Gastrointestinal Tract Micro Flora Quiz

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Questions and Answers

What essential vitamins are produced by the normal flora of the gastrointestinal tract?

Vitamin D and E

Vitamin K and B (correct)

Vitamin A and C

Vitamin B and C

How do gut microbiota help in preventing infections by pathogens?

By increasing intestinal permeability

Through bacterial interference and nutrient depletion (correct)

By enhancing digestive enzyme activity

By producing antibodies against pathogens

What is the role of gnotobiotic animals in research related to gut microbiota?

They are used to study the effects of probiotics.

They illustrate the consequences of an absence of gut flora. (correct)

They have a fully developed immune system.

They provide insights into the effects of standard diets.

What do probiotics aim to treat or prevent?

Dysbiosis and infections Signup and view all the answers

What defines a prebiotic?

A non-digestible ingredient that stimulates specific bacteria growth Signup and view all the answers

Which of the following is NOT a result of gut microbiota activity?

Fermentation of digestible carbohydrates Signup and view all the answers

Which condition can probiotics help treat effectively?

Irritable bowel syndrome (IBS) Signup and view all the answers

What is meant by 'normal microbial flora' in the context of the gastrointestinal tract?

Microorganisms that inhabit the skin and mucous membranes of healthy individuals. Signup and view all the answers

What is a significant characteristic of bacteria in the gut microflora?

They can harm the host if allowed to grow unchecked. Signup and view all the answers

What defines the anatomical distribution of gut microflora?

Presence in the gastrointestinal tract, upper airways, and genital tract. Signup and view all the answers

How many species of microorganisms approximately inhabit the gut mucosa?

More than 700 species. Signup and view all the answers

What is the thickness of the gut mucosa?

0.1 mm thick. Signup and view all the answers

What role does the gut mucosa play in relation to the external environment?

It acts as an interface between the sterile internal body and the external environment. Signup and view all the answers

Which statement is incorrect regarding the bacterial presence in humans?

Bacteria are only found in the gastrointestinal tract. Signup and view all the answers

What is a physiologic importance of gastrointestinal microflora?

They play a role in protecting against pathogens and assisting in digestion. Signup and view all the answers

What is a primary objective of studying gastrointestinal microflora?

To understand their physiologic importance and identify clinically important species. Signup and view all the answers

What is the primary purpose of fecal microbiota transplantation (FMT)?

To treat C. difficile infections Signup and view all the answers

Which bacteria is primarily responsible for the development of gastric diseases including ulcers and cancer?

Helicobacter pylori Signup and view all the answers

Which factor can alter the density of microbes in the stomach?

Acidity levels Signup and view all the answers

What property of Helicobacter pylori allows it to survive the harsh acidic environment of the stomach?

Production of urease Signup and view all the answers

Which of the following conditions has FMT been used to treat beyond C. difficile infections?

Diabetes Signup and view all the answers

What is the typical pH range of stomach acid?

1.5 - 3.5 Signup and view all the answers

Helicobacter pylori is characterized by which feature?

It has a flagellated structure Signup and view all the answers

What role does the pH of stomach acid play in relation to microbes?

It can kill most microbes Signup and view all the answers

What characterizes resident flora in a given area?

They can establish permanently on surfaces. Signup and view all the answers

Which type of flora is characterized as non-permanent inhabitants?

Transient flora Signup and view all the answers

What factor does NOT determine the types of microorganisms in the GIT?

Dietary patterns Signup and view all the answers

Which pathogen is mentioned as a common cause of infectious enteritis due to its survival in gastric juice?

Salmonella typhimurium Signup and view all the answers

How does the health status of a person affect receptor expression on epithelial cells?

Sick individuals express receptors for pathogenic organisms. Signup and view all the answers

What is a potential impact of perturbation in the physiology of the GIT?

It impacts the growth and proliferation of microbes. Signup and view all the answers

What happens to receptor expression on epithelial cells when a person is seriously ill?

Receptors for pathogenic organisms are expressed. Signup and view all the answers

Which of the following best describes transient flora?

