1What does innate mean in innate immunity?
Present from birth.
2What are the two major branches of the immune system?
Innate immunity and adaptive immunity.
3What are the main characteristics of innate immunity?
It is rapid, always available, and relatively nonspecific.
4What does it mean that innate immunity is nonspecific?
It recognizes common features shared by groups of pathogens rather than one specific pathogen.
5What are the major components of innate immunity?
Normal microbiota, physical barriers, chemical defenses, and cellular defenses.
6How do normal microbiota protect the host?
They compete with pathogens and make it harder for them to colonize the body.
7How can normal microbiota compete with pathogens for resources?
They consume nutrients that pathogens would otherwise use.
8How can normal microbiota compete with pathogens for attachment sites?
They occupy surfaces where pathogens might otherwise attach.
9How can normal microbiota chemically inhibit pathogens?
They can produce acids or antimicrobial substances that inhibit or kill other microbes.
10What can happen when antibiotics disrupt normal intestinal microbiota?
Pathogens such as *Clostridioides difficile* may overgrow.
11How can *C. difficile* cause disease after antibiotic treatment?
It can colonize the intestine and produce toxins that damage the intestinal lining.
12What is antibiotic-associated colitis?
Inflammation of the colon that can occur when antibiotics disrupt normal microbiota and allow *C. difficile* to overgrow.
13What is the role of skin in innate immunity?
It acts as a physical barrier that prevents microbes from entering the body.
14How does mucus help defend the body?
It traps microbes and helps remove them from body surfaces.
15What is lysozyme?
An antimicrobial enzyme that damages bacterial cell walls.
16What are antimicrobial peptides?
Small proteins that can damage or inhibit microorganisms.
17What is phagocytosis?
The process by which a cell engulfs and digests particles or microorganisms.
18What are phagocytes?
Cells that engulf and destroy microbes by phagocytosis.
19What are examples of phagocytic cells?
Neutrophils and macrophages.
20What is inflammation?
A nonspecific response to tissue damage or infection.
21What are the four classic signs of inflammation?
Redness, heat, swelling, and pain.
22What causes blood vessels to dilate during inflammation?
Inflammatory mediators such as histamine.
23What is vasodilation?
Widening of blood vessels, which increases blood flow to an area.
24Why do blood vessels become more permeable during inflammation?
To allow fluid and immune components to move from the blood into affected tissues.
25What is chemotaxis?
Directed movement of cells toward a chemical signal.
26Why is chemotaxis useful during infection?
It attracts immune cells toward the site where pathogens are present.
27What are mast cells?
Immune cells that release inflammatory mediators such as histamine.
28What is the complement system?
A group of blood proteins that activate in a cascade to help eliminate pathogens.
29What is a complement cascade?
A sequence in which activation of one protein leads to activation of additional proteins.
30What are major outcomes of complement activation?
Inflammation, chemotaxis, opsonization, and direct microbial killing.
31What is opsonization?
Coating a pathogen to make it easier for phagocytes to recognize and engulf.
32What is the membrane attack complex (MAC)?
A group of complement proteins that forms a pore in a target membrane.
33How does the membrane attack complex kill susceptible microbes?
It creates holes in their membranes, disrupting membrane function.
34What is the key convergence point of the complement pathways?
Activation of complement protein C3.
35What are the three complement activation pathways?
Classical, alternative, and lectin pathways.
36What activates the classical complement pathway?
Antibodies bound to antigens on a pathogen.
37Why does the classical pathway connect innate and adaptive immunity?
It uses antibodies produced by the adaptive immune system to activate complement.
38What activates the alternative complement pathway?
Complement activation on microbial surfaces without requiring antibodies.
39What activates the lectin complement pathway?
Binding of mannose-binding lectin to certain sugars on microbial surfaces.
40What does C3b do during complement activation?
It helps opsonize pathogens and promotes further complement activation.
41What do C3a and C5a help stimulate?
Inflammation and recruitment of immune cells.
42What is the purpose of the membrane attack complex?
To damage susceptible pathogen membranes by forming pores.