Podcast
Questions and Answers
What is the primary role of basophils in the immune system?
What is the primary role of basophils in the immune system?
- Facilitation of allergic reactions and inflammation (correct)
- Production of antibodies
- Detection of viral infections
- Phagocytosis of pathogens
Which of the following cells primarily are responsible for host defense and housekeeping in tissues?
Which of the following cells primarily are responsible for host defense and housekeeping in tissues?
- Natural Killer Cells
- Dendritic Cells
- Monocytes (correct)
- Basophils
What is one of the functions of cytokines in the immune system?
What is one of the functions of cytokines in the immune system?
- Directly kill infected cells
- Facilitate communication between cells (correct)
- Generate antibodies
- Process viral RNA
What type of immunity are B-cells primarily associated with?
What type of immunity are B-cells primarily associated with?
What does the term 'innate' refer to in the context of immune responses?
What does the term 'innate' refer to in the context of immune responses?
Which cytokine is most associated with regulating immune responses and controlling viral infections?
Which cytokine is most associated with regulating immune responses and controlling viral infections?
What complication can arise from the overproduction of cytokines in response to certain pathogens?
What complication can arise from the overproduction of cytokines in response to certain pathogens?
What is the primary role of barriers in the innate immune system?
What is the primary role of barriers in the innate immune system?
What is the primary function of Dendritic Cells in the immune system?
What is the primary function of Dendritic Cells in the immune system?
Which of the following is NOT an issue with the skin as a barrier?
Which of the following is NOT an issue with the skin as a barrier?
How does the mucosal membrane function as both a barrier and a door?
How does the mucosal membrane function as both a barrier and a door?
Which immune cells are part of the innate immune response with the ability to kill infected or abnormal cells?
Which immune cells are part of the innate immune response with the ability to kill infected or abnormal cells?
What is the primary purpose of the secretion of mucous in mucosal membranes?
What is the primary purpose of the secretion of mucous in mucosal membranes?
What type of agents do sensors in the innate immune response detect?
What type of agents do sensors in the innate immune response detect?
Which of the following correctly describes the outermost layer of skin?
Which of the following correctly describes the outermost layer of skin?
What type of substances do mucosal membranes secrete to help kill pathogens?
What type of substances do mucosal membranes secrete to help kill pathogens?
What is the primary function of lysozyme?
What is the primary function of lysozyme?
Which class of white blood cells is known for having a short lifespan, typically measured in hours?
Which class of white blood cells is known for having a short lifespan, typically measured in hours?
How do normal flora help prevent infections?
How do normal flora help prevent infections?
What role do defensins play in the immune response?
What role do defensins play in the immune response?
Which type of cell is primarily involved in clotting?
Which type of cell is primarily involved in clotting?
What characteristic is unique to eosinophils?
What characteristic is unique to eosinophils?
Which of the following is NOT a function attributed to normal flora?
Which of the following is NOT a function attributed to normal flora?
What type of white blood cell has a nucleus that fills most of the cell?
What type of white blood cell has a nucleus that fills most of the cell?
What is the primary role of cytokines in the inflammatory response?
What is the primary role of cytokines in the inflammatory response?
Which of the following terms refers to inflammation?
Which of the following terms refers to inflammation?
How do blood vessels respond during inflammation?
How do blood vessels respond during inflammation?
Which of the following is a symptom commonly associated with the body's inflammatory response?
Which of the following is a symptom commonly associated with the body's inflammatory response?
What can excessive inflammation lead to in the case of a blood infection?
What can excessive inflammation lead to in the case of a blood infection?
Chronic inflammation can be caused by all the following EXCEPT?
Chronic inflammation can be caused by all the following EXCEPT?
What is a cytokine storm?
What is a cytokine storm?
What effect do proinflammatory cytokines have on the body’s thermostat?
What effect do proinflammatory cytokines have on the body’s thermostat?
What is the primary function of the complement system?
What is the primary function of the complement system?
Which of the following correctly describes the activation of the complement system?
Which of the following correctly describes the activation of the complement system?
What role do macrophages play in the immune system?
What role do macrophages play in the immune system?
Which statement best describes the relationship between phagocytosis and macrophages?
Which statement best describes the relationship between phagocytosis and macrophages?
What is a possible outcome of the activation of C3b in the complement cascade?
What is a possible outcome of the activation of C3b in the complement cascade?
What is the primary function of inactive viral proteins (iAVPs) when a cell is primed?
What is the primary function of inactive viral proteins (iAVPs) when a cell is primed?
Which of the following triggers the complement system?
Which of the following triggers the complement system?
Which receptors are responsible for detecting various microbial patterns?
