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Blood
• Connective tissue
• Average adult has ~ 5 L
• Made up of formed elements and plasma
Formed elements
• Red blood cells (erythrocytes)
• White blood cells (leukocytes)
• Platelets (thromobocytes)
Plasma
• Makes up about 55% of the blood volume
• Composed of about 92% water
• Plasma proteins
– Albumin
– Globulin: antibodies of immunity, transport of
lipids, fat soluble vitamins
– Fibrinogen—blood clotting mechanism
– Enzymes and hormones
Plasma cont
• Nutrients and gases:
– Amino acids, sugars, lipids such as
cholesterol and triglycerides
– Oxygen and Carbon dioxide
Plasma cont
• Non-protein nitrogenous substances such
as urea and uric acids
• Electrolytes such as sodium, potassium,
bicarbonate
RBC
• Structure: biconcave disc—shape
increases surface area
• Have no nucleus when mature
• Are about 1/3 hemoglobin—O2 carrying
protein
RBC numbers
• Normal male
• Normal female
~4.6-6.2 million/cc
~4.2-5.4 million/cc
• Hematocrit--% of blood volume that is red
cells—normal is around 45% for males, a
little lower for females
• Hematocrit is closely related to oxygen
carrying capacity
RBC production
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Hematopoesis
Occurs in adults in red bone marrow
Average life span of rbc is about 120 days
Replacement is continuous—homeostatic
Affected by dietary factors—must have
sufficient Vitamin B12, folic acid and iron
RBC production
• Triggered by oxygen deficiency
• Hormone erythropoetin goes to bone
marrow and triggers production of rbcs
• High altitude athletic training
RBC destruction
• RBCs are damaged over time and rupture
• They are phagocytized and the
hemoglobin is broken down into heme and
globin (protein)
• Heme is broken down into iron (reused to
make more rbcs) and a substance called
bilirubin which is excreted as bile
Anemia
• Defined as lack of rbcs or oxygen carrying
capacity of rbcs
• Causes
– Too few rbcs being produced (bone marrow
problem)
– Increased destruction (sickle cell)
– Loss of blood
– Too little iron (small, pale rbcs)
Sickle cell anemia
Sickle cell anemia cont
• Cells are misshapen and do not flow
through the vessels easily
• Increased destruction of rbcs
• Anemia, microclots
• Recessive inherited disorder
WBCs
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Function in disease control
Normal value is ~4,000-11,000/cc
Produced in bone marrow
Have a nucleus
5 types totaling 100%
Granulocytes
• Live ~ 12 hours
• Divided into 3 categories
– Neutrophils ~40-70%
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Fine granules in nucleus
Nucleus is lobed
Phagocytic
Increased numbers in bacterial infections and
burns
• Eosinophils ~ 1-4%
– Deep red granules
– Increased in allergy, parasitic infections
• Basophils ~ 0-1%
– Dark blue granules
– Granules contain histamine which is a
vasodilator—increases blood flow to damaged
tissues
Monocytes
• Monocytes ~ 4-8%
– large kidney shaped nucleus
– Grayish-blue cytoplasm with no granules
– Live for months
– Phagocytic—clean up crew
– Increased in chronic infections
Lymphocytes
• Lymphocytes ~ 20-45%
– Small amount of cytoplasm with larger dark
blue nucleus
– B lymphs—produce antibodies
– T lymphs—fight viruses, tumors, active in graft
rejection and activate B lymphs
– Live for years
Platelets
• Not a complete cell
– Irregular shaped pieces of cell
– Produced in bone marrow
• Normal value ~250,000-500,000/cc
• Part of the clotting mechanism—cling
together to provide a plug at the site of a
broken or torn blood vessel and initiate the
clotting process