innate immune system Flashcards
(24 cards)
What happens when pathogens overcome external barriers?
They are engulfed by phagocytic cells that detect them using various receptors.
What are Toll-like receptors (TLRs)?
Receptors on phagocytic cells that recognize pathogen-associated molecular patterns not found in vertebrates.
What does TLR3 recognize and where is it located?
Double-stranded RNA; located on the inner surface of endocytic vesicles.
What does TLR4 recognize and where is it located?
Lipopolysaccharides (LPS); located on the plasma membrane of immune cells.
What does TLR5 recognize?
Flagellin, a protein in bacterial flagella.
What is triggered by detection of pathogens in mammals?
Phagocytosis and destruction of the pathogens.
What are the two main types of phagocytic cells?
Neutrophils and macrophages.
What do neutrophils do?
Circulate in blood and are attracted to infection sites by signals from infected tissues.
Where are macrophages commonly found?
In the spleen and other organs likely to encounter pathogens.
What do dendritic cells do in innate immunity?
Found in tissues that contact the external environment; help trigger adaptive immunity.
What do natural killer (NK) cells do?
Release chemicals that induce cell death in infected or cancerous cells.
What role does the lymphatic system play in innate immunity?
Supports circulation of immune cells and facilitates interaction with pathogens.
Where do dendritic cells migrate after encountering pathogens?
To lymph nodes to interact with other immune cells and activate adaptive immunity.
What are antimicrobial peptides and proteins?
Substances produced in response to pathogen recognition that disrupt or inhibit pathogens.
What are interferons?
Proteins secreted by virus-infected cells to help neighboring cells resist viral replication.
What does the complement system do?
A group of ~30 plasma proteins that enhance immune responses and cause pathogen lysis.
What activates the complement system?
Substances on the surface of microbes.
What is histamine and what does it do?
A signaling molecule released by mast cells; it dilates and increases permeability of blood vessels.
What are cytokines and what is their role in inflammation?
Proteins released by macrophages and neutrophils to increase blood flow and attract immune cells.
What causes pus formation?
Accumulation of white blood cells, dead pathogens, and tissue debris at the infection site.
What can happen during a systemic inflammatory response?
Fever, increased white blood cell production, and widespread immune activation.
How can pathogens evade innate immunity?
Some have capsules that prevent recognition or survive within host cells.
How does Streptococcus pneumoniae evade immune detection?
By using a capsule to avoid phagocytosis.
How does Mycobacterium tuberculosis survive in the body?
It resists breakdown in lysosomes and can reproduce within macrophages.