Which receptors are responsible for detecting various microbial patterns?
Which of the following is a common type of Pattern Recognition Receptor found in the membranes of sentinel cells?
Which of the following is a common type of Pattern Recognition Receptor found in the membranes of sentinel cells?
What is the significance of granulomas in the immune response?
What is the significance of granulomas in the immune response?
How does the immune system control the complement cascade?
How does the immune system control the complement cascade?
What initiates the activation of iAVPs in a cell?
What initiates the activation of iAVPs in a cell?
Which of the following is not a type of damage-associated molecular pattern (DAMP)?
Which of the following is not a type of damage-associated molecular pattern (DAMP)?
Where are cytoplasmic pattern recognition receptors (PRRs) primarily classified?
Where are cytoplasmic pattern recognition receptors (PRRs) primarily classified?
Which type of TLRs would be responsible for monitoring the extracellular environment?
Which type of TLRs would be responsible for monitoring the extracellular environment?
What is one outcome of when a virus is detected in a primed cell?
What is one outcome of when a virus is detected in a primed cell?
Flashcards
Innate Immunity
Innate Immunity
The body's inborn defenses against common threats, existing from birth.
Barriers (Innate Immunity)
Barriers (Innate Immunity)
The body's first line of defense against invading pathogens, preventing entry.
Skin Barrier
Skin Barrier
Multiple layers of epithelial cells, creating a hard, waterproof barrier.
Mucosal Membranes
Mucosal Membranes
Membranes lining body openings, allowing transport but needing defenses.
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Mucosal Shedding and Washing
Mucosal Shedding and Washing
Mucosal membranes use shedding and mucus movement to remove pathogens.
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Antimicrobial Substances (Mucosa)
Antimicrobial Substances (Mucosa)
Enzymes and peptides in mucosal membranes that kill pathogens.
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First Line Defenses
First Line Defenses
The initial physical and chemical barriers against pathogen entry, like skin and mucous membranes.
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Adaptive Immunity
Adaptive Immunity
The acquired immune responses that develop after exposure to a pathogen, not present from birth
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Lysozyme function
Lysozyme function
Lysozyme degrades peptidoglycan, a component of bacterial cell walls.
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Peroxidases role
Peroxidases role
Peroxidases produce reactive oxygen species to kill microbes and break down hydrogen peroxide.
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Iron-binding proteins
Iron-binding proteins
Proteins like lactoferrin and transferrin bind iron, making it unavailable to microbes for growth.
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Defensins mechanism
Defensins mechanism
Defensins (specialized defense peptides) form pores in microbial membranes, disrupting their structure and function.
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Neutrophils function
Neutrophils function
Neutrophils are white blood cells that phagocytose (engulf) microbes and kill them, or degranulate; a key part of pus.
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Eosinophils role
Eosinophils role
Eosinophils are white blood cells that stain with eosin and use granules to defend against pathogens.
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Normal flora role
Normal flora role
Normal flora competes with pathogens for resources and produces toxic compounds, preventing pathogen growth.
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White blood cells types
White blood cells types
White blood cells are categorized as granulocytes (with granules), mononuclear phagocytes (smooth nucleus), and lymphocytes (smaller cells, nucleus filling the cell).
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Histaminase
Histaminase
An enzyme found in granules of certain cells, particularly mast cells and basophils, that breaks down histamine.
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Basophils
Basophils
White blood cells that contain granules filled with histamine and other inflammatory mediators, playing a role in allergic reactions and inflammation.
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Macrophages
Macrophages
Professional phagocytes that reside in tissues, engulfing and digesting pathogens and cellular debris, crucial for host defense and tissue maintenance.
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Dendritic Cells
Dendritic Cells
Sentinel cells that patrol tissues, constantly gathering antigens and presenting them to other immune cells, initiating adaptive immune responses.
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B-cells
B-cells
Lymphocytes responsible for humoral immunity, producing antibodies that target specific pathogens.
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T-cells
T-cells
Lymphocytes responsible for cellular immunity, directly attacking infected cells or activating other immune cells.
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Natural Killer Cells
Natural Killer Cells
Lymphocytes that kill infected cells or tumor cells without prior sensitization, representing an innate defense mechanism.
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Cytokines
Cytokines
Small signaling molecules produced by cells that communicate with other cells, coordinating immune responses and influencing various cellular processes.
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iAVPs
iAVPs
Inactive viral proteins synthesized by neighboring cells to prime defenses against viruses.
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How do iAVPs get activated?
How do iAVPs get activated?
iAVPs are activated only when a virus is detected inside a primed cell.
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What does iAVP activation do?
