Fnm 023 Physiology Of The Gi Tract: Intestinal Absorption

Front 1

However, Fe^2+ and Ca^2+ are absorbed in the intestine regardless of how much is already in the system T/F

Back 1

F - Fe^2+ and Ca^2+ are regulated according to bodily needs

Front 2

What is transcellular absorption?

Back 2

Absorption across cells

Front 3

What is paracellular absorption?

Back 3

Absorption between cells

Front 4

Which enzyme initiates protein digestion, and where?

Back 4

Pepsin in the stomach

Front 5

Where does protein digestion terminate?

Back 5

In the small intestine (through pancreatic enzyme) in the luminal phase

Front 6

What is the 'brush border'?

Back 6

Name for the microvilli-covered surface of *simple cuboidal epithelium* and *simple columnar epithelium* cells found in certain locations of the body.

Contain enzymes e.g. peptidases

Front 7

Transport of di and tripeptides into intestinal cells is proton-dependent T/F

Back 7

T

Front 8

Amino-acids are absorbed across the brush border via K+-dependent transporters T/F

Back 8

F, Na+ dependent transporters

Front 9

How do amino acids move from the villus cell to the blood?

Back 9

Via facilitated diffusion

Front 10

Which carbohydrates are absorbed into the jejunum via the brush border?

Back 10

Dietary lactose

Sucrose

Polysaccharides

Front 11

Dietary lactose is absorbed in the jejunum T/F

Back 11

T

Front 12

Sucrose is absorbed in the jejunum T/F

Back 12

T

Front 13

Polysaccharides are absorbed in the jejunum T/F

Back 13

T

Front 14

Which brush border transporters exist in the jejunum?

Back 14

SGLT1 (Na+-dependent (think S for Sodium))

GLUT2 (facilitated diffusion)

Front 15

Which transporter in the jejunum transports (by facilitated diffusion) glucose (as well as galactose and fructose) to the blood?

Back 15

GLUT2

Front 16

Fructose (from sucrose) is transported by GLUT5 and GLUT2 at the brush border, and GLUT2 at the ___________ membrane

Back 16

Basolateral

Front 17

Water in the body that is secreted by exocrine glands (salivary, gastric, pancreatic) is recycled T/F

Back 17

T - absorbed by paracellular (via inappropriately named 'tight' junctions) and transcellular routes

Front 18

How much water enters the GI tract from exocrine glands per day?

Back 18

~ 6 L/day (+ ~1-2 L/day from ingested water)

Front 19

How much iron is absorbed per day? How much is the average intake?

Back 19

1-2 mg absorbed/day on average

15-20 mg is the average intake

Front 20

What is the main site of absorption for iron?

Back 20

The duodenum

Front 21

Iron uptake is not affected by bodily requirements, so individuals must consume more iron when in need of it T/F

Back 21

F - The mechanism for uptake (in the DUODENUM) is *more efficient* during body iron deficiency OR increased erythropoietic activity (e.g. hypoxia or haemorrhage)

Front 22

How can iron be prevented from transfer into the blood?

Back 22

Binding to cellular apoferritin

Front 23

What is ferritin?

Back 23

Ferritin is a ubiquitous intracellular protein that stores iron and releases it in a controlled fashion.

Ferritin that is not bound to iron is known as apoferritin

Front 24

What is the function of 'hepcidin' wrt iron?

Back 24

It suppresses intestinal iron uptake (it is a liver derived peptide, hence name, I think)

Front 25

How many mg of calcium is absorbed per day? How much is taken in, on average?

Back 25

350 mg absorbed/day (dependent on body's requirement)

~1000mg ingested

Front 26

There is active uptake of calcium in the ileum T/F

Back 26

F - Passive uptake in ilem, active in the active uptake in the upper small intestine

Front 27

There is active uptake of calcium in the lower small intestine T/F

Back 27

F - upper small intestine

Front 28

If there is calcium deficiency in the blood, what is secreted to increase uptake?

Back 28

Calcitriol (1,25 dihydroxycholecalciferol)

Front 29

Phosphate absorption is not a Na+-dependent process T/F

Back 29

F, it is a Na+ dependent process

Front 30

Where is 80-90% of dietary phosphate absorbed?

Back 30

Upper small intestine

Front 31

Bile salts are recycled between the liver and GI tract. What is the name for this type of circulation?

Back 31

Enterohepatic circulation

Front 32

What are the two main bile salts?

Back 32

Cholate and chenodeoxycholate

Front 33

What is the difference between a bile acid and a bile salt?

Back 33

Bile acids are steroid acids found predominantly in the bile of mammals.

Bile salts are bile acids compounded with a cation, usually sodium

Front 34

Primary bile acids have a neutral pK T/F

Back 34

T (And so tend to be present in an undissociated form at the pH found in the biliary tact and uper small intestine)

Front 35

What is the name for the very base of the gap between two microvilli?

Back 35

A 'crypt' (above the crypt is the lumen)

Front 36

What is an intestinal gland/crypt of Lieberkühn?

Back 36

A gland found in the epithelial lining of the small intestine and colon.
The crypts secrete various enzymes, including sucrase and maltase, along with endopeptidases and exopeptidases

Front 37

Mucosal glands are found throughout the small intestine T/F

Back 37

T (they produce an isotonic fluid containing mainly NaCl)

Front 38

Electrolyte and water absorption is a function of the colon T/F

Back 38

T

Front 39

Formation and storage of faeces is a function of the small intestine T/F

Back 39

F! Function of the COLON

Front 40

Microbial fermentation is a function of the colon T/F

Back 40

T

Front 41

Which electrolytes does the colon absorb?

Back 41

Na+ and Cl- (as well as water)

Front 42

How many bacteria are in the human colon?

Back 42

10^15!

Front 43

There is a symbiotic relationship between colonic microbes and colonic epithelial function T/F

Back 43

T - the microbes can help break down various carbs etc. that enter the body


2020010311

Front 44

Specific dietary carbs selectively stimulate the growth of individual groups or species of bacteria T/F

Back 44

T

Front 45

This carb stimulates growth of bifidobacteria, which is a major contributor to colonisation resistance, thereby protecting the host form invasion by pathogenic species

Back 45

Fructo-oligosaccharides

Front 46

A live microbial food supplement which benefits the host by improving gut microbial balance.

Back 46

A probiotic

Front 47

What is a probiotic?

Back 47

A live microbial food supplement which benefits the host by improving gut microbial balance.

Front 48

A digestion-resistant oligosaccharide

Back 48

Prebiotic

Front 49

What is a prebiotic?

Back 49

A digestion-resistant oligosaccharide