This document discusses the composition and functions of white blood cells (leukocytes), which are essential for the body's immune response. It categorizes leukocytes into granulocytes and agranulocytes, detailing their types, lifespans, and roles in phagocytosis and antibody formation. Additionally, it covers conditions related to abnormal white blood cell counts, such as leukocytopenia and leukemia.

1. WHITE BLOOD CELLS
Maniratan Vardhan
M.Sc. Zoology Final Year

2. BLOOD
• Blood is a specialized connective tissue in which there is a liquid
intercellular substance known as plasma and formed elements,
the red blood cells, white blood cells and the platelets
suspended in the plasma.

4. LEUKOCYTES
Our bodies have a special system for combating the
different infectious and toxic agents. This system is
composed of blood leukocytes (white blood cells) and
tissue cells derived from leukocytes. These cells work
together in two ways to prevent disease:
(1) by actually destroying invading bacteria or viruses
by phagocytosis .
(2) by forming antibodies and sensitized
lymphocytes, which may destroy or inactivate the
invader.

5. The leukocytes/leucocytes,
also called white blood cells, are
the mobile units of the body’s
protective system. They are
formed partially in the bone
marrow (granulocytes and
monocytes and a few
lymphocytes) and partially in
the lymph tissue(lymphocytes
and plasma cells). After
formation, they are transported
in the blood to different parts of
the body where they are
needed.

6. Broadly we can divide leukocytes into two
categories:-
• Granulocytes :- White blood cells who consist
granular cytoplasm. They have multiple lobes and
are also known as polymorphonuclear leukocytes.
They are neutrophils, eosinophils and basophils.
• Agranulocytes :-These are the type of white blood
cells without the granules. They have only one lobe
and are known as mononuclear leukocytes due to
the presence of just one nucleus. They are
lymphocytes and monocytes.

8. The life of the granulocytes after being released from the
bone marrow is normally 4 to 8 hours circulating in the blood
and another 4 to 5 days in tissues where they are needed.
The monocytes also have a short transit time, 10 to 20 hours
in the blood, before wandering through the capillary
membranes into the tissues.
Life Span of the White Blood Cells

9. • Determination of the percentage of different
varieties of leukocytes is known as
DIFFERENTIAL LEUKOCYTE COUNT.

10. • The process of generating white blood cells
(LEUKOCYTES) from the pluripotent
HEMATOPOIETIC STEM CELLS of the BONE
MARROW. There are two significant pathways to
generate various types of leukocytes:
MYELOPOIESIS, in which leukocytes in the blood are
derived from MYELOID STEM CELLS, and
LYMPHOPOIESIS, in which leukocytes of the
lymphatic system (LYMPHOCYTES) are generated
from lymphoid stem cells.
Leukopoiesis

12. Neutrophils
•Most abundant type of WBC i.e. about 60-70%.
•Multilobed nucleus with short life span .
•Cytoplasm is with fine granules which stain with both acidic and
basic dyes so appear violet in colour.
•They are the Soldiers of Blood Stream.
•They show diapedesis and does phagocytosis.
•These have Drum stick (a type of barr body ) in females , so also
help in sex determination.

13. Basophils
• Stained with basic dyes like methylene blue.
• They are least in number i.e. about less than 1%.
• Also known as Mast cells of blood because they secrete
heparin, histamine and serotonin.
• S- shaped 2-3 lobed nucleus.

14. Acidophils or Eosinophils
• Cytoplasmic granules are coarse and take acidic dyes like eosin ,
so also called eosinophils.
• Bilobed nucleus.
• Constitute about 2-4% TLC.
• Their number increase in allergic diseases, such as asthma and in
parasitic infections.
• Increase count is known as EOSINOPHILIA.
• Also help in healing of wounds as destroy toxins of the microbes.
• Non phagocytic in nature.

15. Monocytes
• Largest leucocytes.
• Nucleus is kidney shaped.
• They are about 4-7%.
• Known as Macropoliceman of body.
• Have pseudopodia that is why they show diapedesis
and does phagocytosis.
• Also form second line of defence.

16. Lymphocytes
• Second most abundant leucocytes i.e. about 30-40%.
• Nucleus is large and rounded so that the cytoplasm
forms a thin peripheral layer.
• Primary function is to produce antibodies and
opsonins.
• These are of two types:-
1. B- lymphocytes
2. T- lymphocytes

17. • B-lymphocytes :---
These are mature in bone marrow and make antibodies
i.e. forms humoral immune system to fight infections and
foreign proteins in the body.
• T- lymphocytes :---
These are mature in Thymus gland and related to cell
mediated immune system and fight foreign cells in body.

18. Functions of WBC
1.Phagocytosis:- The neutrophil polymorphonuclear
leucocytes and the monocytes engulf foreign particles and
bacteria, and generally digest them. This process is called
phagocytosis.
2. Formation of Antibodies by lymphocytes cells.
3. Secretion of heparin which prevents intravascular clotting.
4. Secretion of anti-inflammatory factor histamine which
defend against allergic conditions.

19. • Leukocytopenia – abnormal decrease of WBC count.
• Leukocytosis – abnormal increase of WBC count.
• Leukemia – also known as Blood Cancer.
Abnormal increase in WBC count due to uncontrolled
division.
• Agranulocytosis – great fall in the number of
granulocytes.
Abnormal Variation in White blood
corpuscles count

20. THANK
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