Microbiology Chapter on Normal Flora
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Questions and Answers

What is the definition of normal flora?

The mixture of bacteria normally found at specific body sites without causing disease.

What are areas of the body that are normally sterile?

Lungs, heart, liver, kidneys, bladder, brain.

Interactions between normal flora and host include which of the following? (Select all that apply)

  • Parasitism (correct)
  • Competition
  • Commensalism (correct)
  • Mutualism (correct)

    • What are the benefits that normal flora get from eukaryotes?

    <p>Nutrients, immune system stimulation, exclusion of potential pathogens.</p> Signup and view all the answers

    What are factors that affect normal flora?

    <p>Age, sex, diet, specific tissues.</p> Signup and view all the answers

    Why are different bacteria found at different locations?

    <p>Due to tissue tropism and ligand-mediated interactions.</p> Signup and view all the answers

    Why do skin flora bacteria stay on skin?

    <p>To prevent the growth of pathogenic fungi on skin.</p> Signup and view all the answers

    Give some examples of skin characteristics.

    <p>Skin is mostly dry, has a slightly acidic pH, and a high sodium chloride concentration.</p> Signup and view all the answers

    Where are flora bacteria found on the skin?

    <p>Oily areas behind the ear, forehead; moist areas underarm, inside the elbow, groin; dry areas hands, forearms.</p> Signup and view all the answers

    How do lungs remain sterile?

    <p>Mucus traps bacteria, cilia sweep out trapped bacteria, and lysozyme cells destroy bacteria.</p> Signup and view all the answers

    The oral cavity is sterile at birth.

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

    When does the oral cavity become unsterile and bacteria colonize?

    <p>After first feeding.</p> Signup and view all the answers

    What is dental plaque?

    <p>A biofilm or mass of bacteria that grows on surfaces within the mouth.</p> Signup and view all the answers

    The gastrointestinal tract is sterile at birth.

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

    When does the gastrointestinal tract change from being sterile to unsterile?

    <p>After babies switch to solid food or cow's milk.</p> Signup and view all the answers

    What happens to bacteria at the esophagus area?

    <p>Bacteria are swallowed with food.</p> Signup and view all the answers

    What is the pH of your stomach?

    <p>Acidic, around 2, very acidic.</p> Signup and view all the answers

    What is one of the bacteria that live in your small intestines?

    <p>Coliforms.</p> Signup and view all the answers

    What are probiotic bacteria and where are they found?

    <p>Beneficial bacteria found in high numbers in fermented food.</p> Signup and view all the answers

    What are the benefits of probiotic bacteria?

    <p>Help digest certain foods, prevent pathogens from colonizing, produce essential vitamins.</p> Signup and view all the answers

    In the genitourinary tract, what parts are sterile vs normal flora?

    <p>Sterile = upper urinary tract; normal flora = distal urethra.</p> Signup and view all the answers

    How do lactobacilli prevent pathogens from causing vaginal infections?

    <p>They involve anti-adhesion factors, by-products like hydrogen peroxide, and immune modulation.</p> Signup and view all the answers

    Study Notes

    Normal Flora Overview

    • Normal flora consists of a diverse mixture of bacteria residing on specific body sites without causing disease.
    • The human body contains more bacterial cells than human cells, establishing a symbiotic relationship.

    Sterile Body Areas

    • Sterile regions include lungs, heart, liver, kidneys, bladder, and brain.

    Interactions with Host

    • Normal flora interactions with hosts can involve:
      • Parasitism: Harmful interaction benefiting one party.
      • Commensalism: One organism benefits without affecting the other.
      • Mutualism: Both organisms benefit from the relationship.

    Benefits of Normal Flora

    • Hosts receive:
      • Nutrients and immune system stimulation.
      • Exclusion of potential pathogens, preventing infections.
    • Bacteria gain:
      • Nutrients, stable environments, and means for transport between individuals.

    Factors Influencing Normal Flora

    • Determined by various factors including:
      • Age and sex of the host.
      • Diet and specific tissues or environments in the body.

    Tissue Specificity

    • Different bacteria favor particular tissues due to:
      • Tissue tropism: Preference of certain bacteria for specific tissues.
      • Ligand-mediated interactions influencing adhesion to tissues.

    Skin Flora Function

    • Skin bacteria inhibit pathogenic fungi growth, contributing to protection.

    Skin Characteristics

    • Skin environment is typically:
      • Mostly dry, slightly acidic (pH close to 5).
      • High sodium chloride concentration; some areas may be oily or moist.

    Skin Areas with Flora

    • Bacteria are found in various skin areas:
      • Oily areas like behind the ears and forehead.
      • Moist areas such as underarms, inside elbows, and groin.
      • Dry areas include hands and forearms.

    Respiratory Tract Sterility

    • Lungs remain sterile due to:
      • Mucus trapping bacteria and cilia sweeping them out.
      • Lysozyme enzymes present in the lungs destroying microorganisms.

    Oral Cavity Colonization

    • The oral cavity is sterile at birth but becomes colonized post-first feeding.

    Dental Plaque

    • Defined as a biofilm or mass of bacteria adhering to surfaces in the mouth, contributing to oral health issues.

    Gastrointestinal Tract Sterility

    • Initially sterile at birth, it becomes unsterile after the introduction of solid food and cow's milk.

    Bacterial Presence in Esophagus

    • Bacteria enter the esophagus through food swallowing, aiding in microbial transfer.

    Stomach Acidity

    • Stomach pH is around 2, creating an unfavorable environment for most bacteria.

    Bacteria in Small Intestines

    • Coliforms are an example of bacteria commonly found in the small intestine.

    Probiotic Bacteria

    • Beneficial bacteria located in the gut, found in high quantities in fermented foods.

    Benefits of Probiotics

    • Aid in digestion, prevent colonization by pathogens, and produce essential vitamins.

    Genitourinary Tract Flora

    • Upper urinary tract is sterile, while distal urethra contains normal flora.

    Lactobacilli in Vaginal Health

    • Lactobacilli function to prevent infections through:
      • Anti-adhesion factors, hydrogen peroxide by-products, bacteriocins targeting pathogens, and potential immune signaling effects.

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    Description

    Explore the fascinating world of normal flora in this quiz. Understand the role of these bacteria in human health, their interactions with hosts, and the benefits they provide. Test your knowledge on the factors influencing normal flora and the importance of maintaining a healthy microbiome.

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