Transcript FORMATION OF WHITE BLOOD CELLS

FORMATION OF WHITE BLOOD
CELLS
Dr. B.L. Mtinangi.
Department of Physiology
School of Medicine, MUHAS
November, 2015
FORMATION OF WBC
As for the Rbc, the formation of
Wbc originates from the COMMON
PROGENITOR CELL ie
uncognisable cell which develop
to the UNCOMMITTED STERM
CELL and this changes to
COMMITTED STERM CELL
FORMATION OF WBC CONT.
Committed sterm cell can either develop
into:
• Myeloblast series or
• Monoblast or
• Lymphoblast series.
Myeloblast changes into Promyelocyte &
the Promyelocyte to Myelocyte which
will either develop into
• NEUTROPHIL or BASOPHIL or
EOSINOPHIL.
FORMATION OF WBC CONT.
Monoblast develop into:
• Monocyte in the circulating blood
• Tissue Macrophage ie the Monocyte
that has moved into various tissues.
Lymphoblast from Lymphogenous organs
develop into Prolymphocyte which will
then develop into:
• Large Lymphocyte &
• Small Lymphocyte
WBC CONT.
White blood cells are Leucocytes &
Macrophages that are involved in
the defence mechanisms against:
• Bacteria
• Viruses
• Fungus &
• Parasites
WBC CONT.
Mechanism of action of Wbc is either
• Phagocytic eg neutrophil, eosinophil,
basophil & monocytes OR
• Antibodies formation eg lymphocytes
Wbc are of two types:
• With granules (Granulocytes)
• Without granules (Agranulocytes)
Normal Wbc count ranges from 4000 to
11000/micro litre
WBC CONT.
Wbc with granules (granulocytes) are
• Neutrophils 40 – 70% (60%)
• Eosinophil
1 – 4%
(3%)
• Basophil
0 - 2%
(1%)
Wbc without granules (agranulocytes)
• Lymphocytes 20 – 45% (30%)
• Monocytes
4 - 8%
(6%)
NB. Platelets are sometimes grouped as
Wbc
FUNCTIONS OF WBC
Granulocytes and Monocytes are
for
• PHAGOCYTOSIS
Lymphocytes are for IMMUNITY ie
• Cell mediated immunity &
• Antibody formation
Platelets are for blood clotting
(COAGULATION) mechanisms
Type Of White Blood
Cells
% By Volume Of WBC
Description
Function
Neutrophils
60 – 70 %
Nucleus has many
interconnected lobes; blue
granules
Phagocytize and destory
bacteria; most numerous WBC
Eosinophils
2–4%
Nucleus has bilobed nuclei; red
or yellow granules containing
digestive enzymes
Play a role in ending allergic
reactions
<1%
Bilobed nuclei hidden by large
purple granules full of chemical
mediators of inflammation
Function in inflammation
medication; similar in function
to mast cells
20 – 25 %
Dense, purple staining, round
nucleus; little cytoplasm
the most important cells of the
immune system; effective in
fighting infectious organisms;
act against a specific foreign
molecule (antigen)
4–8%
Largest leukocyte; kidney
shaped nucleus
Transform into macrophages;
phagocytic cells
Basophils
Lymphocytes (B Cells
and T Cells)
Monocytes
WBC CHARACTERISTICS
Each Wbc has specific
distinguishing characteristics in
terms of:
• Cell size
• The shape of Nuclear
• Cytoplasmic content
• Type of granules &
• Phagocytic activity of the cell
LIFE SPAN OF WBC
The life span of the Wbc differs
depending on the type of Wbc:
• Granulocytes have a life span of 4 to 8
hrs in the circulation and 4 to 5 days in
tissues
• Monocytes have a short transit in
circulation then go to TISSUES as
Tissue macrophages
• Lymphocytes have a life span of about
100 to 300 days, tend to recirculate.
Some are known to have a life span of
7 years
MECHANISM OF CELL
PHAGOCYTOSIS
• Margination ie lining of cells(Wbc) on
the capillaries due to bacteria products
or toxins
• Diapedesis ie squeezing through small
pores in blood capillaries
• Migration ie ameboid or psedopodia
motion esp Neutrophils & macrophages
• Chemotaxis ie movements due to
bacteria toxins & inflammation.
All cause a directional migration of
NEUTROPHIL & MACROPHAGES to the
site of injury or infection
PHAGOCYTOSIS CONT.
The process of phagocytosis:
• Bacteria are ENGULFED by
Pseudopodia & Fusion
• Bacteria then lies within a cel l
vacuole with phagosome
• Lysosomal or digestive enzymes
are secreted into phagosome
causing
• Degranulation & Lysis of the
bacteria leading to DEATH
BREAK