They are present for short periods and can be pathogenic. Signup and view all the answers

Which test is classified as non-invasive for detecting pylori?

Stool antigen test Signup and view all the answers

What is the predominant organism found in the colon?

Bacteroides Signup and view all the answers

What role do Payer's patches play in the gut?

Detection of pathogens Signup and view all the answers

What characterizes the terminal ileum in terms of microbial concentration?

Has microbial concentration exceeding 10^9 /mL Signup and view all the answers

What is the ratio of anaerobic to aerobic species in the colon?

100:1 Signup and view all the answers

Which of the following is NOT a common symptom of colitis?

Constipation Signup and view all the answers

What is primarily responsible for maintaining the microbial balance in the gut lumen?

Goblet cells Signup and view all the answers

What indicates a dysfunctional ileocecal valve?

Similar microbiology to the colon Signup and view all the answers

Study Notes

Introduction to Gastrointestinal Microflora

Human beings host a diverse array of microorganisms, primarily residing in the gastrointestinal tract (GIT).
The GIT mucosa, a single layer columnar epithelium approximately 0.1 mm thick, covers an estimated area of 300 m² and supports over 700 microbial species.
The human fetus is initially sterile until exposure to external environments during birth.

Definition and Types of Microflora

Normal microbial flora refers to microorganisms inhabiting healthy individuals' skin and mucous membranes.
Resident flora are stable and can reestablish if disturbed, while transient flora are only temporarily present and may be pathogenic.

Factors Influencing Microflora

The distribution of microorganisms along the GIT is influenced by environmental, microbial, and host factors.
Physiological perturbations (e.g., varying pH levels) can affect microbial growth, as seen with Salmonella typhimurium.
Epithelial receptor expression can change based on the health status of the individual.

Physiological Importance of Gastrointestinal Microflora

Normal flora perform various essential functions, including:
- Metabolic Functions: Produce vitamins like K and B, and short-chain fatty acids.
- Infection Prevention: Compete for nutrients and space, producing toxic metabolites to inhibit pathogen colonization.
- Immune System Priming: Germ-free animals show poorly developed immune systems, emphasizing microbial benefits.

Probiotics and Prebiotics

Probiotics are live microorganisms providing health benefits, effective against dysbiosis, IBS, IBD, and antibiotic-associated diarrhea.
Prebiotics are non-digestible ingredients that stimulate beneficial bacteria, aiding gut health and used in treatments like fecal microbiota transplantation for C. difficile infections.

Clinically Important Microbes in GIT

The oral cavity contains both facultative and strict anaerobes; Streptococcus mutans is notable for its cariogenic properties.
The stomach's highly acidic environment (pH 1.5-3.5) limits microbial presence to less than 1000 organisms/mL, impacting microbial survival.

Helicobacter pylori

A significant pathogen, H. pylori is a Gram-negative bacillus linked to various gastric diseases including gastritis, ulcers, and gastric cancer.
It employs various virulence factors (e.g., urease, proteases) to establish itself in the gastric mucosa.
Detection methods for H. pylori include invasive techniques (gastric biopsy) and non-invasive tests (urea breath and stool antigen tests).

Microbial Distribution in the Small Intestine

The proximal small intestine hosts limited microbes (<10,000 organisms/mL), primarily lactobacilli and enterococci.
Peyer’s patches in the ileum detect pathogens and initiate immune responses, while goblet cells maintain mucosal integrity.

Composition of the Colon

The colon is densely populated with microorganisms (10¹¹ to 10¹² CFU/g of feces), predominantly anaerobes such as Bacteroides and Clostridium.
The ratio of anaerobic to aerobic bacteria is approximately 100:1, with adult feces consisting of bacteria, sloughed epithelium, and undigested food.

Colitis

Colitis refers to colon inflammation caused by pathogens either through direct invasion or toxin ingestion.
Symptoms include purulent and bloody diarrhea, fever, tenesmus, and abdominal pain.

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Description

Test your knowledge on the microbiome of the gastrointestinal tract with this comprehensive quiz. Explore definitions, advantages, and clinically important micro-flora, as well as preparation for surgeries. Perfect for students and professionals in the medical field.