38 Questions
What is the main challenge faced by the genitourinary tract in terms of immune protection?
Protecting the mother and preventing infection of the fetus during pregnancy
What is the term used to describe the normal microorganisms residing in the gastrointestinal tract?
Microbiome
What is the role of mucus in the mucosal surfaces of the genitourinary tract?
To form a protective layer over the epithelia
Which portal serves as the main entrance for pathogens to gain access to the body?
Respiratory tract
What type of cells provide physical defense in the genitourinary tract?
Epithelial cells
Which of the following is NOT an example of antimicrobial peptides produced by epithelial cells in the genitourinary tract?
Sphingomyelinase
Which protein, produced almost exclusively by urinary tract epithelial cells, binds to pathogenic bacteria and prevents their attachment?
Tamm-Horsfall protein (THP)
Which type of antibodies are effectively achieved in the genitourinary tract, resulting in high levels in the lumen?
IgA
What is the role of Tamm-Horsfall protein in genitourinary tract immunity?
It inhibits the growth of commensal bacteria
How do commensal microorganisms contribute to the normal immune responses in the genitourinary system?
By competing with pathogenic microorganisms for nutrients and attachment sites
What are the characteristics of intra-epithelial $ ext{gamma} ext{ extbf{d}}$T lymphocytes in the mucosal system?
They recognize lipid antigens presented by CD1 molecules
How does the genitourinary tract utilize mucosal immunity to prevent infections?
By producing antimicrobial peptides and secretory IgA antibodies
What is the approximate surface area of the adult respiratory tract?
160m2
Which of the following is NOT a non-specific (Innate) physical defense mechanism of the respiratory tract?
Cough reflex
What is the role of the respiratory tract's defense system according to the text?
To ensure normal physiological function while eliminating dangerous materials
Why is the respiratory system considered the most exposed mucosal surface according to the text?
Due to its constant exposure to inhaled air laden with microorganisms
What is the main role of mucus in respiratory mucosal immunity?
To trap and destroy microorganisms
Which cells in the respiratory tract produce β-defensins that promote bacterial lysis and are chemotactic for leukocytes?
Epithelial cells
What is the function of surfactant proteins A & D in respiratory mucosal immunity?
To trap microorganisms
What is the most common cause of disease in humans related to the respiratory tract?
Respiratory tract infection
What is the main role of mucus in the respiratory tract's mucosal surfaces?
To form a physical barrier against pathogens
Which component of mucus is responsible for forming the sticky layer that traps microorganisms in the respiratory tract?
Mucins
What is the primary function of the respiratory system in handling the challenges posed by the air we breathe?
Trapping microorganisms and preventing their attachment to epithelial cells
How does the respiratory system contribute to the body's defense against microorganisms and irritants in the air we breathe?
By secreting mucus to trap microorganisms and prevent their attachment to epithelial cells
What is the result of prolonged exposure to lipopolysaccharide or lipotechoic acid?
Down-regulation of TLR expression
What is the role of Toll-interacting protein (TOLLIP) in the immune response?
Inhibition of TLR-mediated activation
What is the purpose of the down-regulation of TLR expression due to prolonged exposure to lipopolysaccharide or lipotechoic acid?
To inhibit TLR-mediated activation of immune responses
Which factor provides additional signals to drive an effective immune response against pathogens?
Pathogen-produced factors
What is the delicate balancing act mentioned in the text primarily concerned with?
Ensuring tolerance to food antigens and destroying pathogens
How does antigen processing and presentation contribute to mucosal immunity?
It induces a state of tolerance to food antigens and ensures pathogen destruction
What is the main role of IgM, IgG, and IgA in the lumen of the mucosal system?
Supplying antibodies that protect the lumen
How does the immune response contribute to disease processes according to the text?
Through over-activation, lack of regulation, or inappropriate inflammatory response
What is the primary function of intestinal microbiota in the immune system?
Competing with pathogens for inhibition
Excessive use of antibiotics can lead to disease due to the growth of opportunistic organisms. Which of the following is a likely consequence of this scenario?
Loss of tolerance to endogenous bacteria
Which component synthesized by intestinal microbiota is responsible for competitive inhibition of pathogens?
Antimicrobial peptides
What is the consequence of the excessive use of antibiotics in relation to Clostridium difficile growth?
Promotion of pseudomembranous enterocolitis
Which process is NOT influenced by the presence of normal flora in the gastrointestinal tract?
Peristalsis for waste expulsion
What is the primary role of Toll-like receptors present on mucosal epithelium in the intestine?
Upregulation of cytokine production
Study Notes
- Mucosal surfaces are named for the presence of mucus, which is a protective layer made of glycoproteins called mucins.
- Respiratory, gastrointestinal, and genitourinary systems are the major portals of entry for microorganisms and have distinct mechanisms for physical, chemical, and biological defense.
- Respiratory system: largest mucosal surface, exposed to air laden with microorganisms, pollutants, and irritants; defense mechanisms include sneeze/cough reflex, mucus secretions, and epithelial cell secretions.
- Mucus secretions: produced by goblet cells, provide physical and chemical barriers, contain antibodies (sIgA, IgM), and trap microorganisms.
- Epithelial cells: form a barrier function, prevent attachment of microorganisms, and secrete antimicrobial peptides (β-defensins, cathelicidins, surfactant proteins A & D).
- Gastrointestinal system: largest and most complex mucosal system, home to a large number of microorganisms, tolerates resident microbes while eliminating pathogens, mechanisms include TLR expression, TOLLIP expression, and immunosuppressive factors.
- Genitourinary system: includes reproductive and excretory organs, immune system must protect mother and fetus during pregnancy.
- Mucosal defense: physical (epithelial cells, nasal hairs), chemical (mucus, antimicrobial peptides), and biological (cells and molecules) components.
- Innate immune defense of mucosal system: structures, cells, and molecules that contribute to defense against microorganisms.
- Role of commensal microorganisms in development and maintenance of normal immune responses.
- Relationships between immune inductive sites and immune soluble sites of the mucosal system.
- Pathways of antigen uptake from intestinal lumen: Peyer's patches, M cells, and epithelial cells.
- Tolerance induction: mechanisms include T regulatory cells, IL-10, TGF-β, and increased TOLLIP expression.
- Intra-epithelial γδT lymphocytes: function in mucosal system.
- Tamm-Horsfall protein: role in genitourinary tract immunity.
- Mucosal immunity: protects host from dangerous materials while maintaining normal physiological function.
- Disorders that may arise due to a failure of effective innate or adaptive mucosal defense include Sjogren’s Syndrome, Zollinger-Ellison, and Crohn’s disease.
Explore the role of mucosal surfaces in protecting the respiratory tract from pathogens and microorganisms. Learn about the composition of mucus and its function in trapping and preventing the attachment of harmful agents to the epithelial cells.
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