52 Questions
Which of the following cells is a type of phagocyte?
Neutrophils
What is the main function of dendritic cells in the immune response?
To link innate and adaptive immune responses
Which cells are described as large granular lymphocytes?
NK cells
Which of the following statements about macrophages is true?
Macrophages respond nearly as rapidly as neutrophils and survive longer at the inflammation site.
Which of the following cell types are correctly matched with their roles in the immune response?
NK cells - Directly kill infected cells
Which component is part of the innate immune system and is always active?
Respiratory tract lining
What is a characteristic feature of the innate immune system recognition?
Recognizes structures that are essential for survival of microbes
What is an example of a cell-associated pattern recognition receptor (PRR) in the innate immune system?
Toll-like receptors
Which type of molecule can recognize microbial pathogens in the innate immune system?
Pentraxins
Which of the following functions is NOT associated with innate immunity?
Memory of past infections
Which of the following is an example of a physical barrier in the innate immune system?
Intact epithelial surfaces
What are pathogen associated molecular patterns (PAMP) recognized by?
Pattern recognition receptors
What is the role of mannose binding lectin (MBL) in the innate immune system?
Complement activation
Which of the following statements is true about intraepithelial lymphocytes?
They are found in both the epidermis of the skin and mucosa epithelia.
What role do cilia play in the respiratory tracts?
They move continuously to push out large particles.
Which of the following is true about lysozymes?
They dissolve bacterial cell walls.
What is the primary purpose of defensins in the immune system?
To produce pores in the membrane of bacteria and kill them.
Which of the following body sites typically has an acidic pH due to the action of lactobacillus?
Vagina
How do normal bacterial flora act as a biological barrier?
By producing inhibitory substances that suppress pathogenic growth.
What forms after lysosomal granules fuse with the phagosome?
Phagolysosome
What is the primary mechanism of the oxygen-dependent system in phagocytosis?
Production of reactive oxygen species
Which enzyme is produced in the oxygen-independent system?
Elastase
What shape is formed by the plasma membrane during phagocytosis?
Cup
Which of the following is NOT converted into reactive oxygen species in the oxygen-dependent system?
Water
Which organisms are adapted to grow in phagocytes?
Tubercle bacilli
What is the main function of phagocytes in response to invading microorganisms?
Capturing, ingesting, and digesting microorganisms
During the chemotaxis and migration phase, which cells are actively recruited to the site of infection?
Neutrophils and monocytes
What is the role of PRRs (pattern recognition receptors) on phagocytes?
To specifically recognize and attach to structures on microbes
What enhances the process of attachment and ingestion of microbes by phagocytes?
Opsonization by specific antibodies or complement C3b
What is formed after a phagocyte engulfs a microbe during the ingestion process?
Phagosome
Which mechanism involves highly reactive molecular oxygen species to destroy microbes?
Oxygen-dependent mechanism
What role do neutrophils play in the oxygen-independent mechanism?
Using proteolytic enzymes to destroy bacteria
What is the term for the process of coating microbes to target them for phagocytosis?
Opsonization
Which serum proteins are involved in the alternative pathway of complement activation?
Factor B & Factor D
Which cytokine is responsible for macrophage activation?
INF-γ
What is the function of interferons released from virus-infected cells?
Inhibit viral spread to neighbouring cells
TNF-α, IL-1, IL-6, and chemokines are primarily classified as which type of cytokines?
Pro-inflammatory cytokines
Which factor determines why N. gonorrhea only infects humans?
Species
Which cytokines are involved in the control of inflammation?
IL-10 and TGF-β
Which characteristic of adaptive immunity allows it to differentiate between own body cells and foreign substances?
Self and non-self recognition
What type of immunity is developed when the body is exposed to a foreign antigen and produces its own antibodies?
Active Immunity
Which form of immunity is typically transferred through breast milk?
Passive Immunity
Which characteristic of adaptive immunity is responsible for a stronger immune response upon re-exposure to the same antigen?
