Module 9: 1.Patho: Define the factors influencing infection. Flashcards
What are some factors that can cause damage to the human body?
Factors include sunlight, pollutants, physical trauma, infectious agents like viruses and bacteria, and internal factors like cancer.
How can damage impact the body?
Damage can range from affecting a single cell to multiple cells, tissues, or organs, potentially leading to disease and, in severe cases, death.
Why does the body need defense mechanisms?
The body requires defense mechanisms to protect against the various factors that can cause damage, ensuring its survival and well-being.
What is innate immunity?
Innate immunity, also called natural immunity, comprises physical and biochemical barriers and inflammation, which protect the body from injury and infection.
What is the role of physical and biochemical barriers in innate immunity?
These barriers are the first line of defense, present from birth, to prevent damage and thwart infections by harmful microorganisms. They can also host helpful microorganisms known as the “normal flora.”
What happens if an injurious agent breaches the surface barriers?
If an injurious agent penetrates the surface barriers, the second line of defense, the inflammatory response, is activated to protect the body from further injury, prevent infection, and promote healing.
Describe the nature of the inflammatory response.
The inflammatory response is a rapid and relatively nonspecific reaction to different types of tissue damage, initiated regardless of the specific cause. It aims to protect the body.
What is the third line of defense in the body’s immune system?
The third line of defense is adaptive (acquired) immunity, also known as specific immunity.
How does adaptive immunity differ from innate immunity in terms of speed and specificity?
Adaptive immunity is slower and more specific, targeting particular invading microorganisms.
What is the role of “memory” in adaptive immunity?
Memory in adaptive immunity results in a faster response upon re-exposure to the same microorganism.
What are the three levels of human defenses?
The three levels of human defenses are Barriers, Innate Immunity, and Adaptive (Acquired) Immunity.
What is the primary role of Barriers in the defense system?
Barriers serve as the first line of defense, providing physical and biochemical protections, including skin, mucous membranes, and secretory molecules.
What characterizes the second line of defense, Innate Immunity?
Innate Immunity represents the second line of defense and involves immediate responses like inflammation, along with cells such as mast cells, neutrophils, and macrophages.
How is Adaptive (Acquired) Immunity different from the other defense levels in terms of specificity?
While Barriers and Innate Immunity have broad specificity, Adaptive (Acquired) Immunity is highly specific, targeting specific antigens.
What is the role of memory in the immune system?
While Barriers and Innate Immunity have broad specificity, Adaptive (Acquired) Immunity is highly specific, targeting specific antigens.
What is the role of memory in the immune system?
Adaptive immunity involves specific immunological memory, allowing for a faster and more efficient response upon re-exposure to the same antigen.
Which cells are involved in the third line of defense, Adaptive Immunity?
T cells, B cells, macrophages, and dendritic cells are among the cells involved in Adaptive (Acquired) Immunity.
What are some active molecules used in human defenses?
Active molecules include defensins, complement, antibodies, and various cytokines.
How does each level of defense provide protection?
Barriers offer protection through physical and biochemical mechanisms, Innate Immunity uses inflammation and immune cells, while Adaptive (Acquired) Immunity employs activated T and B cells, antibodies, and cytokines for protection.
What are the external physical barriers in the body?
The external physical barriers consist of tightly associated epithelial cells in the skin and linings of the gastrointestinal, genitourinary, and respiratory tracts.
How does the body remove pathogens attempting to breach these barriers?
Mechanical processes like coughing, sneezing, vomiting, flushing by urine, and the continual replacement of dead epithelial cells remove pathogens.
What is the role of mucus and cilia in the upper respiratory tract?
Epithelial cells in the upper respiratory tract produce mucus and have hair-like cilia that trap and move pathogens upward, leading to their expulsion through coughing and sneezing.
How do low temperatures and low pH levels contribute to defense against microorganisms?
Low temperatures and low pH levels on the skin and in the stomach generally inhibit the growth of microorganisms, as most microorganisms require higher temperatures and near-neutral pH for efficient growth.
What protective substances are secreted by epithelial cells to guard against infection?
Epithelial cells secrete mucus, perspiration, saliva, tears, and earwax.
How do perspiration, tears, and saliva combat Gram-positive bacteria?
Perspiration, tears, and saliva contain lysozyme, an enzyme that attacks the cell walls of Gram-positive bacteria.
What substances are secreted by sebaceous glands in the skin, and what do they do?
Sebaceous glands secrete fatty acids and lactic acid, which have bactericidal properties against bacteria and fungi.
How does the pH environment created by glandular secretions affect bacteria?
Glandular secretions create an acidic and inhospitable environment with a pH range of 3 to 5, which is hostile to most bacteria.
What are antimicrobial peptides, and where are they found?
Antimicrobial peptides are small molecules that kill or inhibit the growth of disease-causing bacteria, fungi, and viruses. They are found in epithelial cell secretions.
How do cathelicidins work against bacteria, and where are they produced?
