Functions of Blood
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Transport of dissolved substances
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Regulation of pH and ions
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Restriction of fluid losses at injury sites
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Defense against toxins and pathogens
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Stabilization of body temperature
The Composition of Whole Blood
• Blood volume (liters) = 7% of body weight
– Adult male: 5 to 6 liters
– Adult female: 4 to 5 liters
• Three General Characteristics of Blood
– 38°C (100.4°F) is normal temperature
– High viscosity
– Slightly alkaline pH (7.35–7.45)
Plasma Is the Fluid Part of Blood
• Plasma = 55% of whole blood
– Made up of mostly water (92%)
– Other substances (8%)
– Used to transport:
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Blood cells and platelets
Proteins
Hormones
Ions
Nutrients, e.g., sugars and amino acids
Various gases
The Composition of Whole Blood
• Three Types of Cells (makes up 45%
of whole blood)
– Red blood cells (RBCs): Transport
oxygen.
• The oxygen binds to a special iron based
protein called hemoglobin found on the
RBC.
– White blood cells (WBCs): Part of the
immune system.
– Platelets: Cell fragments involved in
clotting.
• Clotting: The process of plugging a
damaged blood vessel to decrease blood
loss.
Production of Red Blood Cells
• They are produced in the red bone
marrow found in certain bones in our
body (arms, legs, hips)
– They mature from stem cells found inside
the bones.
• In a healthy person RBC count is
between 4-6 million RBC/ml of blood.
• RBC live for about 120 days.
How Clotting Works
Blood Typing
• There are 4 different blood types individuals can have A,
B, O, and AB.
– They are genetically determined.
• To determine which blood type is present you have to
look at the cells membrane’s proteins.
– These surface proteins are called antigens.
– Each blood type has its own specific combination of antigens
present.
– Your body cells are able to tell the difference between your
antigens and someone else’s antigens.
– If you body recognizes the antigens a foreign (called non-self
antigens) it will cause an immune response and try to destroy
the non-self cells.
Blood Typing
• Based on your specific blood type your body will also
have antibodies (a special type of white blood cell
destroys foreign antigens) floating in your blood that are
looking for antigens that do not match your special
combination.
• For example: if you have type A blood, you have
antigens on your cells that represent type A blood.
– You also have antibodies called Anti-B antibodies.
– These antibodies are looking for cells that have the B antigen
present on their cells, and if it recognizes them the antibody
sees those cells as foreign because they do not match your red
blood cells, so those antibodies will try to kill the cells.
Blood Types and Cross-Reactions
Blood Types and Cross-Reactions
• If your body reacts to foreign cells that do not match
yours the immune reaction that occurs is called
agglutination (which is clumping or clotting that
occurs in the body).
– It can be dangerous and cause death.
Blood Typing
• In addition to the blood types A, O, AB and B an
additional factor is taken into account called the Rh
factor.
– The Rh Factor, also called the D antigen determines
positive vs. negative blood types.
• For example someone that has both the A antigen and
the Rh antigen as an A+ blood type.
– If someone has the A and B antigens but no Rh antigen they
have an AB- blood type.
• Individuals that are Rh negative also have an extra
antibody present called the anti-Rh antibody that looks
for cells that have the Rh antigen.
Red Blood Cell Disorders
• Anemia: occurs when there is not enough RBC
to deliver oxygen to the body.
– May be due to:
• Low RBC count (like donating blood or loosing a lot of
blood)
• Abnormal hemoglobin
• Abnormal shape of cell
(like sickle cell anemia)