Podcast
Questions and Answers
Which of the following is NOT a common type of normal bacterial microbiota?
Which of the following is NOT a common type of normal bacterial microbiota?
- Staphylococcus (correct)
- Lactobacillus
- Bifidobacterium
- Saccharomyces
Which of the following is a potential consequence of dysbiosis?
Which of the following is a potential consequence of dysbiosis?
- Increased risk of obesity (correct)
- Increased risk of antibiotic resistance
- Improved immune function
- Reduced risk of type 1 diabetes
What is the primary difference between a prebiotic and a probiotic?
What is the primary difference between a prebiotic and a probiotic?
- Prebiotics promote the growth of specific bacteria while probiotics kill harmful bacteria
- Probiotics promote the growth of specific bacteria while prebiotics kill harmful bacteria
- Prebiotics are living organisms while probiotics are food ingredients
- Probiotics are living organisms while prebiotics are food ingredients (correct)
How can bacteria in the gut affect carcinogenesis?
How can bacteria in the gut affect carcinogenesis?
What is the role of immunoglobulin A (IgA) in the gut?
What is the role of immunoglobulin A (IgA) in the gut?
What is the primary mechanism by which antibiotics can disrupt the gut microbiota?
What is the primary mechanism by which antibiotics can disrupt the gut microbiota?
Which of the following is NOT a potential consequence of a disrupted gut microbiome?
Which of the following is NOT a potential consequence of a disrupted gut microbiome?
Why do obese individuals tend to have lower bacterial diversity in their gut?
Why do obese individuals tend to have lower bacterial diversity in their gut?
What is the primary function of the O-antigen in bacterial cell walls?
What is the primary function of the O-antigen in bacterial cell walls?
Which of the following is NOT a characteristic of the periplasmic space in bacteria?
Which of the following is NOT a characteristic of the periplasmic space in bacteria?
What is the primary difference between Gram-positive and Gram-negative bacteria?
What is the primary difference between Gram-positive and Gram-negative bacteria?
What is the primary function of a capsule in bacteria?
What is the primary function of a capsule in bacteria?
How does bacterial chemotaxis contribute to bacterial occupancy?
How does bacterial chemotaxis contribute to bacterial occupancy?
What is the primary function of pili in bacteria?
What is the primary function of pili in bacteria?
Which type of transport mechanism does NOT require energy?
Which type of transport mechanism does NOT require energy?
What type of transport mechanism involves the chemical alteration of the transported molecule?
What type of transport mechanism involves the chemical alteration of the transported molecule?
Which of the following statements accurately describes the structure and function of peptidoglycan in bacteria?
Which of the following statements accurately describes the structure and function of peptidoglycan in bacteria?
What is the primary function of the outer membrane in Gram-negative bacteria?
What is the primary function of the outer membrane in Gram-negative bacteria?
Which of the following is NOT a characteristic of prokaryotes?
Which of the following is NOT a characteristic of prokaryotes?
Which of the following statements accurately describes the difference between Gram-positive and Gram-negative bacteria?
Which of the following statements accurately describes the difference between Gram-positive and Gram-negative bacteria?
Which of the following is a mechanism that bacteria use to survive environmental threats?
Which of the following is a mechanism that bacteria use to survive environmental threats?
Which of the following is NOT a survival mechanism used by bacteria?
Which of the following is NOT a survival mechanism used by bacteria?
Which of the following is NOT an example of an antibiotic that inhibits peptidoglycan synthesis?
Which of the following is NOT an example of an antibiotic that inhibits peptidoglycan synthesis?
Which of the following accurately describes the role of lipid A in the outer membrane of Gram-negative bacteria?
Which of the following accurately describes the role of lipid A in the outer membrane of Gram-negative bacteria?
Which of the following is TRUE regarding Gram-negative bacteria?
Which of the following is TRUE regarding Gram-negative bacteria?
Which of the following is NOT a characteristic of fungi?
Which of the following is NOT a characteristic of fungi?
Which of the following describes a dimorphic fungus?
