HEMATOPOIETIC SYSTEM I:
Margaret Uthman, MD
Gartner and Hiatt, pages 89-101; Klein and McKenzie, pp155-181
Describe the composition of normal peripheral blood, including the relative quantities of the blood
Identify normal peripheral blood cells.
Describe the function and "life cycle" of normal peripheral blood cells.
: Erythrocytes, reticulocytes, neutrophils, eosinophils, basophils, monocytes, lymphocytes and
Blood is a fluid connective tissue constituting about 7% of our total body weight (about 5 liters in the
The primary components are:
: The liquid in which peripheral blood cells are suspended. Composed of water, electrolytes
such as Na
and Cl, (0.9%), 7% plasma proteins (such as albumin, fibrinogen, globulins), hormones,
fats, amino acids, vitamins carbohydrates, lipoproteins as well as other substances.
plasma volume is 40 ml/kg of body weight.
Formed Elements (blood cells):
Erythrocytes (red blood cells or rbc):
occupy about 40-45% of the total blood volume or 30
ml/kg body weight.
Leukocytes (white blood cells or wbc) and Platelets:
together make up about 1-2% of the
total blood volume.
Freshly drawn blood is a red fluid (specific gravity of 1.052-1.064).
It forms a jelly-like mass if
allowed to clot.
The clot is formed by the conversion of fibrinogen to fibrin which forms a
meshwork that entraps the formed elements.
If the gel is centrifuged, cell free serum can be
If an anticoagulant is added, blood can be sedimented into three distinct layers due to
different densities of elements: rbc > wbc > plasma.
The lowermost layer (45% of the blood
volume) consists of erythrocytes.
Above this region is a grayish white layer (buffy coat) which
represents the platelets, lymphocytes and granulocytes (about 1-2% volume).
Plasma is the top
II. Morphology and Function of the Blood Cells
A. Erythrocytes (mature red blood cells)
The mature human erythrocyte measures about 7-8
m in diameter and appears as an anucleate,
In addition to the nucleus, the mature erythrocyte also loses its Golgi