GI Physiology

Question 1

What is Ludwig’s angina?

Answer 1

A serious, potentially life-threatening cellulitis, of the floor of the mouth, usually occurring in adults with concomitant dental infections and if left untreated, may obstruct the airways, necessitating tracheostomy.

Question 2

What are the 3 salivary glands?

Answer 2

1) Submandibular. 2)Sublingual. 3)Parotid.

Question 3

What does mastication do?

Answer 3

1) Reduces particle size within the food bolus.
2) Mixes food with salvia (lubrication and enzymes).
3) Increases surface area.

Question 4

What is achalasia?

Answer 4

The lower esophageal sphincter (LES) is a muscular ring that closes off the esophagus from the stomach. If you have achalasia, your LES fails to open up during swallowing, which it’s supposed to do. This leads to a backup of food within your esophagus.

Question 5

What are oesophageal varices?

Answer 5

Oesophageal varices are extremely dilated sub-mucosal veins in the lower third of the esophagus. They are most often a consequence of portal hypertension, commonly due to cirrhosis; patients with esophageal varices have a strong tendency to develop bleeding.

Question 6

What is a Sengstaken tube and what is it used for?

Answer 6

It is a 3 lumen tube (1- inflate gastric balloon, 2-inflate oesophageal balloon, 3-aspirate gastric contents) that is used to buy time in life-threatening upper GI bleeds caused by ruptured oesophageal varices. Used when other treatments haven’t worked.

Question 7

What is Cimetidine?

Answer 7

A histamine H2 receptor antagonist that inhibits stomach acid production.

Question 8

What are the 3 phases of gastric secretion?

Answer 8

1) Cephalic 2) Gastric 3)Intestinal

Question 9

What foods directly stimulate gastrin release?

Answer 9

• Protein/peptides
• Coffee
• Calcium rich
• Alcohol oddly doesn’t appear to

Question 10

Where is enteropeptidase found and what does it do?

Answer 10

It is found in the small intestine and it activates trypsinogen.

Question 11

What are Kupffer cells?

Answer 11

Specialised macrophages located in the liver.

Question 12

What is enteral feeding?

Answer 12

Nutritionally complete feeding directly into stomach, duodenum or jejunum.

Question 13

What is parenteral feeding?

Answer 13

IV feeding, bypassing normal process of eating and digestion.

Question 14

What is Loperamide?

Answer 14

A gut selective opiate Mu receptor agonist. It decreases tone and activity of myenteric plexus and slows colonic transit leading to increased water absorption.

Question 15

What is Prucalopride?

Answer 15

Gut selective 5HT4 receptor agonist, increase colonic (and other gut) motility. Licensed or use of chronic constipation in UK.

Question 16

What is ferritin?

Answer 16

A soluble cellular iron store. Iron safe and it is readily available from the reticuloendothelial system.

Question 17

What is haemosiderin?

Answer 17

Insoluble conglomerates of ferritin as a cellular iron store. Iron only slowly available.

Question 18

What is hepcidin?

Answer 18

Central regulatory hormone of systemic iron homeostasis, Hepcidin deficiency is the cause of iron overload in hereditary haemochromatosis, iron-loading anaemias and hepatitis C. Hepcidin works by binding to ferroportin and degrading it.

Question 19

What is non-haem iron absorbed?

Answer 19

Non-haem iron must be reduced from the ferric to the ferrous form by duodenal cytochrome b1 (dCytb1). This process is influences by vitamin C.

Question 20

What is DMT1?

Answer 20

Divalent metal transporter 1. An electrogenic pump that allows iron (Fe2+) to be taken into the enterocyte. Its expression is unregulated in iron deficiency. Iron is exported from the enterocyte to the circulating plasma through ferroportin and hepcidin.

Question 21

What is Ferroportin?

Answer 21

A transmembrane protein that allows iron to move from enterocyte to circulating plasma. Also essential for the release of iron from macrophages. Interaction between ferroportin and hepcidin is the single most important regulator of GI iron absorption (and RES iron release).

Question 22

What is transferrin?

Answer 22

A glycoprotein, synthesised in the liver, involved in plasma iron transport. Synthesised in hepatocytes. 2 iron binding domains. 30% saturated with Fe.

Question 23

What is hereditary haemochromatosis?

Answer 23

An autosomal recessive disorder of iron metabolism causing iron overload. Abnormalities in the HFE gene are responsible for the vast majority of cases. Though to principally reduce hepicidin production. Homozygous mutation of C282Y mutation of the HFE gene is most common.

Question 24

What is the percentage saturation of transferrin in normal, iron deficiency anaemia and hereditary haemochromatosis cases?

Answer 24

1) Normal 30%
2) IDA 15%
3) HHC 100%

Question 25

What is restrictive cardiomyopathy?

Answer 25

The walls of the ventricles become stuff, but not necessarily thickened.

Question 26

What is sideroblastic anaemia?

Answer 26

When erthrocytes take in iron but don’t transfer it into haem.