Leucocytes

Question 1

Which is the only complete cell found in the blood?

Answer 1

Leucocytes

Question 2

What is the normal count of leucocytes?

Answer 2

4000- 11000 per cubic micrometre of blood.

Question 3

How much volume of blood do Leucocytes make?

Answer 3

1%

Question 4

What are the two categories of leucocytes?

Answer 4

1. Granulocytes
2. Agranulocytes

Question 5

What are granulocytes?

Answer 5

1. Polymorphonuclear neutrophils
2. Polymorphonuclear Eosinophils
3. Polymorphonuclear basophils
   They are charecterised by the presence of granules containing proteins and enzymes.

Question 6

What is the main function of granulocytes?

Answer 6

They are involved in:
1. Phagocytosis
2. Inflammation
3. Allergic Reactions

Question 7

What is the lifespan of granulocytes?

Answer 7

In blood - 4-8 hours
In tissues- 4-5 days

Question 8

Why does the longevity of leucocytes increase in the tissues?

Answer 8

The WBCs uptake growth factors by expressing growth factor receptors on their surface in tissues.

Question 9

What are the physical charecteristrics of different granulocytes?

Answer 9

1. Neutrophils: 3-5 lobes of nucleus with pale red and blue coloured cytoplasm.
   10-12 micrometric in diameter.
2. Eosinophils: 2 lobes of nucleus (bilobed) with red colour cytoplasm.
   10-12 micrometre in diameter.
3. Basophils: No lobes of nucleus (S or U shaped) with purplish-black colour cytoplasm.
   8-10 micrometre in diameter.

Question 10

Why are neutrophils named so?

Answer 10

Neutrophils have granules that take up both acidic and basic dye. They re “neutral”.

Question 11

What do neutrophilic granules contain?

Answer 11

1. Peroxidases
2. Hydrolytic enzymes
3. Defensins (anti-biotic like proteins)

Question 12

What is the defense strategy of neutrophils?

Answer 12

1. Leucocytosis Increase in WBCs.
2. Margination
3. Diapedesis
4. Chemotaxis
5. Amoeboid Motion
6. Phagocytosis

Question 13

What is margination?

Answer 13

It is the attachment of neutrophils to the surface of endothelium to change it.

Question 14

What is diapedesis?

Answer 14

Margination loosens the intercellular bonds in the endothelium, causing neutrophils to move out. This is called diapedesis.

Question 15

What is chemotaxis?

Answer 15

It is the movement of a cell towards a chemical that is unknown to it.

Question 16

What are chemotaxic agents?

Answer 16

1. Bacterial and viral toxins.
2. Degenerative products of tissue inflammation.
3. Reaction products from activation of “complement complex”.
4. Reaction products from plasma clotting.

Question 17

How does neutrophil carry out phagocytosis?

Answer 17

It extends its pseudopodia to wards the bacteria or virus, engulfing it in a vacuole (phagosome).
It then releases hydrolytic enzymes and lysosymes to digest it.

Question 18

How many bacteria can 1 neutrophil phagocytise?

Answer 18

3 -20

Question 19

Why does an infection leave uS feeling weak?

Answer 19

Neutrophils perform phagocytosis through acidic hydrolysis which can kill normal cells. This collateral damage makes US feel weak after infections.

Question 20

What is the function of eosinophils?

Answer 20

1. Lead body’s reaction against parasatic worms.
2. Lessen the severity of allergic reactions by phagocytising allergy complexes.

Question 21

How do basophils function?

Answer 21

Behave like mast cells. Both get activated by IgE that binds to them and causes them to rupture. This releases chemicals such as:
1. Heparin
2. Seratonin
3. Histamine
4. Bradykinin
5. Lysosomal enzymes
This causes allergy reactions.

Question 22

What is the lifespan of agranulocytes?

Answer 22

Monocytes- 10-20 hours in blood.
Lymphocytes- Weeks or months depending on demand.

Question 23

What are the physical charecteristrics of agranulocytes?

Answer 23

1. Monocytes: Kidney shaped nucleus and abundant pale blue cytoplasm.
   12-20 micrometre in diameter.
2. Lymphocytes: large nucleus with a pale blue thin rim.
   6-9 micrometre or 10-14 micrometre in diameter.

Question 24

…….. are also called microphages.

Answer 24

Neutrophils

Question 24

What is the neutrophils and macrophage sequence of response during inflammation?

Answer 24

1.1st line of defense: Tissue macrophage 2.2nd line of defense: Neutrophil invasion (Neutrophilia). 3.3rd line of defense: Second macrophage invasion. 4.4th line of defense: Increase in production of granulocytes and monocytes by the bone marrow.