40 Questions
What is the mode of transmission of R.prowazekii from animals to humans?
Indirect through vectors
What is the function of goblet cells in the mucous membrane?
Mucus production and provision of antibacterial substances
What is the function of lactoferrin in mucosal defense?
Provision of antibacterial substances
What is the pH level of the stomach that helps in mucosal defense?
Low pH
What is the role of lysozyme in mucosal defense?
Provision of antibacterial substances
What is the function of mucosal linings in the nasopharynx?
Secretion of antibacterial substances
What is the mode of transmission of epidemic typhus?
Indirect through vectors
What is the function of lactoperoxidase in mucosal defense?
Provision of antibacterial substances
What is the primary source of microorganisms in an infant's GI tract at birth?
Placental microbiome
What is the main factor that determines the type of resident microbiota on the skin?
Anatomic location
Which of the following is NOT a normal location for microorganisms to reside?
Blood
What is the primary reason why certain microorganisms are attracted to the skin?
Because of the presence of moisture and warmth
What is the role of harmless and helpful microbes on the skin?
Taking up residence on the skin
What is unique about the microbiota of the middle ear and inner ear?
They are sterile
What is the main difference between resident microbiota and transient microbiota?
Resident microbiota are permanent, while transient microbiota are temporary
What is the role of other microbes on the skin?
Producing toxic substances
What is the first step of developing an infection and disease?
Colonization
What is the primary function of phagocytic white blood cells?
To engulf and digest foreign particles and microorganisms
What is the role of the complement system?
To enhance phagocytosis
What is the primary function of the coagulation system?
To wall off the site of infection
What is the role of normal microbiota?
To provide a physical barrier against pathogens
What is the result of overuse of antibiotics?
Disruption of skin and mucosal surfaces
What is the role of fever in the host response to infection?
To regulate the body's temperature
What is the third line of defense against infection?
Specialized lymphocytes and antibodies
What is the primary function of NK cells?
Recognizing and destroying tumor or viral-infected cells
What is the primary difference between endotoxin and exotoxin?
Endotoxin is released when Gram-negative bacteria are destroyed, while exotoxin is released from living Gram-positive bacteria
What is the role of suppressor T cells?
Regulating the response of T and B cells
What is the definition of a pathogen?
A microorganism that causes infection and disease
What is the outcome of an infectious disease?
The microorganism grows and multiplies, causing damage to the host
What is the difference between colonization and infection?
Colonization is when microorganisms grow and multiply, while infection is when the microorganisms cause disease
What is the function of T lymphocytes?
Helper and cytotoxic functions
What is the characteristic of B lymphocytes?
They produce antibodies to combat microorganisms
What is the primary function of cytokines in the body's defense mechanisms?
To enhance the activities of different cells in nonspecific and specific defensive responses
What is the primary cause of pain during inflammation?
Tissue damage and pressure from increased flow of fluid and cells
What is the specific function of helper T cells in the body's defense mechanisms?
To enhance the proliferation and differentiation of B cells
What is the primary characteristic of specific immunity?
Specificity
What is the primary function of B cells in the body's defense mechanisms?
To produce antibodies in response to the presence of foreign molecules
What is the primary function of cytotoxic T cells in the body's defense mechanisms?
To recognize and destroy targets or direct contact through the recognition and destruction of antigen-presenting cells
What is the primary characteristic of antibody-mediated immunity?
Specificity
What is the primary role of macrophages in the body's defense mechanisms?
To ingest and destroy pathogens
Study Notes
Microorganisms in the Infant GI Tract
- Microorganisms are present in the infant GI tract at birth, likely acquired from the placental microbiome
- Harmless and helpful microbes take up residence on the baby's skin, at all body openings, and on mucous membranes that line the digestive tract and genitourinary (GU) tract
Factors Affecting Microorganisms on the Skin
- Anatomic location
- Amount of moisture present
- pH
- Temperature
- Salinity
- Presence of chemical wastes, such as urea and fatty acids
- Presence of other microbes, which may produce toxic substances
Microbiota of the Ears and Eyes
- The middle ear and inner ear are usually sterile, whereas the outer ear and the auditory canal contain the same types of microbes as the skin
- Conjunctival epithelium covering the eyes
Mucous Membrane Structures
- Rapid sloughing of mucosal cells
- Tight intracellular junctions
- Goblet cells produce mucus and provide antibacterial substances to the mucosal surface, including lysozyme, lactoferrin, and lactoperoxidase
Microorganism's Perspective
- Colonization: persistent survival of microorganisms on the surface of the human body, which can be mutually beneficial or the first step of developing infection and disease
- Sterile body sites include blood, CSF, and urinary bladder
Skin Microbiota
- P.acnes, S.epidermidis, viridans streptococci, and Enterococcus
- Mouth and oral cavity: viridans streptococci, S.epidermidis, and Neisseria species
- Colon: Bacteroides, Lactobacillus, Clostridium, Eubacterium, and E. coli
- Urethra: Diptheroids, alpha and gamma hemolytic streptococci, and S.epidermidis
Microorganisms Entry, Invasion, and Dissemination
- Factors contributing to disruption of skin and mucosal surfaces include:
- Trauma
- Inhalation
- Implantation of medical devices
- Overuse of antibiotics
- Nonspecific resistance:
- First line of defense: intact skin, mucous membranes, and their secretions, and normal microbiota
- Second line of defense: phagocytic white blood cells, inflammation, fever, and antimicrobial substances
- Specific resistance: specialized lymphocytes (B cells and T cells) and antibodies
Nonspecific Responses
- Phagocytosis: neutrophils and macrophages
- Biochemical responses:
- Complement system
- Coagulation system
- Cytokines
Inflammation
- Swelling: increased blood flow
- Redness: vasodilation of blood vessels
- Heat: increased temperature of affected tissue
- Pain: tissue damage and pressure from increased flow of fluid and cells
Specific Immunity
- Characteristics: specificity and memory
- Antibody-mediated immunity: produced by B cells in response to the presence of foreign molecules (antigens)
- Cell-mediated immunity: T lymphocytes (helper and cytotoxic) and NK cells
Bacterial Toxins
- Two general types: endotoxin and exotoxin
- Endotoxin: released when Gram-negative bacterial cell is destroyed, e.g., E. coli, V. cholerae, S. typhi
- Exotoxin: released from living Gram-positive bacteria, e.g., B. cereus, S. aureus, S. pyogenes
This quiz covers the factors that affect the number and variety of microorganisms in infants, including placental microbiome, anatomic location, amount of moisture, and pH.
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