Which of the following describes a dimorphic fungus?
Which of the following is a type of protozoa?
Which of the following is a type of protozoa?
What is the primary difference between helminths and ectoparasites?
What is the primary difference between helminths and ectoparasites?
What is the defining characteristic that separates viruses from both prokaryotic and eukaryotic organisms?
What is the defining characteristic that separates viruses from both prokaryotic and eukaryotic organisms?
Which of the following is NOT true of viruses?
Which of the following is NOT true of viruses?
Which of the following best describes the role of porin channels in Gram-negative bacteria?
Which of the following best describes the role of porin channels in Gram-negative bacteria?
What is the primary reason why LPS-containing pathogens might be able to evade the complement pathway?
What is the primary reason why LPS-containing pathogens might be able to evade the complement pathway?
Which of the following is NOT a consequence of recognizing an antigen by the innate immune system?
Which of the following is NOT a consequence of recognizing an antigen by the innate immune system?
Which of the following is a key characteristic of inflammation?
Which of the following is a key characteristic of inflammation?
Which of the following immune cells is directly involved in the process of phagocytosis?
Which of the following immune cells is directly involved in the process of phagocytosis?
Which of the following is NOT a direct consequence of complement activation?
Which of the following is NOT a direct consequence of complement activation?
What is the primary function of an eosinophil?
What is the primary function of an eosinophil?
Which of the following is NOT a characteristic of the acute phase response?
Which of the following is NOT a characteristic of the acute phase response?
What is the key function of the adaptive immune system?
What is the key function of the adaptive immune system?
Which type of cell is directly responsible for killing virus-infected or damaged cells?
Which type of cell is directly responsible for killing virus-infected or damaged cells?
What is the main role of antibodies produced by B cells?
What is the main role of antibodies produced by B cells?
What is the significance of the process of antigen presentation in the adaptive immune response?
What is the significance of the process of antigen presentation in the adaptive immune response?
What is the role of T cells in the adaptive immune response?
What is the role of T cells in the adaptive immune response?
Which of the following is NOT a mechanism by which antibodies can prevent microbial spread?
Which of the following is NOT a mechanism by which antibodies can prevent microbial spread?
What is the difference between B cells and plasma cells?
What is the difference between B cells and plasma cells?
What is the function of the CD4+ T cells in the adaptive immune response?
What is the function of the CD4+ T cells in the adaptive immune response?
Flashcards
Carcinogenic amines
Carcinogenic amines
Chemicals produced by bacteria that are linked to cancer, often from cooked meat.
Cyclamate conversion
Cyclamate conversion
The artificial sweetener cyclamate can be turned into the carcinogen cyclohexamine by bacteria.
Normal microbiota's role in immunity
Normal microbiota's role in immunity
Normal microbiota can stimulate the immune system, specifically producing antibodies like IgA.
Dysbiosis effects
Dysbiosis effects
Disruption of normal gut flora linked to anxiety, obesity, and autoimmune diseases.
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Prebiotic definition
Prebiotic definition
Food ingredients that promote the growth of beneficial gut bacteria, mostly fiber that humans can't digest.
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Probiotic definition
Probiotic definition
Live microorganisms that provide health benefits when consumed, often found in foods like yogurt.
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Antibiotics effect on gut microbiota
Antibiotics effect on gut microbiota
Antibiotics can alter the composition of gut microbiota, affecting both diversity and activity.
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Normal microbiota infection risk
Normal microbiota infection risk
When normal bacteria, like E. coli, end up in places they're not supposed to, they can cause infections.
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Eukaryotes vs Prokaryotes
Eukaryotes vs Prokaryotes
Eukaryotes have a nucleus; prokaryotes do not.
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Prokaryotic DNA
Prokaryotic DNA
Prokaryotic DNA is circular, while eukaryotic DNA is linear.
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Ribosome Types
Ribosome Types
Prokaryotes have 70S ribosomes; eukaryotes have 80S ribosomes.
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Reproduction Methods
Reproduction Methods
Prokaryotes reproduce by binary fission; eukaryotes by mitosis or meiosis.
