HUMAN MEDICAL BIOLOGY, ANATOMY, PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedoniuk 2010
ANATOMY, PHYSIOLOGY, PATHOLOGY
CHAPTER 4. BLOOD SYSTEM
PROTECTIVE FUNCTIONS OF BLOOD
1. CHARACTERISTICS OF LEUKOCYTES
Leukocytes, or white Blood Cells, are complete nucleated cells containing a Nucleus and other cellular structures. Unlike erythrocytes, they are capable of amoeboid movement, which enables them to leave the bloodstream and perform their Functions within the Connective Tissue of Organs. Leukocytes are formed in the Cytology/practical/86.html">Red Bone Marrow, while their maturation takes place in the Lymph Nodes AND Spleen. Their lifespan is 8–12 days.
The blood of an adult human contains (4-9) · 102 л-2 of leukocytes per liter. An increase in leukocyte count above 9 · 102 л-2 is referred to as leukocytosis, whereas a decrease below 4 · 102 л-2 is termed leukopenia.
Leukocytosis is classified into physiological (reductive/redistributive) and pathological. Physiological leukocytosis may occur during intense physical exertion (myogenic leukocytosis) or following a heavy meal (digestive leukocytosis). The leukocytosis observed in newborns—up to (10-30) · 102 л-2—is also considered physiological.
Pathological leukocytosis develops in response to inflammatory and infectious diseases. Leukopenia is observed exclusively under pathological conditions and serves as a constant symptom of radiation sickness.
Based on the cytoplastic characteristics, leukocytes are divided into two main groups: granular (granulocytes) and agranular (agranulocytes). Granulocytes include neutrophils (metamyelocytes, band, and segmented neutrophils), eosinophils, and basophils. Agranulocytes comprise lymphocytes and monocytes.
The percentage ratio of individual leukocyte types is known as the leukocyte differential count (differential WHITE BLOOD Cell count).
Certain diseases induce Changes in the proportions of specific leukocyte forms; therefore, determining the differential white blood cell count is of paramount clinical importance.
Lymphocytes are the smallest leukocytes (6-14 µm) with agranular Cytoplasm and a round nucleus that occupies nearly the entire cell.
Monocytes are the largest leukocytes (13-25 µm), also possessing agranular cytoplasm and a Kidney- or bean-shaped nucleus.
Granulocytes stain with different Dyes: neutrophils take up neutral stains, eosinophils acidic stains, and basophils basic stains, which accounts for their distinct coloration in blood smears. Depending on their maturity level, neutrophils are subdivided into band and segmented forms (along with young/metamyelocyte forms). Young neutrophils have an oval nucleus, band neutrophils have a rod-shaped nucleus, and segmented neutrophils possess nuclei consisting of several distinct segments.
Class="center">Table 4.1
Leukocyte differential count
Type of leukocyte |
Granulocytes |
Agranulocytes |
|||||
neutrophils |
eosinophils |
basophils |
lymphocytes |
monocytes |
|||
metamyelocytes /young/ |
band |
segmented |
|||||
Traditional units, % |
0-1 |
1-6 |
47-72 |
0,5-5,0 |
0-1 |
18-37 |
3-11 |
SI units: - conventional |
0-0,01 |
0,01-0,06 |
0,47-0,72 |
0,005-0,050 |
0-0,01 |
0,18-0,37 |
0,03-0,11 |
Absolute |
0-0,06 |
0,06-0,36 |
2,82-4,32 |
0,03-0,30 |
0-0,06 |
1,08-2,22 |
0,18-0,66 |
Last update: 08/08/2026
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