1. What are White Blood
Cells (WBCs)?
- Also
called Leukocytes (Leuko = white, cyte = cell).
- They are colorless,
nucleated cells of blood.
- Main role:
Defend the body against infections, allergens, and foreign bodies.
- WBCs are
part of the immune system.
2. Normal WBC Count
- Total
count: 4,000 – 11,000 / mm³ of blood
- Life span: Few hours
to few days (depends on type)
- Site of
production: Bone marrow and lymphoid organs
3. Types of WBCs
Divided into 2 main types:
|
Category |
Type |
Mnemonic |
|
Granulocytes |
Neutrophils, Eosinophils, Basophils |
“NEB” |
|
Agranulocytes |
Lymphocytes, Monocytes |
“LM” |
4. Granulocytes –
Contain granules in cytoplasm
a. Neutrophils
- Most
abundant (60–70%)
- Function: Fight
bacterial infections (via phagocytosis)
- 1st line
of defense
Mnemonic: “NEUTRO = NEUtralize Bacteria”
b. Eosinophils
- 1–4% of
WBCs
- Function:
Fight parasites, allergies (release antihistamines)
Mnemonic: “E-O-sinophil = Eww Organisms (parasites)”
c. Basophils
- Least in
number (<1%)
- Function:
Secrete histamine (causes allergy & inflammation)
Mnemonic: “Baso = B for Bee sting reaction”
5. Agranulocytes – No
granules, large nucleus
a. Lymphocytes
- 20–25% of
WBCs
- T cells (kill
infected cells) and B cells (make antibodies)
Mnemonic: “Lympho = Long-term immunity”
b. Monocytes
- 3–8% of
WBCs
- Largest
WBC, becomes macrophage in tissues
- Function: Phagocytosis
of dead cells, bacteria
Mnemonic: “Mono = Monster eater (Macrophage)”
6. Functions of WBCs
Mnemonic: “FIGHTS”
|
Letter |
Function |
|
F |
Fight infections (neutrophils) |
|
I |
Immunity (lymphocytes) |
|
G |
Gobble pathogens (monocytes) |
|
H |
Handle allergies (eosinophils) |
|
T |
Tissue defense (macrophages) |
|
S |
Secrete histamine (basophils) |
7. Abnormal WBC
Conditions
|
Condition |
Description |
|
Leukocytosis |
↑ WBCs (Infection, inflammation) |
|
Leukopenia |
↓ WBCs (Viral infection, bone marrow issues) |
|
Leukemia |
Cancer of WBCs (uncontrolled growth) |
8. Summary Table
|
WBC Type |
% in Blood |
Function |
Mnemonic |
|
Neutrophils |
60–70% |
Bacterial defense |
NEUtralizer |
|
Eosinophils |
1–4% |
Allergies, parasites |
Eww Organisms |
|
Basophils |
<1% |
Allergic response |
B for Bee sting |
|
Lymphocytes |
20–25% |
Antibodies & immunity |
Long-term immunity |
|
Monocytes |
3–8% |
Phagocytosis in tissues |
MONO = Macrophage |
FAQs – Frequently Asked
Questions
Q1. What are white
blood cells?
Ans: WBCs (Leukocytes) are immune cells in blood that protect the body from
infection and foreign substances.
Q2. What is the normal
WBC count?
Ans: 4,000 – 11,000 / mm³ of blood.
Q3. Which is the
largest WBC?
Ans: Monocyte – It becomes a macrophage in tissues.
Q4. Which WBCs are
involved in allergy?
Ans: Eosinophils and Basophils.
Q5. What are the two
main types of WBCs?
Ans:
- Granulocytes –
Neutrophils, Eosinophils, Basophils
- Agranulocytes –
Lymphocytes, Monocytes
Q6. What is
leukocytosis?
Ans: Increase in WBC count, usually seen in infections or inflammation.
Q7. Which WBC makes
antibodies?
Ans: B-lymphocytes.
