4. Bariatric surgery, ghrelin, exam questions

Question 1

What is gastric banding? Reversible?

Answer 1

One of less invasive techniques: gastric banding (put band on upper part of stomach, or balloon in the stomach): decrease energy intake. Fully functional stomach. Just less space. Reversible.

Question 2

What is the roux-en Y gastric bypass?

Answer 2

1. Stomach is cut, into a very small functioning unit.
2. End of small intestine: cut.
   > One part is attached to the functional stomach unit
   > Other end is sewn to a loop that has been pulled up to meet it. (remaining part that is still attached to the non-functioning stomach, where the enzymatic juices come from)
   p.30

Question 3

What is the mechanism of the Roux-en-Y gastric bypass? Is it reversible? For what group of people is it used?

Answer 3

> Mechanism: restriction of absorption. Enzymatic juices only reach the food very late in the small intestine and the functioning unit of the stomach is very small.
Ghrelin levels go down. Non-reversible, only in very very obese patients: losing weight is needed to survive.

Question 4

What is sleeve gastrectomy? Reversible? Mechanism?

Answer 4

Resection of more than 80% of the stomach. Max 100 mL in stomach.
Non-reversible
Restriction and less hormone secretion

Question 5

What is bilopancreatic diversion (BPD) with duodenal switch (DS)? How invasive?

Answer 5

Sleeve gastrectomy + cut at duodenum.

Duodenum communicates with the rest of the functional intestine that is left, only at the end of the small intestine.
Degree of malabsorption is much more, as enzymes will only reach the food at the end of intestine and stomach is decreased in volume.

Most invasive.

Question 6

Mechanism of effect BPD + DS?

Answer 6

 Mechanism of effect: combination of restriction with a considerable degree of malabsorption

Question 7

What is endobarrier therapy? (not surgery, still completely functional)

Answer 7

1. Endoscope to check area before placement
2. Balloon is placed into the first part of small intestine.

• Reduced body weight and blood sugar at same time
• Go home and work after brief recovery: reversible

Question 8

Mechanism endobarrier therapy?

Answer 8

 Mechanism: restriction of absorption

Question 9

What is duodenal mucosal resurfacing?

Answer 9

A tube is inserted into the duodenum. Hot water is led through the tube: burns away the mucosal layer of the small intestines and it is being renewed

Question 10

What is the result of duodenal mucosal resurfacing?

Answer 10

improved signalling to pancreas

Question 11

What is ghrelin involved in besides stimulating appetite?

Answer 11

in growth hormone signalling.

Question 12

How is ghrelin regulated?

Answer 12

• Before a meal, ghrelin goes up. If stomach if full, ghrelin goes down
  Higher BMI = lower ghrelin
  Leptin (upreg)
  Somatostatin (downreg)
  To name a few

Humans have a lot of inter-individual variation

Question 13

Some effects of ghrelin?

Answer 13

growth hormone release
heart rate up
appetite up
thermoregulation down

Question 14

Where is ghrelin secreted?

Answer 14

Ghrelin is secreted in the stomach.

• Ghrelin cells lie in between parietal, chief and somatostatin cells.

Question 15

Injecting ghrelin in rats: What happens with injection in abdomen vs brain?

Answer 15

Abdomen: no reduction in food intake
Brain: also no reduction, but food intake will go sky high + long-lasting effect

Question 16

Digestion of carbohydrates -> absorbable sugars is associated with trans …. and …

Answer 16

translocation and transformation

Question 17

The vagus affects gastro-intestinal responses during the cephalic phase with what type of responses?

Answer 17

with motor and secretory behaviour of the gastrointestinal tract

Question 18

 After the oral phase (so, gastric phase), motor and secretory behavior can be maintained by what in the stomach?

Answer 18

the presence of oligopeptides in the stomach (protein digestion products). Presence of H+ and pepsin do not have any effect on the motor behaviour. Oligopeptides trigger cells to secrete gastrin.

Question 19

 During meal, the amount of energy released from the stomach to the duodenum in kj/min is larger/equal to/smaller than the normal energy expenditure of the body

Answer 19

larger

Question 20

To what is the secretion of regulatory peptide PYY by the colon a response?

Answer 20

This secretion is a response to the passage of undigested/unabsorbed fatty acis. ‘slow down’.

Question 21

Which of the following is NOT a potential product of the digestion of amylopectin by amylase?

Glucose
Iso-maltose
Maltose
Fructose

Answer 21

Fructose

Question 22

What monomer is not absorbed by co-transport of Na+?

Lactose
Glucose
Fructose
Galactose

Answer 22

Fructose.

Lactose is a dimer (glucose - galactose)
The rest needs Na+

Question 23

Micelles have a larger/smaller diameter than chylomicrons

Answer 23

Smaller.
Micelles = 3-50 nm
Chylomicrons = 100 - 350 nm

Question 24

 The time of arrival of the food components at the ileo-caecal valve (between small and large intestine) after oral ingestion is mainly determined by ..

Answer 24

The rate of gastric emptying

Question 25

What borders the small intestine?

Answer 25

Pylorus and ileo-caecal valve

Question 26

Hydrolysis of peptide bonds: a function of HCL?

Answer 26

No.
HCL is important in killing bacteria, conversing pepsinogen to pepsin.

Question 27

Nutritional paradox example?

Answer 27

Obesity.
Our traditional food production system attempted to solve the problem of hunger with calories, not nutrients

Question 28

Microvilli contain..

a. digestive enzymes
b. absorptive cells
c. lacteal
d. blood vessels
e. all of the above

Answer 28

a.digestive enzymes

Are extension of the plasma membrane, they can only contain digestive enzymes.

Question 29

What type of tissue is clearly different for the fundus and the antrum of the stomach?

Answer 29

Thickness of the muscularis

Question 30

Where is amylase present?

Answer 30

• saliva
• juice of exocrine pancreas