYTHROBLASTOSIS FETALIS - a disorder caused by the reaction of an Rh
negative mother carrying an Rh positive child. It happens to the second
positive child of an Rh negative mother and may cause death. This can be
prevented if the mother receives a shot to prevent the production of antibodies
after each birth.
INHERITANCE OF BLOOD TYPE:
The inheritance of blood is an example of a genetic condition known
as multiple allelles. This means that it is a little more complicated than
the simple dominant / recessive traits that we usually discuss. Blood types
A and B are what is known as co-dominant. When both are inherited, both
will be expressed. Neither is recessive to the other. Both A and B, however,
are dominant to the inheritance of O, which is the lack or either A or
We use the lowercase letter i to represent the recessive type O. The
genotypes (possible gene combinations) for blood type can be represented
by the chart below:
|BLOOD TYPE||Possible Genotypes|
|A||AA or Ai|
|B||BB or Bi|
Rh factor is inherited separately from blood type. The inheritance of
Rh factor (positive) is dominant to the inheritance of negative (no Rh