What does iAVP activation do?
Activated iAVPs trigger a cascade of responses in the infected cell: degradation of mRNA, halting protein synthesis, and ultimately programmed cell death (apoptosis).
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What are PRRs?
What are PRRs?
Pattern Recognition Receptors (PRRs) are specialized proteins that recognize specific patterns associated with microbes, pathogens, or cellular damage.
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What are MAMPs?
What are MAMPs?
Microbe-associated molecular patterns (MAMPs) are molecules found on the surface of various microbes, indicating their presence.
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What are PAMPs?
What are PAMPs?
Pathogen-associated molecular patterns (PAMPs) are molecules specific to pathogens, indicating a harmful infection.
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What are DAMPs?
What are DAMPs?
Damage-associated molecular patterns (DAMPs) are signals released from damaged cells, indicating tissue injury or stress.
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Where are PRRs located?
Where are PRRs located?
PRRs can be found in different locations: on the cell surface, in phagosomes and endosomes, and even within the cytoplasm.
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PRRs & Cytoplasmic Markers
PRRs & Cytoplasmic Markers
Pattern Recognition Receptors (PRRs) can identify specific molecules in the cytoplasm of cells, helping the immune system detect signs of infection or damage.
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Complement Cascade
Complement Cascade
A series of proteins (C1-C9) that work together in a chain reaction, called a cascade, to help fight infection. Precursor proteins are activated in a specific order, amplifying the immune response.
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What does the Complement Cascade do?
What does the Complement Cascade do?
The Complement system has several key functions in fighting infection: it can "opsonize" (coat) pathogens, triggering phagocytosis by immune cells; it can trigger inflammation; and it can directly damage invading organisms.
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C3 protein
C3 protein
A key protein in the complement cascade. It can be cleaved into two parts: C3a which triggers inflammation, and C3b which opsonizes pathogens and activates further cascade steps.
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Phagocytosis
Phagocytosis
A process by which immune cells engulf and destroy pathogens or cellular debris. This is a key part of the innate immune response.
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Granulomas
Granulomas
Special structures formed by macrophages and lymphocytes to wall off infection. They can contain pathogens, but the organism may still be alive.
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Tuberculosis (TB) and Granulomas
Tuberculosis (TB) and Granulomas
TB can form granulomas in the lungs, which can interfere with lung function. This is because the bacteria may still survive inside the granuloma, even though it's walled off.
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Inflammation
Inflammation
A complex biological response to tissue damage, characterized by redness, swelling, heat, and pain, usually caused by infection or injury.
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What are Cytokines?
What are Cytokines?
Small signaling molecules that coordinate immune responses by communicating between cells, attracting immune cells and promoting inflammation.
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What is Pus?
What is Pus?
A thick, yellowish fluid formed during inflammation containing dead white blood cells, bacteria, and tissue debris.
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What are the effects of inflammatory mediators?
What are the effects of inflammatory mediators?
Inflammatory mediators like TNF, histamine, and others trigger blood vessel dilation (increasing blood flow), increased permeability (allowing fluid and cells to leave the bloodstream), and attract immune cells.
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What is 'itis'?
What is 'itis'?
A suffix in medical terms indicating inflammation of a specific body part.
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What causes excessive inflammation?
What causes excessive inflammation?
Conditions like sepsis (blood infection), toxin-induced stimulation, or cytokine storms can lead to systemic inflammation, affecting the entire body.
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How does fever happen?
How does fever happen?
Proinflammatory cytokines signal the brain to raise the body's temperature (fever) as a defense mechanism against infection.
