Lecture 8

Question 1

The assemblage of microbes living in a habitat is referred to as:

Answer 1

microbiota / gut Microbiota

Question 2

1-3% of body mass in and on the average adult human body is comprised of

Answer 2

microbes

Question 3

Bacteria vastly outnumbers the other kinds of microorganisms; the ratio of bacterial cells to human cells is estimated to be around:

Answer 3

1.3 : 1

we have more bacterial cells than the cells that make up the structure of our body

Question 4

what is the function of the colon

Answer 4

The colon is the site of breakdown of materials that escape digestion (dietary fibre, resistant starches, and non-carbohydrate substrates)

Question 5

Colonic bacteria produce enzymes that ferment what?

Answer 5

colonic bacteria can produce enzymes that ferment soluble fibers

Question 6

Colonic bacteria play a crucial role in the fermentation of soluble fibers, leading to the production of…

Answer 6

short-chain fatty acids (SCFAs)

colonic bacteria → soluble fibers → SCFAs

Question 7

what are the three SCFAs

Answer 7

Acetate (2 carbons)

Propionate (3 carbons)

Butyrate (4 carbons)

Question 8

95% of SCFAs are used by what?

Answer 8

colonic cells as a source of energy

and provide about 10% of the total daily calories for the host

Question 9

Describe the function of Colonic cells

Answer 9

maintaining the structural integrity of the large intestine

serving as a protective barrier

Question 10

role of SCFAs

Answer 10

1. SCFAs serve as messengers between the microbiota and the immune system
2. development and function of intestinal epithelial cells and leukocytes (immune cells)

Question 11

Bacteria in the colon also produces which two vitamins

Answer 11

B vitamins (thiamine, riboflavin, niacin, biotin,
pantothenic acid, and folate)

vitamin K

Question 12

Vitamins originating from the diet are absorbed where?

Answer 12

Vitamins originating from the diet are absorbed in the small intestine

Question 13

microbe-produced vitamins are absorbed where

Answer 13

microbe-produced vitamins are absorbed in the colon

Question 14

define Dietary fibre:

Answer 14

Dietary fiber refers to non-digestible carbohydrates and lignin that are intrinsic and intact in plant foods.

Question 15

define Functional fibre:

Answer 15

Functional fibre: isolated, non-digestible carbohydrates, extracted, or manufactured that have beneficial effects to humans

Question 16

What does the sum of dietary and functional fibres encompass

Answer 16

the total amount of fibre consumed by an individual

Question 17

define Soluble fibre (soluble in water):

Answer 17

type of dietary fiber that dissolves or swells in water

Question 18

examples of Soluble fibre (soluble in water)

Answer 18

➢ Pectin
➢ Gums
➢ Mucilages

Question 19

what foods contain Soluble fibre (soluble in water)

Answer 19

Found in fruits, legumes, oats, and some vegetables

Question 20

how are Soluble fibers fermented? What do bacteria gain from fermenting Soluble fibers?

Answer 20

Fermented by health-promoting bacteria residing in the colon

through fermentation of fibres, bacteria can obtain energy and other substances (like nitrogen) that promote their growth

Question 21

what are the byproducts of this fermentation of soluble fibers

Answer 21

Fermentation produces SCFAs (acetic, butyric, and propionic acids), that can be used by the human host;

this occurs mostly in the cecum and the ascending portion of the colon

Question 22

define Insoluble fibre:

Answer 22

type of dietary fiber that does not dissolve in water

Question 23

Types of Insoluble Fiber:

Answer 23

➢ Cellulose
➢ Hemicellulose
➢ Lignin

Question 24

are Insoluble fiber Non-Fermentable?

Answer 24

Yes

poorly or non-fermentable by gut bacteria

Question 25

how does Insoluble fiber promotes colonic health

Answer 25

increasing fecal volume
exerting a detoxifying effect
increase peristaltic rate

Question 26

how does insoluble fiber contribute to Detoxifying Effect

Answer 26

Insoluble fiber has a detoxifying effect in the colon.

It can absorb or attach to hydrophobic carcinogens, preventing them from interacting with the colonic mucosa

This process facilitates the excretion of these carcinogens in the feces

Question 27

peristaltic rate:

Answer 27

the speed or frequency at which ingested food moves through the digestive system