Host-Microbe Interactions Quiz

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Questions and Answers

Which of the following is an example of a communicable infectious disease?

  • Tetanus
  • Tooth decay
  • Botulism
  • Chickenpox (correct)

Noninfectious diseases can be caused by infectious agents.

False (B)

What is the role of normal microflora in the human body?

Competition for space and nutrients, and antagonism using bacteriocins.

An __________ is an after effect that remains after recovery from a disease.

<p>sequela</p> Signup and view all the answers

Match the types of infectious diseases with their descriptions:

<p>Acute = Rapid development and resolution Chronic = Slow development over a long time period Subacute = Intermediate between acute and chronic Latent = Inactive for a period but can reactivate</p> Signup and view all the answers

What do transferrins in the blood bind to?

<p>Iron (D)</p> Signup and view all the answers

Bacteriocins are substances produced by bacteria to inhibit the growth of other bacteria.

<p>True (A)</p> Signup and view all the answers

What is the main characteristic of a chronic infectious disease?

<p>It has a slow development and persists over a long time period.</p> Signup and view all the answers

What characterizes a local infection?

<p>It is limited to a small area of the body. (A)</p> Signup and view all the answers

A primary infection can be followed directly by another primary infection.

<p>False (B)</p> Signup and view all the answers

What is the term for an infection that produces few or no symptoms?

<p>subclinical infection</p> Signup and view all the answers

The ________ phase is characterized by the presence of initial symptoms after the incubation period.

<p>prodromal</p> Signup and view all the answers

Which of the following is an example of a systemic infection?

<p>Measles (B)</p> Signup and view all the answers

Match the following terms with their definitions:

<p>Incubation period = Time from exposure to first symptoms Decline phase = Decreasing symptoms after illness peak Convalescence period = Recovery phase after illness Invasive phase = Period of intense symptoms</p> Signup and view all the answers

What is the role of sebum on the skin?

<p>To lower pH and contain fatty acids (C)</p> Signup and view all the answers

Superinfections can only occur in the presence of primary infections.

<p>True (A)</p> Signup and view all the answers

The ________ phase of infectious disease is when the illness reaches its highest intensity.

<p>acme</p> Signup and view all the answers

Specific host defences respond immediately when an invader is detected.

<p>False (B)</p> Signup and view all the answers

What is immunological memory?

<p>The ability of immune cells to remember a specific antigen for faster and more effective responses in future encounters.</p> Signup and view all the answers

The skin serves as a __________ barrier to infection.

<p>physical</p> Signup and view all the answers

Match the following immune responses with their characteristics:

<p>Nonspecific Defences = Rapid response, lacks specificity Specific Defences = Slower response, has memory Physical Defences = Includes skin and mucous membranes Biochemical Defences = Involves pH and enzymes like lysozyme</p> Signup and view all the answers

Which of the following is NOT a movement that helps in flushing out potential pathogens?

<p>Swimming (D)</p> Signup and view all the answers

Cilia in the respiratory tract act to trap and expel pathogens.

<p>True (A)</p> Signup and view all the answers

What is the purpose of flushing actions like urine and tears?

<p>To help remove pathogens and prevent infections.</p> Signup and view all the answers

Flashcards

Gastric Acid

A strong acid produced in the stomach that has a low pH, helping to digest food and kill pathogens.

Transferrins

Iron-binding proteins found in the blood that help transport iron and are part of the immune defense.

Normal Microflora

Beneficial bacteria in the body that compete for space and nutrients, and provide protection against pathogens.

Bacteriocins

Antimicrobial peptides produced by bacteria that inhibit the growth of similar or closely related bacterial strains.

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Infectious Disease

An illness caused by infectious agents, such as bacteria, viruses, or parasites.

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Communicable Diseases

Infectious diseases that can be spread from one host to another, like chickenpox.

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Acute Infection

An infectious disease that appears suddenly and lasts a short time, like a cold.

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Chronic Infection

An infectious disease that develops slowly and lasts a long time, such as tuberculosis.

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Local Infection

An infection limited to a small area of the body, like boils or bladder infections.

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Systemic Infection

An infection that spreads widely throughout the body, such as measles or typhoid fever.

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Primary Infection

The initial infection that occurs in a host.

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Secondary Infection

An infection that follows a primary infection, often opportunistic.

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Incubation Period

The time after infection begins but before symptoms appear.

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Prodromal Phase

The stage with initial symptoms that occur before the full illness develops.

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Invasive Phase

The stage where the illness is at its most intense, also known as Acme.

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Convalescence Period

The recovery stage after an illness, where symptoms subside.

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Immune system

The body's defense system against infections and diseases.