Cathelicidins disrupt bacteria by inserting into their cholesterol-free cell membranes. They are produced in epithelial cells of the skin, gut, urinary tract, and respiratory tract.
When is cathelicidin released, and by which cells?
Neutrophils, mast cells, and monocytes store cathelicidin and release it during inflammation.
What are the two subtypes of human defensins, and how do they differ in activation?
Human defensins come in two subtypes: α-defensins and β-defensins. α-defensins require activation by proteolytic enzymes, while β-defensins do not.
How do α-defensins work to combat bacteria, and where are they found?
α-defensins work with neutrophils to kill bacteria. They are also present in Paneth cells in the small intestine, protecting against disease-causing microorganisms.
Where are β-defensins primarily located, and what infections can they potentially guard against?
β-defensins are abundant in epithelial cells lining the respiratory, urinary, and intestinal tracts, as well as in the skin. They may help protect against infections like adenovirus (common cold) and human immunodeficiency virus (HIV).
What is the role of antimicrobial peptides in activating the body’s defense systems?
Both α-defensins and β-defensins can activate cells involved in subsequent levels of defense, including innate and acquired immunity.
What are collectins, and what do they do in the body?
Collectins are glycoproteins produced by the lung, including surfactant proteins A-D and mannose-binding lectin. They interact with carbohydrates on the surfaces of pathogenic microorganisms and aid macrophages in recognizing and eliminating these microorganisms.
How does mannose-binding lectin (MBL) contribute to immune defense?
MBL is adept at recognizing a common sugar on microorganism surfaces. It activates the complement plasma protein system, resulting in damage to bacteria or increased recognition by macrophages.
What is the normal microbiome, and where is it found in the body?
The normal microbiome consists of various microorganisms and is located on the body’s surfaces, including the skin, mucous membranes, GI tracts, respiratory tract, urethra, and vagina.
Do the microorganisms in the microbiome typically cause diseases?
No, the microorganisms in the microbiome do not typically cause diseases.
How would you describe the relationship between the microbiome and humans?
The relationship between the microbiome and humans can be commensal, where one benefits without affecting the other, or mutualistic, benefiting both.
What happens in the lower gut shortly after birth?
The lower gut is initially sterile at birth, but it quickly begins to get colonized by bacteria. The number, diversity, and concentration of these microorganisms increase progressively during the first year of life.
What are some of the benefits provided by the normal microbiome in the GI tract?
The benefits include the production of digestive enzymes, generation of essential metabolites like vitamins, and the release of antibacterial factors to prevent colonization by harmful microorganisms.
How do some members of the normal microbiome in the colon inhibit the growth of pathogenic microorganisms?
They produce toxic chemicals and proteins, compete for nutrients with pathogens, and block their attachment to the epithelium, a crucial step in the infection process.
How does the normal microbiome in the gut influence the adaptive immune system?
It promotes the growth of gut-associated lymphoid tissue, where most adaptive immune cells reside, and contributes to the development of both local and systemic adaptive immunity.
What is the role of GI bacteria in the brain-gut axis, and how does it impact various aspects of human health?
GI bacteria play a role in modulating cognitive function, behavior, pain, and stress responses through their influence on the brain-gut axis.
What can prolonged use of broad-spectrum antibiotics do to the normal microbiome?
Prolonged antibiotic use can disrupt the normal microbiome, reducing its protective activity and promoting overgrowth of harmful microorganisms.
What are some of the potential consequences of microbiome disruption in the intestine?
Disruption of the microbiome can lead to the overgrowth of Candida albicans and Clostridium difficile, potentially causing conditions like pseudomembranous colitis.
What is the role of Lactobacillus in the normal GI and vaginal microbiome of healthy women?
Lactobacillus produces protective chemicals like hydrogen peroxide, lactic acid, and bacteriocins, which help prevent infections in the vagina and urinary tract by other microorganisms.
How does prolonged antibiotic treatment affect Lactobacillus colonization and what are the associated risks?
Extended antibiotic use can reduce the presence of Lactobacillus, increasing the risk of urological or vaginal infections, such as vaginosis.
What types of microorganisms are predominantly found on the skin, and what variations exist?
Predominantly, the skin hosts Gram-positive cocci and rods. Specific areas may have variations, and some individuals may also carry yeasts like Candida and Pityrosporum.
What is the typical composition of microorganisms in the nose?
The nose primarily contains Gram-positive cocci and rods. Some individuals may carry pathogenic bacteria like S. aureus and β-hemolytic streptococci.
Describe the complex mix of bacteria found in the mouth.
The mouth hosts a complex mix of bacteria, including several species of streptococci, Actinomyces, lactobacilli, and Haemophilus. Anaerobic bacteria and spirochetes colonize gingival crevices.
What microorganisms are typically present in the colon?
The colon contains a diverse range of microorganisms, including Bacteroides, lactobacilli, clostridia, Salmonella, Shigella, Klebsiella, Proteus, Pseudomonas, enterococci, and other streptococci, bacilli, and Escherichia coli.
Which bacteria are typically found in the distal urethra, and what other microorganisms might be present?
