12 Questions
Which of the following is true about the complement system?
It marks pathogens for destruction by phagocytes.
What is the function of some small fragments of complement proteins?
Act as chemoattractants to recruit more phagocytes and activate them.
How is the complement system activated?
Through a triggered-enzyme cascade.
What is the role of complement proteins in opsonization?
They bind covalently to pathogens, marking them for destruction by phagocytes.
Which of the following is a function of terminal complement proteins?
Creating pores in bacterial membranes
Which protein mediates the ingestion of complement-tagged pathogens by phagocytes?
CR1
What is the main function of small fragments of complement?
Stimulate increased blood flow and vascular permeability
What is the function of cytokines?
Induce responses through binding specific receptors
What is the main function of chemokines?
Induce directed chemotaxis in nearby responsive cells
What is the role of complement in the immune response to bacteria?
Enabling the engulfing of bacteria and recruitment of cells to the site of infection
What is the outcome of complement activation?
Increased blood flow and vascular permeability
Which receptor is mainly involved in the chemoattraction of monocyte/macrophage and neutrophils?
CCR
Study Notes
Complement System Overview
- The complement system is a part of the immune response to bacteria.
Activation and Functions
- The complement system is activated via three pathways: classical, alternative, and lectin.
- Some small fragments of complement proteins have anaphylatoxin function, which increases blood vessel permeability and attracts immune cells.
- Complement proteins play a role in opsonization, marking pathogens for destruction by phagocytes.
- Terminal complement proteins create a membrane attack complex, which forms a pore in the pathogen's membrane, leading to lysis.
Phagocytosis and Chemotaxis
- Complement protein C3b mediates the ingestion of complement-tagged pathogens by phagocytes.
- Small fragments of complement, such as C3a and C5a, have a main function of attracting immune cells to the site of infection.
- Cytokines, including chemokines, have a function of recruiting immune cells to the site of infection.
- Chemokines specifically have a main function of attracting immune cells, including monocyte/macrophage and neutrophils, to the site of infection.
- The receptor mainly involved in the chemoattraction of monocyte/macrophage and neutrophils is CCR2.
Outcome of Complement Activation
- The outcome of complement activation is the destruction of pathogens, including bacteria, through various mechanisms such as opsonization and membrane attack complex.
Test your knowledge of innate immunity in immunology with this quiz. Explore topics such as phagocytosis by macrophages, pattern recognition, release of cytokines and chemokines, and the activation of complement. This quiz covers essential concepts in understanding the body's initial response to pathogens.
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