Pathophysiology: Tissue Responses to Injury and Infection

Comprehensive practice flashcards covering pathophysiology, epidemiology, immunology, and infectious diseases as discussed in the lecture notes.

What are the two specific drug-resistant pathogens mentioned as a rising concern in the transcript?

Malaria, TB, and pneumonias are developing drug resistance, and MRSA is becoming resistant to vancomycin.

Which specific immune cells are responsible for surveying for cancer cells with abnormal proteins?

Cytotoxic T cells, natural killer cells, and macrophages.

How is incidence defined in epidemiology?

The development of new cases of a disease, expressed as the ratio of the number of subjects developing disease over a specific period divided by the number of subjects followed.

What is the formula for calculating prevalence?

$$\text{Prevalence} = \text{incidence rate} \times \text{average disease duration}$$

How does continuous stress due to social determinants of health affect physiological systems?

It weakens resistance to disease and disrupts the hormone, metabolic, and immune systems.

What is the definition of communicability?

The ability of a microorganism to spread from one individual to others and cause disease.

Contrast the virulence of measles and rabies according to the transcript.

Measles is low virulence, while rabies is highly virulent.

What does ID50 represent in microbiology?

The estimated number of organisms or viruses required to produce infection in $50\%$ of a population.

Define mutualism in the context of human-microorganism relationships.

A relationship that benefits both the human and the microorganism.

What is a fomite?

An inanimate object contaminated with infectious agents.

What is vertical transmission?

Transmission from mother to child across the placenta, during delivery, or through breastfeeding.

Describe the prodromal stage of infection.

The occurrence of initial symptoms which are mild, such as a feeling of discomfort and fatigue.

What are the characteristics of Gram-negative bacteria regarding staining and composition?

They stain light pink and contain lipopolysaccharide ($LPS$).

How do biofilms contribute to bacterial survival?

Bacteria excrete a matrix that protects them from immune cells and antibiotics; they are associated with chronic infections and poor wound healing.

What specific inflammatory mediators are released when endotoxins stimulate cell lysis?

Tumor necrosis factor, $IL-1$, $IL-6$, $IL-8$, and platelet activating factors.

What is the result of horizontal gene transfer through conjugation?

Two bacteria fuse together to transfer genes, creating hybrid bacteria with increased virulence or antibiotic resistance.

What are the stages of viral replication in order?

1. Recognition and attachment 2. Penetration 3. Uncoating 4. Replication 5. Translation 6. Assembly 7. Release.

Differentiate between antigenic drift and antigenic shift.

Antigetic drift involves minor mutations in the virus genome (e.g., yearly flu), while antigenic shift occurs when two or more viruses combine to form a new strain (e.g., H1N1 pandemic).

What is the difference between bactericidal and bacteriostatic antibiotics?

Bactericidal antibiotics kill the bacteria, while bacteriostatic antibiotics inhibit growth until the immune system destroys them.

What are toxoid vaccines?

Vaccines that use parts of microbial toxins to induce an immune response.

Define passive immunity and provide an example from the notes.

Preformed antibodies are given to an individual, such as using human immunoglobulin for Hepatitis A and B.

What constitutes the second line of defense in the immune system?

The inflammatory response, which is an immediate, non-specific response to tissue injury or infection.

Give examples of biochemical barriers synthesized by epithelial cells.

Mucus, sweat, saliva, tears, and earwax.

What occurs during dysbiosis of the microbiome?

Negative changes in the microbiome linked to diseases like obesity, diabetes, and mental health disorders.

How do cytokines and chemokines differ in function during inflammation?

Cytokines regulate the activity of immune cells, while chemokines function to recruit additional immune cells.

What is the role of Toll-like receptors ($TLRs$)?

They are pattern recognition receptors on immune cells that recognize pathogen-associated molecular patterns ($PAMPs$) of pathogens.

What substances are synthesized and released by mast cells besides histamine?

Leukotrienes, prostaglandins, platelet activating factor, and growth factor.

Which cytokine is specifically identified as a pyrogen?

$IL-1$.

What are Neutrophil Extracellular Traps ($NETs$)?

Unraveled DNA extruded into the extracellular space to capture and neutralize microorganisms.

What are the functions of $C3$ and $C5$ in the complement system?

$C3$ acts as an opsonin to coat bacteria for phagocytosis; $C5$ acts as a chemotactic factor to attract leukocytes.

What causes the local manifestations of heat and redness in acute inflammation?

Vasodilation, which increases blood flow to the area, primarily caused by histamine.

What is a granuloma?

A tumor-like mass found at the site of chronic inflammation that functions to wall off and isolate an infected area.

Contrast the origins of T and B lymphocytes.

T lymphocytes stem from the thymus, and B lymphocytes stem from the bone marrow.

What are haptens?

Small molecules that are too small to induce an immune response themselves but combine with larger carrier molecules to become immunogenic.

Which MHC molecule is responsible for presenting endogenous antigens to T-cytotoxic ($CD8$) cells?

$MHC\,I$.

Which class of antibody is the only one to cross the placenta during pregnancy?

$IgG$.

What is the definitive diagnostic threshold for AIDS according to $CD4+$ cell count?

Fewer than $200\,CD4+\text{ per } \mu L$ of blood.

Define sensitization as it relates to hypersensitivity reactions.

The initial exposure to an antigen that primes the immune system with antibodies or memory T cells, requiring subsequent exposure to trigger symptoms.

What characterizes Type III hypersensitivity?

The production of antigen-antibody complexes that get deposited in blood vessels or tissues, causing damage via complement activation.

Why is Type IV hypersensitivity called 'delayed'?

It takes $48\text{--}72\text{ hours}$ for inflammation to develop as it requires antigen presentation to memory T cells.

Identify three enzymes HIV uses for replication.

Reverse transcriptase, integrase, and protease.

How are pyrogenic cytokines believed to cause a fever?

They act on the hypothalamus to raise the thermal set point, inducing heat production and conservation.

What characterizes cachexia in chronic illness?

Complex metabolic disorder involving muscle wasting and atrophy, often mediated by pro-inflammatory cytokines like $TNF\text{-}\\alpha$ and $IL-1$.

Differentiate between microbiota and the microbiome.

Microbiota is the collection of microorganisms associated with the human body; the microbiome is the collection of genes expressed by those microorganisms.

How does DNA packaging affect gene expression in epigenetics?

Tightly packaged DNA ($\text{heterochromatin}$) decreases gene expression, while loosely packaged DNA ($\text{euchromatin}$) increases it.

What is a zoonotic infection?

An infectious disease transmitted between humans and animals, such as those originating from a spillover event.

What is the primary reservoir for the Ebola virus?

Fruit bats.

Which receptor does the SARS-CoV-2 spike protein bind to in host airways?

Angiotensin-converting enzyme 2 ($ACE2$).

What is the definition of an epitope?

The specific area on an antigen recognized by an antibody using a lock and key mechanism.

Name three protective plasma proteins produced during the acute phase response.

$CRP$, fibrinogen, and ferritin.