GI Tract

Question 1

Where is the myenteric plexus located?

Answer 1

Between the circular and longitudinal smooth muscle layers of the muscularis. It controls GI tract motility, particularly the frequency and strength of contraction of the muscularis. Part of the enteric nervous system.

Question 2

What is the submucosal plexus?

Answer 2

Plexus found in the submucosa and it is responsible for sensing the environment within the lumen, regulating GI blood flow and controlling epithelial cell function. Part of the enteric nervous system.

Question 3

What does salivary amylase do?

Answer 3

It breaks down carbohydrates in the mouth by breaking alpha 1,4 glycosidic bonds between individual glucose monomers. It works at an optimum pH of 6.9 (range 4-11). Produced by acini cells.

Question 4

What is the oesophagus?

Answer 4

A muscular tube that connects the pharynx to the stomach. It is made of stratified squamous epithelium. It is posterior to the trachea.

Question 5

In which segment of the abdomen is the stomach located?

Answer 5

In the left hypochondrium and partly in the epigastric region.

Question 6

What do parietal cells do?

Answer 6

They are located in the stomach and they secrete hydrochloric acid which denature proteins and activated pepsinogen (converting it to pepsin which breaks downs specific peptide bonds). Also produces intrinsic factor, which is essential for the absorption of vitamin B12.

Question 7

What do chief cells do?

Answer 7

Secrete pepsinogen and gastric lipase.

Question 8

What do G cells do?

Answer 8

Secrete the hormone gastrin.

Question 9

What do alpha cells in the pancreas secrete?

Answer 9

Glucagon.

Question 10

What do beta cells in the pancreas secrete?

Answer 10

Insulin.

Question 11

What do delta cells in the pancreas secrete?

Answer 11

Somatostatin.

Question 12

What are the 4 lobes of the liver?

Answer 12

Right, left, caudate and quadrate.

Question 13

Where are paneth cells found and what do they do?

Answer 13

In the small intestine. They secrete lysozyme and are capable of phagocytosis.

Question 14

What is the blood supply of the GI tract?

Answer 14

The abdominal aorta branches into 3 trunks:

• coeliac trunk.
• superior mesenteric artery.
• inferior mesenteric artery.

Question 15

What is the main function of the duodenum?

Answer 15

Mixing secretions from pancreas, liver and its own with the food, neutralization of acid, further digestion and absorption.

Question 16

What is the main function of the jejunum?

Answer 16

Completing breakdown, nutrient reabsorption.

Question 17

What is the function of the ileum?

Answer 17

Nutrient absorption.

Question 18

What is passive absorption?

Answer 18

Diffusion. Slow, requires a concentration or charge gradient.

Question 19

What is facilitated absorption?

Answer 19

Slightly faster, involves membrane carrier, controllable.

Question 20

What is emulsification?

Answer 20

(In digestion) the breakdown of fat globules in the duodenum into tiny droplets, which provides a larger surface area on which the enzyme pancreatic lipase can act to digest the fats into fatty acids and glycerol.

Question 21

What are emulsifying agents?

Answer 21

Substances that are soluble in both fat and water. Emulsifying agents include: fatty acids, monoglycerides, cholesterol, lecithin, protein and bile acids.

Question 22

What happens to carbohydrate and protein not digested in the small intestine?

Answer 22

It is fermented by the colonic microflora to short chain fatty acids and gases. Acetic, propionic and butyric acid. All have some health benefits and act as an energy source.

Question 23

Name 4 common eating disorders.

Answer 23

Anorexia nervosa, bulimia nervosa, binge eating disorder, atypical eating disorder.

Question 24

What are the Russell’s sign?

Answer 24

Calluses on the knuckles/back of hand due to repeated self-induced vomiting over a long period of time.

Question 25

What is binge eating?

Answer 25

3/5 of the following:

• Eating much more quickly than usual.
• Eating until uncomfortably full.
• Eating a lot when not hungry.
• Eating alone because of embarrassment.
• Feeling very bad or guilty after eating.

Question 26

What is refeeding syndrome?

Answer 26

Refeeding syndrome can be defined as the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial refeeding (whether enterally or parenterally). These shifts result from hormonal and metabolic changes and may cause serious clinical complications.