The distal urethra typically contains bacteria found on the skin, such as S. epidermidis and diphtheroids. It may also have lactobacilli and nonpathogenic streptococci.
How does the composition of the vaginal microbiome change with age?
The vaginal microbiome varies with age. In newborns, it’s similar to adults. From 1 month to puberty, S. epidermidis, diphtheroids, E. coli, and streptococci are common. During puberty to menopause, Lactobacillus acidophilus becomes dominant. Postmenopause, it becomes similar to the prepubescent microbiome.
What is the primary purpose of the inflammatory response?
The inflammatory response is designed to limit tissue damage, eliminate infectious microorganisms, initiate adaptive immunity, and promote healing.
What are the four key characteristics of the inflammatory response?
The four key characteristics are: (1) it occurs in tissues with a blood supply, (2) it is activated rapidly (within seconds) after damage occurs, (3) it depends on both cellular and chemical components, and (4) it is nonspecific, responding similarly to various stimuli.
Why does inflammation occur in tissues with a blood supply?
Inflammation occurs in vascularized tissues because they have a blood supply, allowing for a rapid and efficient response to damage or infection.
How quickly does the inflammatory response become activated after tissue damage?
The inflammatory response is activated very rapidly, often within seconds after tissue damage occurs.
What is meant by the nonspecific nature of inflammation?
The nonspecific nature of inflammation means that it responds in a similar way regardless of the type of stimulus or whether exposure to the same stimulus has occurred in the past.
What can activate the inflammatory response in vascularized tissues?
Virtually any injury, including infection, tissue necrosis (e.g., ischemia, trauma, chemical injury), foreign bodies, and immune reactions, can activate the inflammatory response.
What are the cardinal signs of acute inflammation described by Celsus?
The cardinal signs are rubor (redness), calor (heat), tumour (swelling), dolor (pain), and functio laesa (loss of function).
What happens at the microscopic level near the site of injury during inflammation?
Microscopic changes include vasodilation (increased blood vessel size), increased vascular permeability with fluid leakage (edema), and white blood cell adherence and migration through vessel walls.
How does vasodilation contribute to inflammation?
Vasodilation leads to slower blood velocity and increased blood flow at the injury site, contributing to redness and warmth.
What causes the swelling (edema) associated with inflammation?
Increased vascular permeability and fluid leakage out of the vessels cause swelling (edema) at the site of injury.
What are the key components involved in inflammation at the site of injury?
Inflammation involves leukocytes (especially neutrophils), plasma proteins, and various biochemical mediators in the blood and tissues.
How do vascular changes contribute to inflammation?
Vascular changes allow the delivery of leukocytes, plasma proteins, and mediators to the injury site, promoting the inflammatory response.
What role do some chemical mediators play in inflammation?
Some chemical mediators activate pain fibers, contributing to the sensation of pain during inflammation.
How does tissue injury, pain, and swelling collectively affect the body?
Tissue injury, pain, and swelling can lead to a loss of function at the site of inflammation.
What happens to lymphatic vessels during inflammation, and what are the consequences for lymph nodes?
Lymphatic vessels drain extravascular fluid to lymph nodes. Inflammation can lead to lymphangitis in the lymph vessels and lymphadenitis in the nodes, which become hyperplastic, enlarged, and painful.
What are the benefits of inflammation in preventing infection and further damage?
Inflammation prevents infection by invading microorganisms, dilutes bacterial toxins, and activates plasma protein systems to contain and destroy bacteria. Phagocytes (neutrophils, macrophages) eliminate cellular debris and microorganisms.
How does inflammation limit and control the inflammatory process?
Inflammation prevents the spread of the inflammatory response to areas of healthy tissue through the influx of plasma protein systems, plasma enzymes, and cells (e.g., eosinophils).
How does inflammation interact with the adaptive immune system?
Inflammation brings macrophages and lymphocytes to the site, which destroy pathogens, eliciting a more specific immune response.
What is the role of inflammation in preparing the area of injury for healing and repair?
Inflammation removes bacterial products, dead cells, and other inflammatory substances, creating a favorable environment for healing and repair.
How does the drainage of fluid and debris at an inflamed site contribute to the development of acquired immunity?
Fluid and debris are drained by lymphatic vessels, allowing microbial antigens in lymphatic fluid to encounter lymphocytes in the lymph nodes, contributing to acquired immunity.
What are the three key plasma protein systems essential to an effective inflammatory response?
The three key plasma protein systems are the complement system, clotting system, and kinin system.
What is a common characteristic of these plasma protein systems in their inactive forms?
In their inactive forms, these systems comprise multiple proteins, with some being enzymes circulating as proenzymes.
How are the components within these systems activated during inflammation?
Activation of the initial components triggers sequential activation of other components, creating cascades, referred to as the complement cascade, clotting cascade, or kinin cascade.
What may be required for the activation of a specific protein in these systems?
In some cases, activation of a particular protein may require enzymatic cleavage into two differently sized fragments.