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Gram Positive vs Gram Negative
Gram Positive vs Gram Negative
Gram-positive bacteria retain purple dye; gram-negative do not.
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Peptidoglycan Function
Peptidoglycan Function
Peptidoglycan protects against osmotic pressure and determines bacterial shape.
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Outer Membrane & LPS
Outer Membrane & LPS
LPS, with Lipid A, anchors to the outer membrane and acts as an endotoxin.
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Antibiotic Mechanism
Antibiotic Mechanism
Certain antibiotics inhibit peptidoglycan synthesis, affecting bacterial growth.
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Gram-positive bacteria
Gram-positive bacteria
Bacteria with thick peptidoglycan walls, retain iodine stain after alcohol wash.
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Gram-negative bacteria
Gram-negative bacteria
Bacteria with thin peptidoglycan walls and an outer LPS membrane, do not retain iodine stain.
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Fungi
Fungi
Eukaryotic organisms, usually multicellular, that are heterotrophs and play crucial roles in ecosystems.
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Eukaryotic
Eukaryotic
Cells with a nucleus and organelles such as mitochondria and Golgi apparatus.
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Chitin
Chitin
A rigid substance making up the cell walls of fungi.
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Spores
Spores
Reproductive units produced by fungi, can be involved in sexual or asexual reproduction.
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Protozoa
Protozoa
Single-celled eukaryotic organisms, often considered as part of the parasite group.
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Viruses
Viruses
Non-living entities that cannot reproduce without a host, not classified as prokaryotic or eukaryotic.
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LPS and MAC Interaction
LPS and MAC Interaction
LPS (lipopolysaccharide) can block the membrane attack complex (MAC), preventing cell lysis.
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Pathogens avoiding complement pathway
Pathogens avoiding complement pathway
Gram-negative bacteria can evade being killed due to the presence of LPS.
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Induced innate immunity overview
Induced innate immunity overview
Recognition of antigens leads to increased antimicrobial peptides and inflammation mediators.
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Complement activation
Complement activation
Activation of the complement system enhances phagocytosis, opsonization, and inflammation.
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Inflammation characteristics
Inflammation characteristics
Inflammation is marked by redness, heat, swelling, pain, and loss of function.
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Role of cytokines and chemokines
Role of cytokines and chemokines
These mediators are secreted during inflammation to attract immune cells to the infection site.
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Acute phase response
Acute phase response
A rapid increase in production of defensive proteins and pro-inflammatory mediators during infection.
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Erythema and edema
Erythema and edema
Erythema refers to increased blood flow, while edema refers to increased fluid in tissue during inflammation.
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Neutrophils
Neutrophils
A type of white blood cell crucial for the innate immune response.
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Adaptive Immune System
Adaptive Immune System
Immune system component that recognizes and remembers specific pathogens.
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Immunological Memory
Immunological Memory
Ability of the adaptive immune system to remember past infections.
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Antibodies
Antibodies
Proteins produced by B cells that bind to specific antigens.
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Cell-mediated Immunity
Cell-mediated Immunity
Immune response where T cells kill infected or damaged cells.
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B cells
B cells
Lymphocytes that produce antibodies after activation.
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Immunoglobulin
Immunoglobulin
Another name for antibodies, produced by plasma cells.
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Antigen Presentation
Antigen Presentation
Process where cells display antigens to activate T cells.
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Core polysaccharide
Core polysaccharide
A component of lipopolysaccharides composed of short sugar chains.
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O-antigen
O-antigen
Hydrophilic carbohydrate chains that help bacteria evade hydrophobic compounds.
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Periplasmic space
Periplasmic space
The compartment between two membranes containing nutrients and enzymes.
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Acid-fast bacteria
Acid-fast bacteria
Bacteria with waxy cell walls requiring special staining techniques.
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Capsule function
Capsule function
A protective slimy coating around bacteria to prevent phagocytosis.
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Flagella
Flagella
Long, helical filaments that provide motility to bacteria.
