T1: Functions of Leukocytes Flashcards
What are leukocytes? What percentage of blood do they occupy? What is their structure? What is their function
- 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
What are the agranular types of leukocytes?
lymphocyte
monocyte
What are the granular types of leukocytes?
eosinophil
neutrophil
basophil
What are the different types of white blood cells?
lymphocyte
monocyte
eosinophil
basophil
neutrophil
What is the function of neutrophils?
- combat bacterial infections
- engulf and destroy bacteria
What is the function of lymphocytes? What do they include?
include: B cells, T cells
- B cells: produce antibodies to neutralize pathogens
- T cells: cell-mediated immunity, target infected cells, coordinate immune responses
What is the function of monocytes? What do they differenetiate into?
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
What is the function of eosinophils?
- allergic reactions
- defence against paracytic infections
- release toxic substances to destroy paracytes
- modulate inflammation
What is the function of basophils?
- allergic responses
- release of histamine (inflammation and allergic symptoms)
What are the general functions of white blood cells?
- phagocytosis (neutrophils and monocytes)
- antibody production (B cells)
- cellular immunity (T cells)
- inflammatory response
- immune surveillance
- allergic response (eosinophils)
- histamine release (basophils)
What is the most abundant type of white blood cells in mammals?
neutrophils
Explain the structure of neutrophils.
- multilobed nucleus
- granular cytoplasm
- most abundant
Explain the structure of monocytes.
- largest leukocytes
What are the main types of phagocytes?
- monocytes
- macrophages
- neutrophils
- tissue dendritic cells
- mast cells
Explain the phagocytosis mechanism.
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
Where do monocytes develop? Where do monocytes reach maturity?
Explain their maturation process.
- 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)
What is a special role of neutrophils?
- release perforin, granzyme, proteases, and other chemicals
- cause cytotoxic damage to pathogens
What cells differenciate into macrophages?
monocytes
Do macrophages produce antibodies? What? What are antibodies?
Macrophages do NOT produce antibodies!
- antibodies are produced by B cells (lymphocytes)
Antibodies (proteins) recognise specific antigens on the surface of pathogens.
What are the two white blood cell count disorders?
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).
