Podcast
Questions and Answers
What is the main mechanism by which leukocytes become activated to perform their functions?
What is the main mechanism by which leukocytes become activated to perform their functions?
Which type of leukocyte is described as 'rapid responders' and 'short-lived'?
Which type of leukocyte is described as 'rapid responders' and 'short-lived'?
Which receptors are responsible for binding low-density lipoprotein particles and a variety of microbes?
Which receptors are responsible for binding low-density lipoprotein particles and a variety of microbes?
What is the major functional activity of macrophages that requires transcriptional activation of cytokine genes?
What is the major functional activity of macrophages that requires transcriptional activation of cytokine genes?
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What is the enzyme present in azurophilic granules of neutrophils that is involved in the production of reactive oxygen species (ROS) during phagocytosis?
What is the enzyme present in azurophilic granules of neutrophils that is involved in the production of reactive oxygen species (ROS) during phagocytosis?
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Which type of immune cells contain granules packed with enzymes and antimicrobial proteins that degrade microbes and dead tissue?
Which type of immune cells contain granules packed with enzymes and antimicrobial proteins that degrade microbes and dead tissue?
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What is the main function of chemotaxis in acute inflammation?
What is the main function of chemotaxis in acute inflammation?
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Which of the following is NOT a chemotactic factor in leukocyte recruitment?
Which of the following is NOT a chemotactic factor in leukocyte recruitment?
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What is the key process that occurs after leukocytes firmly adhere to the endothelium during leukocyte recruitment?
What is the key process that occurs after leukocytes firmly adhere to the endothelium during leukocyte recruitment?
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In leukocyte cellular events, what is the primary purpose of phagocytosis and clearance of offending agents?
In leukocyte cellular events, what is the primary purpose of phagocytosis and clearance of offending agents?
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Study Notes
- Intracellular destruction of microbes and debris is carried out by phagocytic leukocytes, including neutrophils and macrophages.
- Leukocytes are activated by microbes, necrotic debris, and chemical mediators.
- Neutrophils are rapid responders, short-lived cells that primarily use degranulation and enzymatic activity in response to stimuli.
- Macrophages are slower, longer-lived cells that often require new gene transcription for their responses.
- Phagocytic cells, such as neutrophils and macrophages, have receptors that bind to microbes and ingested material, facilitating phagocytosis.
- Phagocytosis involves the recognition and attachment of particles to phagocyte receptors, extension of cytoplasm around the particle, and the formation of a phagosome.
- Inside the phagosome, microbes and ingested material are killed and destroyed using reactive oxygen species (ROS), reactive nitrogen species (mainly derived from nitric oxide), and lysosomal enzymes.
- Neutrophils and monocytes contain granules packed with enzymes and anti-microbial proteins, which are used to degrade microbes and dead tissue.
- Leukocyte recruitment to the site of injury or infection is facilitated by chemotaxis, which involves the movement of leukocytes along a chemical gradient towards the site of injury.
- Chemotactic factors include endogenous factors such as complement system components, arachidonic acid metabolites, and cytokines, as well as exogenous factors such as bacterial products.
- The mechanism of chemotaxis involves the binding of chemoattractants to G protein-coupled receptors on the surface of leukocytes, the initiation of signals, and the activation of second messengers, leading to the polymerization of actin and myosin filaments and the extension of filopodia.
- Leukocytes extend filopodia and move towards the injury in the direction of locally produced chemotractants.
- Phagocytosis and the clearance of offending agents are two key cellular events in acute inflammation.
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Description
Test your knowledge on leukocyte activation and phagocytic leukocytes. Learn about recognition of microbes, dead cells, and the activation of leukocytes by different stimuli. Explore the functions of neutrophils and macrophages in the immune response.