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Pili (fimbriae)
Pili (fimbriae)
Hair-like structures for attachment to surfaces.
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Active transport
Active transport
Movement of molecules into a region of higher concentration using energy.
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Human Microbiome
- Estimated to have over 100 trillion bacteria, outnumbering human cells.
- Bacterial genes greatly outnumber human genome, more than 100x.
- The microbiome may weigh 3 to 4 pounds, as much as the human brain.
- The microbiome aids in digestion and immune system regulation.
- It assists in producing B12, thiamine, riboflavin and vitamin K (essential for blood coagulation).
- Crucial role in the gut-brain axis.
The Virome
- There are approximately 10 quintillion virus particles on the planet.
- Viruses outnumber bacteria 10 to 1 in most ecosystems
Class Objectives
- Define vocabulary words and use them appropriately.
- Identify normal microbiota and areas of colonization.
- Define opportunistic and strict pathogens (DITKI).
- List examples of normal microbiota ("flora").
- Understand dysbiosis and its consequences.
- Compare and contrast probiotics and prebiotics.
- Define tissue tropism and identify requirements for it.
- Learn the 6 steps required for the establishment of infectious diseases.
- Apply material to clinical settings.
Microbiota
- Core microbiome- species present at a specific site in 95% or more of individuals.
- Secondary microbiome- species present in smaller numbers at specific sites, varying between individuals.
- Normal flora depends on pathogenicity, virulence & host response.
- Often a mutualistic relationship.
Normal Microbiota
- Common locations include: skin (especially moist areas), respiratory tract (nose and oropharynx), digestive tract (mouth and large intestine), urinary tract (anterior urethra), and genital system (vagina).
- Less common: rest of respiratory and digestive tract, urinary bladder, and uterus.
- Diagnostically significant locations include: blood, cerebrospinal fluid (CSF), synovial fluid, and deep tissues.
Role of Normal Flora
- Keeping out invaders, like inhibiting new microbial arrivals via bacteriocins.
- Role in human nutrition and metabolism, like synthesis of vitamins K and B.
- Conversion of ingested compounds, where some bacteria modify carcinogenic compounds into less harmful substances.
- Example with cyclamate, where it's transformed into a carcinogen.
Role of Normal Microbiota (cont.)
- Immune stimulation. Normal microbiota can stimulate antibodies (like IgA).
- Common source of infection, where normal microbiota can cause disease in immunocompromised individuals, or if moved to a new body niche.
Frequent Types of Normal Bacterial Microbiota
- Effect of antibiotics on gut microbiota.
- Fecal samples were collected from 4 antibiotic-treated patients (A, B, C, D) to study changes.
- Changes in microbiota were observed both during and after treatment.
What Happens When the Normal Microflora is Disrupted?
- Dysbiosis is linked with anxiety, depression, schizophrenia (90% of serotonin produced in the gut).
- Dysbiosis has a close link with other conditions, such as obesity, type I diabetes, celiac disease, and various other chronic diseases.
Bristol Stool Chart
- A chart describing 7 different stool types.
Probiotic vs. Prebiotic
- Prebiotic- food ingredient that supports the growth of microbes. Comes from types of carbohydrates (mostly fiber) that humans cannot digest.
- Probiotic – live organism, when ingested, provides benefits. Typically gram-positive bacteria (e.g., Bifidobacterium, Lactobacillus) or yeasts (e.g., Saccharomyces). Found in supplements (yogurt, kefir, kombucha)
Tissue Tropism of Infectious Agents
- Site of entry (e.g., Gonococcus: genital tract; HIV: any site).
- Host receptors (e.g., ACE2 with SARS-CoV-2).
- Temperature differentials (e.g., conditions at the foot are different from those in the interior of the body).
Bacterial Colonization
- Resisting host defenses.
- Competing with other microbes.
- Taking advantage of host features like fibronectin on epithelial cells in poor health or in hospitals, the presence of fibronectin decreases, and gram-negative infections increase, like gram-negative pneumonia.
- Antimicrobial properties of the host are also important for colonization.
