Lecture 67 - Microbiome

Question 1

Sterile body tissues (those that will only have microorganisms present bc of disease) are _____, _____, and deep tissues. Keep in mind the bladder, uterus, esophagus and bronchi/alveoli are nearly sterile.

Answer 1

Blood, CSF, and deep tissues

Question 2

_____S rRNA is the key gene used for determining microbiome composition.

Answer 2

16S rRNA

Question 3

____ diversity describes the species richness of a microbiome (basically the number of species/OTU count), while _____ diversity describes how different the microbiome composition is in one environment than another (e.g. gut vs vagina).

Answer 3

Alpha

Beta

Question 4

As you move from the stomach to the small intestine, and then into the colon, what is the trend in terms of number of microbes present? Keep in mind the colon has very low O2, so it is dominated by anaerobes.

Answer 4

There is a large increase (about a billion fold) moving from the stomach to the colon.

Question 5

_______ and _______ comprise about 90% of the GI microbiome.

Answer 5

Bacteroides and Firmicutes

Question 6

Two of the most important functions of the microbiome include ______ system modulation and conversion of insoluble fiber into ___ ___ ___ ___, including acetate, propionate, and butyrate (this last one is a major energy source for enterocytes). Keep in mind these can have systemic effects, as evidenced by the presence of _____ on cells of many different tissues.

Answer 6

Immune system modulation

Short Chain Fatty Acids

Receptors

Question 7

The intestinal epithelium is a ____-cell layer comprised about 80% of enterocytes and 20% of specialized cells. A healthy intestinal epithelium is important for maintaining a healthy microbiome.

Answer 7

Single-cell layer

Question 8

The key to a healthy microbiome is ______. That is, a decrease in this is indicative of unhealthy or disease states.

Answer 8

Richness (diversity)

Question 9

Dendritic cells in the GI induce a tolerogenic response to common commensals by activating T__ to secrete IL-10. B. _______ that produces PSA is one of these common commensals, and the PSA helps to induce tolerance through the aforementioned mech.

Answer 9

Tregs

B. fragilis

Question 10

The GI microbiome is a major synthesizer of Vit___.

Answer 10

Vit B