The Cardiovascular system
• Components:
– Blood
– Heart
– Blood vessels
THE BLOOD
• Blood Components
– Plasma – 55% of blood
– Water – 91%
– Proteins (most abundant molecules):
• Albumins – osmotic pressure - buffer
• Globulins – immunity
• Fibrin – blood clots
– Electrolytes: Na, Ca, Cl, Mg
– Nutrients, wastes
Formed elements
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Red blood cells
White blood cells
Platelets
All formed in the bone marrow
Within the bone marrow, all blood cells
originate from a single type of
unspecialized cell called a stem cell.
• When a stem cell divides, it first becomes
an immature red blood cell, white blood
cell, or platelet-producing cell.
• The immature cell then divides, matures
further, and ultimately becomes a mature
blood cell.
• The rate of blood cell production is
controlled by the body’s needs.
• Normal blood cells last for a limited time
(ranging from a few hours to a few days
for white blood cells, to about 10 days for
platelets, to about 120 days of RBC’s )
• Therefore, these cells must be replaced
constantly.
• Certain conditions may trigger additional
production of blood cells.
• When oxygen content of body tissues
is low or the number of red blood cells
decreases, the kidney’s produce and
release erythropoietin, a hormone that
stimulates the bone marrow to produce
more red blood cells.
• More WBC’s are produced and released in
response to infection.
• It produces and releases more platelets in
response to bleeding.
• Red Blood Cells
– Carry oxygen gas to body tissues
– Filled with hemoglobin
• Four subunits; each has heme + iron
• Heme binds and releases oxygen gas
• Strong affinity for carbon monoxide
– Life cycle of red blood cell
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Born in the bone marrow
Synthesizes hemoglobin, matures
Goes into circulation
Physical wear and tear accumulates
• After about 120 days, sticks in liver or
spleen
• Cell is phagocytised by macrophages
• Hemoglobin protein is digested
• Heme broken down to bilirubin – build up =
jaundice
• Iron is recycled to new hemoglobin
• Hormone erythropoietin controls rate of
red cell production in the bone marrow
• White blood cells
– 4,000 – 11,000 per cu. mm of blood
– Clean up wastes and debri – phagocytosis
(cell eating)
– Protect against disease (immune system)
– There are 5 different kinds of WBC’s
• Neutrophils: 60-70% - function
phagocytosis.
• Eosinophils: 2-4% - Destroy parasitic
worms. Combat effects in allergic
responses caused by histamine.
• Basophils: 0.5 – 1% - Produce heparin
and histamine.
• Lymphocytes: 25% - round nucleus, small
amount of cytoplasm – mediate immune
response – B cells form antibodies – T
cells attack invaders.
• Monocytes: largest WBC – kidney shaped
nucleus – phagocytosis
• Platelets or thrombocytes: Cell fragments
(megakaryocyte) circulating in the blood –
involved in the cellular mechanisms of
hemostasis or blood clotting
• Dysfunction or low levels of platelets
predisposes to bleeding.
• High levels usually asymptomatic, but may
increase the risk of thrombosis - clotting
Blood Types
• What are the different blood groups?
• The differences in human blood are due to the
presence or absence of certain carbohydrate or
protein molecules called anigens and antibodies.
The antigens are located on the surface of the
RBC’s and the antibodies are in the plasma.
Individuals have different types of combinations
of these molecules. The blood group you belong
to depends on what you have inherited by your
parents.
• ABO and Rh systems are the most
important ones used for blood transfusions
• Not all blood groups are compatible with
eachother.
• Mixing incompatible blood groups leads to
blood clumping or agglutination, which is
dangerous for individuals and can be fatal.
• ABO blood grouping system
• Blood group A
– If you belong to the blood group A, you have A
antigens on the surface of your RBC’s and B
antibodies in your plasma.
• Blood group B
– If you belong to the blood group B, you have B
antigens on the surface of your RBC’s and A
antibodies in your plasma.
• Blood group AB
– If you belong to the blood group AB, you have both A
and B antigens on the surface of your RBC’s and no A
or B antibodies at all in your blood plasma
• Blood group O
– If you belong to the blood group O (null), you
have neither A nor B antigens on the surface
of your RBC’s but you have both A and B
antibodies in your plasma.
Rh grouping
• Many people also have an Rh factor on their
RBC’s surface. This is also an antigen.
• Those who have it are called Rh+. Those who
do not are called Rh-.
• A person with Rh- blood does NOT have Rh
antibodies in the plasma. But a person with Rhblood CAN DEVELOP Rh antibodies in the
plasma if they receive Rh+ blood in a tranfusion.
• A person with Rh+ blood can receive blood from
a person with Rh- blood without any problems.
Hemolytic Disease - Anemia
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Reduction in RBC population
Diagnosed by hematocrit
Sickle cell anemia
Malaria
Leukemia
• Types of cnacer of the bone marrow
• White blood cells abnormal
• Risk factors include exposure to ionizing
radiation and carcinogens
• Acute and chronic
• Myeloid and lymphoid
Carbon Monoxide Poisoning
• CO is odorless
• Bonds much stronger to hemoglobin
molecule than oxygen
• Fumes from burning fuels primary cause
• Can be treated if detected early
Blood Clotting
• When a blood vessel is damaged, clot
plugs hole
– Damaged cells release chemical signals
– Platelets collect at site of damage
– Enzyme cascade produces fibrin (protein
strands that form a web)
– Clot is formed
• Hemophilia: genetic deficiency in clotting
factor