Bacterial Colonization (cont.)
- Microbial strategies to overcome those properties include adherence to epithelial cells to avoid getting engulfed, killing phagocytic cells, acquiring nutrients from host cells, modifying surface molecules to avoid being targeted, and using other techniques to survive.
Establishment of Infectious Diseases
- Encounter (agent meets host).
- Entry (agent enters host).
- Spread (agent travels to different body sites from entry site).
- Multiplication (agent increases in number).
- Damage (agent, host response, or both harm the host).
- Outcome, (where either pathogen or host survives).
Encounter
- Fetus is usually sterile, but encounters some pathogens.
- First encounter occurs at birth when exposed to mother's antibodies and colostrum.
- Exogenous vs endogenous: Exogenous means a pathogen comes in from outside the body, and endogenous is a pathogen originating from inside (e.g. normal flora).
Entry
- Microorganisms enter the body through cavities (like nose, mouth, respiratory).
- Ingestion via food or water can cause entry (e.g., cholera, food poisoning).
- Microbial penetration happens when it passes through epithelial barriers, such as after insect bites, cuts & wounds & spread elsewhere
Spread
- Lateral propagation—spreading to neighboring areas
- Dissemination—traveling to distant sites
Multiplication
- Incubation period - time needed for infectious agents to overcome the host defenses.
- Environmental factors affect multiplication
- Constitutive defenses – need to evade host defenses– examples: complement and phagocytosis
- Induced defenses: examples, humoral and cellular immunity
Damage
- Type and intensity depends on tissue or organ affected.
- Not always direct damage, can be due to host immune response.
- Direct tissue damage by toxins, cell death, and harmful effects of endotoxins (i.e., LPS).
Outcome
- Depends on steps from encounter to damage.
- Was there infection (encounter)?
- Was the entry successful?
- Did the pathogen spread locally or to distant tissues?
- Did the pathogen multiply successfully?
- Did damage result?
- Subverted normal host immune response?
Test Your Knowledge #2
- What are the six things needed to establish viral infection?
- Encounter
- Entry
- Spread
- Multiplication
- Damage
- Outcome
Key Virological Principles
- Virus-host interactions that can be permissive or non-permissive for certain cells
- Virus host interactions dictate severity & duration of infection or disease
- Cells have characteristics for viral infections- which can be cellular infections, aborted infections, cytolytic infections, persistent & chronic infection & oncogenic infections
Basic Characteristics of Pathogens
- Antibiotic-resistant infections and deaths
- Number of bacteria and fungi that pose a threat to the US
Also a Scientist
- Information about researchers and their contributions; including, contributions to vaccines, microbiology, research.
Basic Characteristics of Pathogens (cont.)
- Discussion about the threat from infectious agents in general (bacteria & fungi).
Host Pathogen Interactions Pt. I
- Introduction to the topic
Immunity (cont.)
- Innate and adaptive immunities
- Physical, chemical, and cellular defenses
- Active and passive immunities (natural and artificial/vaccination/maternal
Innate vs. Adaptive Immunity
- Receptors (germline-encoded vs generated by somatic genetic recombination).
- Receptor distribution (variety of cell types vs clonally expressed on lymphocytes).
- Memory- (none or limited vs vast).
Cells of innate & adaptive immune system
- Innate & adaptive immune systems come from a multipotent hematopoietic stem cell
Innate Immune System
- Early, generalized, first-line defense.
- Recognize microbes via pattern recognition receptors.
- Stimulates adaptive immune responses after recognition of microbes
Innate Immune System (cont.)
- Components based on cellular (Phagocytic cells, Pro-inflammatory cells, Natural Killer cells, Dendritic cells) and humoral (Cytokines, Complement) roles
Components of the Innate Immune System - Cellular
- Skin
- Mucous membrane surfaces
- Phagocytic: cells (neutrophils, macrophages)-ingest and kill bacteria
- Pro-inflammatory: cells (macrophages, mast cells, eosinophils, basophils)-induce host defenses.