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Nonspecific Defenses

Innate defenses that provide immediate protection against a wide range of invaders.

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Specific Defenses

Adaptive defenses that target specific pathogens and have immunological memory.

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Immunological memory

The ability of immune cells to remember past infections and respond quicker.

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Physical Defenses

Anatomical barriers like skin and mucous membranes that protect against infections.

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Mucous Membranes

Tissues that line the respiratory, digestive, and urogenital systems providing defense.

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Flushing actions

Natural actions like urine and tears that help remove pathogens from the body.

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Biochemical Defenses

Chemical barriers (like low pH and lysozyme) that hinder pathogen growth on skin.

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Study Notes

Host Microbe Interactions

  • Host-microbe interactions are complex relationships between organisms.
  • The immune system protects against infection.

Why Don't We Get Sick All the Time?

  • The immune system defends against infections.

Host Defenses

  • The immune system uses innate and adaptive immunity to combat pathogens.

Innate Immunity

  • First line of defense
  • Includes physical and physiological barriers (skin, mucous membranes, cilia, body temperature, pH).
  • Non-specific defenses.
  • Cells like neutrophils, macrophages, dendritic cells and natural killer cells are involved.

Adaptive Immunity

  • Second line of defense
  • Specific host defenses
  • Includes cells like T helper cells, cytotoxic T cells, naïve B cells, and plasma cells.
  • Develops antibodies (memory) to fight specific pathogens that have been encountered before.

Factors leading to Illness

  • Clostridium tetani produces exotoxin that causes tetanus.
  • A puncture wound from a dirty nail can introduce this bacterium, which in turn produces the toxin.

Outcomes of Host Defenses

  • Immune responses involve the body reacting to pathogens and infections.
  • Different outcomes are possible—no apparent illness, illness that resolves, and intervention.

Host Defenses - How Do They Work?

  • The body's immune system combats different infections based on the immune response.

Overview of Non-Specific Host Defenses

  • Innate defenses lack specificity and act rapidly.
  • Example: skin and mucous membranes provide a physical barrier.
  • Adaptive defenses respond to specific invaders and take longer to work.
  • Possess "memory" to respond to previous encounters more effectively (faster and greater magnitude of response).

Physical (Anatomical Defenses)

  • Skin: Physical barrier preventing infection entry.
  • Mucous Membranes: Physical defenses lining respiratory, digestive, and urogenital systems; mucous traps bacteria, preventing attachment.
  • Flushing: Urine, sweat, tears, and saliva wash pathogens away.
  • Respiratory Tract: Cilia, coughing, and sneezing remove pathogens.

Biochemical Defense Tactics

  • Skin: Low pH, high salt, sebum (fatty acids), and lysozyme (enzyme) inhibit pathogen growth and cause bacterial lysis.
  • Gastrointestinal Tract: Gastric acid (low pH) inhibits pathogen growth. Transferrins (iron-binding proteins) limit pathogen availability.

Normal Microflora

  • Normal microflora (microorganisms normally present) exist in various body locations.
  • They compete for resources (space, nutrients), preventing pathogen colonization.
  • Produce bacteriocins (toxic proteins).

Specific Immunity & Antibodies

  • Antibodies bind to pathogens, preventing infection by blocking receptor binding or stimulating phagocytosis.

Infectious Disease Terminology

  • Differentiates between infectious and non-infectious illnesses.
  • Infectious diseases are caused by infectious agents.
  • Non-infectious diseases are caused by other factors besides infections.

Communicable vs. Noncommunicable Infections

  • Communicable infections spread from one host to another. Contagious infections spread easily between hosts (ex. chickenpox).
  • Noncommunicable infections use alternate routes to spread, such as ingestion (botulism).

Signs, Symptoms, and Sequelae

  • Signs: Observable disease characteristics (rash, swelling).
  • Symptoms: Felt characteristics of a disease (pain, nausea).
  • Sequelae: Long-term aftereffects of disease (permanent damage after an infection).

Types of Infectious Diseases

  • Acute: Rapid onset (colds).
  • Chronic: Long-lasting (tuberculosis).
  • Subacute: Intermediate between acute and chronic.
  • Latent: Periods of dormancy before and between active disease phases (herpes simplex virus).

Types of Infections

  • Local: Limited to a specific area (boil, bladder infection).
  • Systemic: Throughout the body via the bloodstream or other systems (measles, typhoid fever).

Primary and Secondary Infections

  • Primary infection: Initial infection.
  • Secondary infection: Occurs due to a weakened immune system after a primary infection (or another infection). Opportunistic infections are secondary infections.

Stages of Infectious Diseases

  • Including incubation, prodromal, and acme phases, as well as convalescent and decline periods.
  • Stages vary among different pathogens.

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