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)
What are the benefits that normal flora get from eukaryotes?
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What are factors that affect normal flora?
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Why are different bacteria found at different locations?
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Why do skin flora bacteria stay on skin?
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Give some examples of skin characteristics.
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Where are flora bacteria found on the skin?
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How do lungs remain sterile?
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The oral cavity is sterile at birth.
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When does the oral cavity become unsterile and bacteria colonize?
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What is dental plaque?
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The gastrointestinal tract is sterile at birth.
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When does the gastrointestinal tract change from being sterile to unsterile?
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What happens to bacteria at the esophagus area?
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What is the pH of your stomach?
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What is one of the bacteria that live in your small intestines?
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What are probiotic bacteria and where are they found?
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What are the benefits of probiotic bacteria?
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In the genitourinary tract, what parts are sterile vs normal flora?
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How do lactobacilli prevent pathogens from causing vaginal infections?
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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.