- Antigen Presenting cells (APCs)-recognize, process & present antigen to lymphocytes to initiates adaptive immunity
- Natural Killer cells- kill infected or damaged cells like cancer
- Neutrophil extracellular traps (NETs)- DNA (histones, granule proteins released by neutrophils, which "catch" microbes.
Components of the Innate Immune System - Humoral
- Bile, gastric acid, mucus, tears, and normal microbiota
Complement- "complements antibodies"
- Overall role- Makes invading microbes more susceptible to phagocytosis.
- Promotes the inflammatory response.
- Produces substances that attract white blood cells.
- Lyses some microorganisms.
- Classical, Alternative, & Lectin pathways
Test Your Knowledge
- LPS can block the MAC, so gram-negative bacteria would most likely avoid being killed.
Consequences of Recognizing Antigen: Induced Innate Immunity
- Increased antimicrobial peptides are produced
- Inflammation & inflammatory mediators; example, cytokines, chemokines, etc.
- Activation of complement
Inflammation
- Characterized by redness, heat, swelling, and pain.
- Leads to loss of function
Adaptive Immune Response
- Initial step when innate immunity fails
- Antibodies recognize & bind to microbial epitopes; preventing spread, attachment, promoting phagocytosis.
- Cell-mediated immunity – leukocytes destroy invading cells
Lymphocytes
- CD8 cytotoxic T cells - kill virus-infected & damaged cells.
- CD4 helper T cells- assist cytotoxic T & B cells.
- B cells (plasma cells) – produce antibodies.
- Regulatory T cells- modulate the immune response.
Lymphocyte Development, Activation, & Antigen Presentation
- T & B cells undergo development to distinguish self from non-self.
- T cells that wrongly identify self are not selected
- Cells become active when presented with an antigen
- Activated helper T cells proliferate and secrete cytokines to activate other cells (CD8 T cells & B cells).
- Activated cytotoxic T cells kill cells with the antigen.
- Activated B cells proliferate & synthesize Immunoglobulins.
Immunoglobulins
- Immunoglobulin, aka antibodies, are glycoprotein molecules.
- IgG, IgE, IgM, IgA, IgD
Initiation of Adaptive Immune Responses by Innate Immunity (AKA Antigen Presentation)
- Microbial antigen appears
- Dendritic cell recognizes microbe via pattern recognition receptors
- Dendritic cell takes up microbial antigen, migrates to lymph node, matures
- Dendritic cell processes the antigen, loads it onto MHC class II molecules
- Dendritic cell presents antigen to CD4+ helper T cells
- Activated CD4 T cells activate B cells that differentiate into plasma cells
- Plasma cells produce antibodies, eliminating the antigen
Major Histocompatibility Complex (MHC)
- Glycoproteins found on different cells, upregulated during innate immunity.
- Used in antigen recognition to activate T cells.
- MHC class I
- presents endogenous antigens
- Found on all nucleated cells
- presents antigen to Cytotoxic (CD8) T cells
- MHC class II
- presents exogenous antigens
- Found on APCs (dendritic cells, macrophages, B cells)
- presents antigen to Helper (CD4) T cells
Immunological Memory
- Once an organism stimulates adaptive response, there's memory to prevent subsequent exposures from having same effects.
- Enhanced actions from antibodies and effector T cells
Test Your Knowledge #3
- What are the differences between MHC class I and class II?
- MHC Class I presents endogenous antigens from the cytoplasm, found on all nucleated cells, and presents antigen to cytotoxic (CD8) T cells.
- MHC Class II presents exogenous antigens, found on antigen-presenting cells (APCs), and presents antigen to helper (CD4) T cells.
Also a Scientist
- Information about scientists.
- Includes their work & contributions
Additional Notes
- Various additional notes on different topics.
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Description
Test your knowledge on the role of bacterial microbiota in gut health. This quiz covers important concepts such as dysbiosis, prebiotics vs. probiotics, and the effects of gut bacteria on immunity and carcinogenesis. Explore fundamental differences between various types of bacteria and their functions.