Human flora

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Human flora refers to the collection of microorganisms, including bacteria, fungi, and archaea, that reside on and within the human body. These microorganisms are found in various parts of the body, such as the skin, gut, mouth, and respiratory tract, and play crucial roles in maintaining health and preventing disease.

Overview

The human body is host to a vast number of microorganisms, collectively known as the microbiota. The term "flora" is a historical reference to the plant-like appearance of bacterial colonies, although it is now understood that these are not plants. The human microbiota is composed of trillions of cells, outnumbering human cells by a factor of 10 to 1. The majority of these microorganisms are found in the gastrointestinal tract, particularly in the colon.

Composition

The composition of human flora varies significantly between individuals and is influenced by factors such as diet, age, genetics, and environment. The major groups of microorganisms found in human flora include:

• Bacteria: The most abundant and diverse group, with key genera including Bacteroides, Firmicutes, Actinobacteria, and Proteobacteria.
• Fungi: Less abundant than bacteria, with Candida being a common genus found in the human body.
• Archaea: Present in smaller numbers, often found in the gut, with Methanobrevibacter smithii being a notable species.

Functions

Human flora performs several essential functions, including:

• Digestion: Assisting in the breakdown of complex carbohydrates and the synthesis of vitamins such as Vitamin K and Vitamin B12.
• Immune System Modulation: Training the immune system to recognize and respond to pathogens while tolerating commensal organisms.
• Protection: Competing with pathogenic microorganisms for resources and space, thereby preventing infections.

Dysbiosis

An imbalance in the human flora, known as dysbiosis, can lead to various health issues, including inflammatory bowel disease, obesity, and allergies. Dysbiosis can be caused by factors such as antibiotic use, poor diet, and stress.

Research and Applications

The study of human flora is a rapidly growing field, with research focusing on understanding the complex interactions between microorganisms and their human hosts. This research has led to the development of probiotics and prebiotics as therapeutic interventions to restore and maintain healthy microbiota.

Also see

• Microbiome
• Gut flora
• Probiotics
• Prebiotics
• Symbiosis