Harley, John P. Department of Biological Sciences, Eastern Kentucky University, Richmond, Kentucky.
Last reviewed:January 2019
Show previous versions
- Nose and nasopharynx
- Respiratory tract
- External ear
- Small intestine
- Large intestine (colon)
- Genitourinary tract
- Related Primary Literature
- Additional Reading
Microbial flora harbored by normal, healthy persons. The term "human microbiota" pertains to the totality of microorganisms that are present on and in the human body. Although a normal fetus is sterile, the infant is exposed to an increasing number of microorganisms during and after birth. Subsequently, those microorganisms best adapted to survive and colonize particular sites establish themselves and become predominant. Moreover, in a healthy human, internal tissues (such as the brain, blood, cerebrospinal fluid, and muscles) are normally free of microorganisms. Conversely, surface tissues (such as skin and mucous membranes) are constantly in contact with environmental microorganisms and are readily colonized by certain microbial species (Fig. 1). In general, the mixture of microorganisms regularly found at any anatomical site is referred to as the normal microbiota, the indigenous microbial population, the microbiome, the microflora, or the normal flora. For consistency, the term normal microbiota is used here. Because bacteria make up most of the normal microbiota, they are emphasized over the fungi (mainly yeasts) and protozoa. See also: Bacteria; Ecological communities; Fungi; Immune regulation by the microbiome; Medical bacteriology; Microbial ecology; Microbial interactions; Microbiome; Protozoa
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 9000 highly qualified scientists and 43 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information