Memory
What type of immunity is provided by the transfer of readymade antibodies?
Passive Immunity
What is the role of complement proteins in the immune response?
They directly attack microbes or enhance their uptake by opsonization
How do macrophages recognize antigens during phagocytosis?
By binding to IgG and C3b on the antigen's surface
Which of the following is a role of acute-phase proteins?
They increase in response to inflammatory cytokines and aid in opsonization
Which factor does NOT influence the spread of an infection?
Availability of vaccines
What is a common reason why some individuals are more susceptible to leprosy?
Variations in genetic susceptibility among races
Which strain of bacteria is known for causing a highly contagious disease, as indicated in the content?
Mycobacterium tuberculosis
What is the role of C3b in phagocytosis?
It facilitates the binding of macrophages to the antigen
Which protein is associated with the inflammatory response and activation of complement during an infection?
C-reactive protein
Study Notes
Innate Immunity
- Innate immunity is the resistance an individual has by birth, providing immediate defense against infections
- Components of innate immunity include physical barriers, chemical barriers, and biological barriers
Function of Innate Immunity
- Prevents, controls, or eliminates infection of the host
- Stimulates adaptive immune response
Features of Innate Immune Recognition
- Recognizes structures characteristic of microbial pathogens (Pathogen Associated Molecular Patterns, PAMPs)
- Recognizes microbial products essential for survival
- Recognizes abnormal host cells
Recognition Molecules of Innate Immunity
- Cell-associated pattern recognition receptors (PRRs): Toll-like receptors (TLRs)
- Soluble recognition molecules: Pentraxins (C-reactive protein, CRP) and Collectins (mannose-binding lectin, MBL)
Components of the Innate Immune System
First Line of Natural Defense
- Physical barriers:
- Intact epithelial surfaces
- Lymphocytes (intraepithelial lymphocytes)
- Eye (tears and blinking reflex)
- Respiratory tracts (hair, mucous, and cilia)
- Chemical barriers:
- Acidic pH (skin, stomach, and vagina)
- Microbicidal action of secreted molecules (lysozymes and defensins)
- Digestive enzymes (saliva and small intestine)
- Biological barriers:
- Normal bacterial flora (supresses growth of pathogenic bacteria and fungi)
Second Line of Natural Defense
- Circulating effector cells:
- Phagocytes (neutrophils and macrophages)
- Natural killer (NK) cells
- Dendritic cells
- Phagocytosis of microbes:
- Chemotaxis and migration
- Recognition and attachment
- Ingestion
- Digestion or destruction
Ingestion
- Phagocytes recognize and attach to microbes through receptors
- Phagosome formation
- Lysosomal granule fusion
Digestion or Destruction of Ingested Microbes
- Oxygen-dependent system (reactive oxygen species)
- Oxygen-independent system (proteolytic enzymes)
Circulating Effector Proteins
- Complement system
- Acute-phase proteins (mannose-binding lectin, MBL, and C-reactive protein)
Inflammatory Response and Spread of Infection
- Factors that determine the spread of infection: species, race, microbe, and individual
- Inflammatory response: a complex sequence of events that limits the spread of infection
Interferon (INF)
- Released from virus-infected cells to inhibit viral spread to neighboring cells
Cytokines
- Part of innate immunity, involved in pro-inflammatory, anti-inflammatory, and immune responses
Factors that Determine Innate Immunity
- Species
- Races
- Individuals (health status, age, etc.)
Characters of Adaptive Immunity
- "Self" and "non-self" recognition
- Specificity
- Diversity
- Need prior exposure
- Memory (long-term immunity)
Types of Adaptive Immunity
- Passive immunity (readymade antibodies, temporary protection)
- Active immunity (body produces its own antibodies, long-lasting protection)
Learn about innate immunity, a natural resistance to infection that an individual possesses from birth, including its components and functions. Discover how it protects the body from microbes and pathogens.
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