GI/Liver 2: GI

Question 1

What effect does too much thyroxine have on metabolic rate?

Answer 1

Increases metabolic rate.

Question 2

What is ghrelin and what is its function?

Answer 2

A peptide hormone released mainly by the stomach when empty to stimulate appetite.

Question 3

What is leptin and what is its function?

Answer 3

A peptide hormone released by white adipose tissue. Leptin regulates the hunger response by suppressing the hunger response when your body doesn’t need energy.

Question 4

What happens to leptin in obesity?

Answer 4

In obesity, more white adipose tissue, therefore produce more leptin, but develop leptin resistance so no longer can suppress hunger response.

Question 5

Name the 8 hormones that regulate fuel metabolism.

Answer 5

“CAT SINGG”
Cortisol
Adrenaline
Thyroxine
Somatostatin
Insulin
Noradrenaline
Growth Hormone (somatotropin)
Glucagon

Question 6

Which part of the developing gut has both dorsal and ventral mesenteries?

Answer 6

The foregut.

Question 7

How does the pancreas develop embryologically?

Answer 7

In two separate buds (dorsal and ventral) off the duodenum, which then eventually fuse together.

Question 8

What happens to the orientation of the stomach during embryological development?

Answer 8

It rotates 90 degrees.

Question 9

Why do the intestines herniate and rotate into the umbilical cord during embryological development?

Answer 9

Developing length of intestine too long to fit into abdominal cavity, returns into abdominal cavity after coiling of the small intestine.

Question 10

Why does the most distal anal canal have different epithelium to the proximal anal canal (hint: embryology!)?

Answer 10

Different embryological origins.
Distal anal canal; ectoderm on outside of cloaca.
Proximal anal canal; endoderm on inside of cloaca.
Cloaca divided by urorectal septum, then ectoderm of cloaca invaginates into anal pit and cloacal membrane breaks down.

Question 11

What does the growth of the liver divide the ventral mesentery into during embryological development?

Answer 11

Lesser omentum and falciform ligament.

Question 12

Where is the lesser sac?

Answer 12

Posterior to the stomach.

Question 13

What are the 3 key functions of the colon?

Answer 13

1. absorption of water and electrolytes.
2. excretion of waste
3. production of vitamins/regulation of immune system, microbiome.

Question 14

What is a redundant colon?

Answer 14

Anatomical variation, longer part of colon e.g. redundant transverse colon. Can sometimes cause issues such as constipation or volvulus.

Question 15

Which histological section of the colon contains the interstitial cells of Cajal?

Answer 15

In the muscularis propria, in the inner circular muscle.

Question 16

Is the internal anal sphincter under voluntary or involuntary control?

Answer 16

Involuntary.

Question 17

What causes the anorectal angle, helping to preserve continence?

Answer 17

The puborectalis muscle sling.

Question 18

What happens in the nervous system when stool enters the rectum?

Answer 18

Stretch receptors relay information to the CNS, which sends motor signals to rectum and internal anal sphincter, which releases a small amount of stool into the anal canal.

Question 19

What motor nerve keeps the external anal sphincter contracted until it is appropriate to defecate?

Answer 19

The pudendal nerve.

Question 20

What are the 4 phases of defecation?

Answer 20

1. Basal
2. Pre-expulsive
3. Expulsive
4. Termination

Question 21

What percentage of cardiac output is hepatic blood supply?

Answer 21

25%

Question 22

Bilirubin is the by-product of haemoglobin breakdown.
Which compound is returned to the liver by the enterohepatic circulation?

Answer 22

Urobilinogen

Question 23

What is the enterohepatic urobilinogen cycle (4 steps)?

Answer 23

1. Conjugated bilirubin is secreted into the duodenum in bile.
2. In the intestine, converted into urobilinogen.
3. Some urobilinogen is reabsorbed from the intestine, entering the portal system.
4. A portion of this urobilinogen is then filtered by the liver into bile and is again secreted into the duodenum.

Question 24

In hepatocytes, microsomal enzyme uridine diphosphoglucoronosyl transferase (glucuronyl transferase) catalyses the formation of what metabolite?

Answer 24

Conjugated bilirubin.

Question 25

Which cells found in the liver are part of the reticuloendothelial system?

Answer 25

Kupffer cells

Question 26

Which cells of the pancreas secrete somatostatin?

Answer 26

Delta (D) islet cells.

Question 27

Which cells of the pancreas secrete insulin?

Answer 27

Beta (B) islet cells.

Question 28

Which cells of the pancreas secrete glucagon?

Answer 28

Alpha (A) islet cells.

Question 29

Which cells of the pancreas secrete pancreatic polypeptide?

Answer 29

F islet cells.

Question 30

What clusters of cells in the pancreas secrete insulin, glucagon, somatostatin, and pancreatic polypeptide?

Answer 30

The Islets of Langerhans.

Question 31

Obstructive jaundice is commonly caused by gall stones within what structure?

Answer 31

Common bile duct.

Question 32

In what form is bilirubin mostly excreted in faeces? What process produces this compound from urobilinogen?

Answer 32

Stercobilinogen.
Bacterial enzyme hydrolysis.

Question 33

Roughly how much bile can the gallbladder store?

Answer 33

Up to 50ml

Question 34

The presence of what substances in the small intestine trigger the release of cholecystokinin from I-cells in the mucosal lining?

Answer 34

Amino acids, lipids, free fatty acids, peptides.