T1: Functions of Leukocytes

Question 1

What are leukocytes? What percentage of blood do they occupy? What is their structure? What is their function

Answer 1

• immune system cells circulating through the blood and lymphatic system
• 1% of blood volume
• have a nuclei
• protect the body against infectious diseases and foreign materials

Question 2

What are the agranular types of leukocytes?

Answer 2

lymphocyte
monocyte

Question 3

What are the granular types of leukocytes?

Answer 3

eosinophil
neutrophil
basophil

Question 4

What are the different types of white blood cells?

Answer 4

lymphocyte
monocyte
eosinophil
basophil
neutrophil

Question 5

What is the function of neutrophils?

Answer 5

• combat bacterial infections
• engulf and destroy bacteria

Question 6

What is the function of lymphocytes? What do they include?

Answer 6

include: B cells, T cells
- B cells: produce antibodies to neutralize pathogens
- T cells: cell-mediated immunity, target infected cells, coordinate immune responses

Question 7

What is the function of monocytes? What do they differenetiate into?

Answer 7

differentiate into: macrophages or dendritic cells
macrophages: engulf and destroy pathogens, cellular debris, and dead cells.
dendritic cells: present antigens to activate other immune cells

Question 8

What is the function of eosinophils?

Answer 8

• allergic reactions
• defence against paracytic infections
• release toxic substances to destroy paracytes
• modulate inflammation

Question 9

What is the function of basophils?

Answer 9

• allergic responses
• release of histamine (inflammation and allergic symptoms)

Question 10

What are the general functions of white blood cells?

Answer 10

• phagocytosis (neutrophils and monocytes)
• antibody production (B cells)
• cellular immunity (T cells)
• inflammatory response
• immune surveillance
• allergic response (eosinophils)
• histamine release (basophils)

Question 11

What is the most abundant type of white blood cells in mammals?

Answer 11

neutrophils

Question 12

Explain the structure of neutrophils.

Answer 12

• multilobed nucleus
• granular cytoplasm
• most abundant

Question 13

Explain the structure of monocytes.

Answer 13

• largest leukocytes

Question 14

What are the main types of phagocytes?

Answer 14

• monocytes
• macrophages
• neutrophils
• tissue dendritic cells
• mast cells

Question 15

Explain the phagocytosis mechanism.

Answer 15

1) bacterium becomes attached to pseudopodia (membrane envaginations).
2) bacterium is ingested, forming phagosome.
3) phagosome fuses with lysosome.
4) bacterium is killed and digested by lysosomal enzymes.
5) digestion products are released from the cell.

SEVERAL STAGES

Question 16

Where do monocytes develop? Where do monocytes reach maturity?
Explain their maturation process.

Answer 16

• develop in the bone marrow
• reach maturity in the blood

Monocytes leave the blood stream after 20-40h
travel to tissues and organs
monocyte –> macrophage/dendritic cells (depending on the recieved signals)

Question 17

What is a special role of neutrophils?

Answer 17

• release perforin, granzyme, proteases, and other chemicals
• cause cytotoxic damage to pathogens

Question 18

What cells differenciate into macrophages?

Answer 18

monocytes

Question 19

Do macrophages produce antibodies? What? What are antibodies?

Answer 19

Macrophages do NOT produce antibodies!
- antibodies are produced by B cells (lymphocytes)

Antibodies (proteins) recognise specific antigens on the surface of pathogens.

Question 20

What are the two white blood cell count disorders?

Answer 20

Leukocytosis: too many white blood cells (from stress, infection, inflammation or bone marrow disease)

Leukopenia: too little white blood cells = increase in risk of infection (from medical cinditions, viral infections and bone marrow disorders).