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Innate Immunity
- Innate immunity is present from birth
- It defends the body against common threats
- Barriers prevent entry of infectious agents
- Sensors detect signs of external agents
- Effectors quickly respond to general threats
Barriers: Skin
- Multiple layers of epithelial cells
- Outermost layers are dead and keratinized
- Hard for pathogens to penetrate
- Hostile environment (arid, high salt)
- External layer sheds, removing pathogens
- Effective barrier in most cases
- Issues with degradation from moisture
- Mechanical abrasion or penetration
- Penetration by specialized biochemistry (e.g., parasites)
- Limited in nutrient/waste exchange
Barriers: Mucosal Membranes
- Areas needing transport and moisture
- Barriers and doors simultaneously
- Contained spaces, making shedding difficult
- Mucosal Membranes: Shed and Wash
- Secrete sticky mucus
- Move mucus to disposal areas
- Shed cells along the way for additional defense
Mucosal Membrane – Antimicrobial Substances
- Wide range of killing enzymes and peptides (e.g., lysozyme, peroxidases)
- Break down hydrogen peroxide
- Lactoferrin and transferrin bind iron (required for many microbes to grow)
- Specialized defense peptides (HDPs)
- Defensins form pores in microbial membranes
Recruiting Microbial Allies – Normal Flora
- Competitive exclusion of pathogens
- Consume available nutrients
- Production of toxic compounds (e.g., fatty acids from Cutibacterium species)
- Beneficial bacteria (e.g., E. Coli and lactobacilli) produce substances to protect from pathogens
Defenses in Blood and Lymph
- Specialized cells derived from hematopoietic stem cells
- Three general classes:
- Red blood cells (erythrocytes): oxygen transport
- Platelets (thrombocytes): clotting
- White blood cells (leukocytes): body defenses
White Blood Cells
- Originally categorized by microscopic appearance
- Granulocytes (e.g., neutrophils, eosinophils, basophils)
- Granules in the cytoplasm seen via specific stains
- Mononuclear phagocytes (e.g., monocytes, macrophages, dendritic cells)
- Smooth nucleus with clear cytoplasm
- Lymphocytes (covered in a separate section)
Granulocytes (Neutrophils, Eosinophils, Basophils)
- Neutrophils: short lifespan, major component of pus, kill by fusing with granules, attack by degranulating, increase with infection
- Eosinophils: combat parasites and allergies
- Basophils: contain histamine, roles in allergic reactions and inflammation
Mononuclear Phagocytes (Monocytes, Macrophages, Dendritic Cells)
- Monocytes: circulate in blood, become macrophages in tissues, professional phagocytes, specialized by tissue, host defense, housekeeping
- Macrophages: engulf and destroy pathogens
- Dendritic cells: sentinel cells that collect material from wide area, present to other immune cells
Lymphocytes
- Major part of adaptive immunity
- Two primary subtypes (B-cells and T-cells) with similar appearance
- B-cells: humoral immunity (antibodies)
- T-cells: cellular immunity (attack infected cells)
- Natural Killer cells: innate ability to kill certain types of cells
Cell Communication
- Cytokines, chemokines, colony-stimulating factors (CSFs), interferons (IFNs), interleukins (ILs), tumor necrosis factor (TNF)
- Cytokine storms: overproduction of cytokines in response to certain pathogens
What Triggers a Response?
- Pattern Recognition Receptors (PRRs) recognize indicators of attack (Microbes, Pathogens, Damage):
- Pathogen-associated molecular patterns (PAMPs)
- Damage-associated molecular patterns (DAMPs)
- Microbe-associated molecular patterns (MAMPs)
PRRs in Cytoplasm
- Book classifies PRRs by "RIG-like" (RLRs) and "NOD-like" (NLRs)
- Function to detect and identify markers of microbial and cellular damage
Soluble Enzymes in a Cascade
- Required proteins are often present in inactive precursors
- Multiple activation steps amplifying the response rapidly
Complement
- Consisting of multiple proteins working together (C1-C9)
- Initiated by multiple triggers including invading microorganisms, lectins, and antibodies
- Potential effects include opsonization, inflammation, and membrane punching
Phagocytosis
- Phagocytes "eat" by grabbing suspicious material
- Surround the material with pseudopods
- Direct lysosomes to fuse, digesting contents
- Phagocytosis is essential for debris removal
Macrophages
- Professional phagocytes
- Pick up everything: dead cells, trash, invaders
- Live for weeks/months
- Alert and recruit other immune cells
- Granulomas to wall off disease-causing agents
Inflammatory Response
- PRRs (or complement) detect invaders
- Cytokines mark the area, attract help (neutrophils)
- Cause blood vessels to increase in size and become leaky to allow movement of leukocytes into tissue
- Stimulates adhesion molecules on epithelial cells
- Usually controlled but some areas are more sensitive to inflammation
Inflammation (-itis)
- "-itis" suffix means inflammation
- Examples: gastritis, meningitis, otitis media, gingivitis
- Common symptoms like swelling and redness are caused by inflammatory mediators
Excessive Inflammation
- Blood infections (sepsis) can lead to systemic inflammation ("shock")
- Toxins induced stimulation
- Cytokine storm
- Chronic inflammation is part of several conditions (e.g., Rheumatoid Arthritis) or chronic stress, obesity, excessive red meat
Fever
- Proinflammatory cytokines reset the body's thermostat to a higher temperature
- Inhibit microbial growth, increase metabolism of immune cells, and increase efficiency of antimicrobial enzymes
Homework: Macrophages and Tattoos
- Investigate the link between macrophages and tattoos,
- Assess the net effect on the structure and duration of the tattoo, and
- Provide a citation.
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