lec 10: Functions of WBCs Flashcards
White blood cells are
large, nucleated, motile cells
Total leukocytic count range is between………….
4000-11000 WBC /mm³
Neutrophils
(60-70%).
Eosinophils
(1-4%).
Basophils
(0.25-0.5% )
Lymphocytes
(25-33 %).
Monocytes
(2-6%).
It is the movement of leukocytes which starts by protrusion of
pseudopodium from one end, then movement of the remainder of
the cell towards this pseudopodium.
Ameboid motion
Chemotaxis
A. Some of the bacterial or viral toxins.
B. Degenerative products of the inflamed tissues.
C. Leukotrienes and polypeptides from WBCs (lymphocytes,
mast cells and basophils).
D. Several components of the “complement complex (C5a).
Diapedesis, amoeboid movement, chemotaxis and phagocytosis are evident in …………………and……………
NEUTROPHILS and MONOCYTES.
Opsonization: It is the coating of the foreigner
(bacteria) by opsonins like
IGg , C3b
……………from neutrophils protrude around the bacteria and fuse to form a phagosome
Pseudopodia
the most numerous white blood cell in the circulation
Neutrophils
increase in infection with pyogenic bacteria.
Neutrophils
Average half life of the inactivated neutrophil in the circulation is
6 hours
A single neutrophil can usually phagocytize ……………….. before the neutrophil itself becomes inactivated and dies
3 to 20 bacteria
neutrophil can synthesize toxic oxygen metabolites like …………………………………………..
superoxide radical (O‾₂) and hydrogen peroxide (H₂O₂) and hypochlorous acid (HOCl).
……………….exhibit diapedesis , chemotaxis and weak phagocytosis
Mature eosinophils
the least common of granulocytes in peripheral blood
Basophils
do not exhibit phagocytosis
Basophils
They bear membrane receptors to IgE and are involved in allergic reactions
Basophils
……………….. increase in parasitic and allergic conditions
Eosinophils
functions of Basophils
- Release of HISTAMINE and other inflammatory mediators when activated . These mediators initiate INFLAMMATION
- Release of HEPARIN which prevents blood coagulation by acting as a cofactor for anti-thrombin III. Heparin may also exert anti-inflammatory effects
Basophils are involved in…………………….which range from mild urticaria to severe anaphylactic shock.
type- I HYPERSENSITIVITY
Ig E (the antibody that causes allergic reactions) become attached to basophlis and mast cells. Binding of IgE with its specific allergen→ to rupture of cytoplasmic granules of MAST CELLS and BASOPHILS with subsequent release of HEPARIN and ALLERGIC MEDIATORS which include:
- Histamine
- SRSA (Slow reacting substance of anaphylaxis), known now as LEUKOTRIENES
- bradykinin
- Lysosomal enzymes
- Serotonin.
the largest blood cells
Monocytes
Its cytoplasm is rich in lysosomes and they are professional phagocytic cells.
Monocytes
They circulate in the blood for 72 hours then migrate to the tissues where they change into tissue macrophages (large phagocytic cells), whose life span is unknown
Monocytes
Tissue macrophages constitute the tissue macrophage system (Reticulo-endothelial
system) which include :-
- Kupffer cells in the liver.
- Pulmonary alveolar macrophages (PAM).
- Microglia in the brain.
- Bone osteoclasts.
………………………….form the core of immune system in humans. They provide defense against targets to which they are programmed
Lymphocytes
About………………………of body lymphocytes are found in the peripheral blood and the rest are in the lymphoid tissues.
2%
…………………..are responsible for humoral immunity. , produces immunoglobulins .
B-lymphocytes
……………….. are responsible for cell mediated immunity . They attack and kill virus- infected cells as
well as malignant cells . They also facilitate antibody
production by B-cells.
T-lymphocytes
WBCs are activated by …………………………..
contact with the organism or its toxin.
• Activated WBCs show …………………………
increased motor activity, phagocytosis and degranulation.
The…………….. is stimulated by different cytokines to increase leukopoiesis.
bone marrow
• Once the organism is eradicated, Immune cells undergo apoptosis except for………………
memory cells.
prevent overactivity of the immune system
T-regulatory cells
