Gastro Physiology

Question 1

Gastro Enzymes

Answer 1

Amylase = present in saliva and pancreatic secretions > breaks down starch into sugar

Brush Border Enzymes: = involved in Carb breakdown

Maltase = Disaccharide maltose to glucose + glucose

Sucrase = Sucrose to fructose + glucose

Lactase = Disaccharide lactose to glucose + galactose

Question 2

Somatostatin (Hormone involved in Food Digestion)

Answer 2

Source = D cells in pancreas and stomach

Stimulus = Fat, bile salts and glucose in intestinal lumen

Action:
(Decreases/Inhibits everything)
- Decreases acid and pepsin secretion
- Decreases Gastrin secretion
- Decreases pancreatic enzyme secretion
- Decreases Insulin and glucagon secretion
- Inhibits trophic effects of Gastrin
STIMULATES gastric mucous production

Question 3

VIP (Hormone involved in Food Digestion)

Answer 3

Source = Small intestine, Pancreas

Stimulus = Neutral

Action:

• Stimulates secretion by pancreas and intestines
• Inhibits ACID secretion

NB VIPoma !

• 90% arise from pancreas
• large volume diarrhoea
• weight loss
• dehydration
• Hypokalaemia
• Hypochlorhydia

Question 4

Secretin (Hormone involved in Food Digestion)

Answer 4

Source = S cells in upper Small Intestine

Stimulus = Acidic chyme, Fatty acids

Action:

• Increases secretion of bicarbonate rich fluid from pancreas and hepatic duct cells
• Decreases gastric acid secretion
• Trophic effect on pancreatic acinar cells

Question 5

CCK (Hormone involved in Food Digestion)

Answer 5

Source = I cells in upper Small Intestine

Stimulus = Partially digested proteins and triglycerides

Actions:

• Increases secretion of enzyme rich fluid from pancreas
• Contraction of gallbladder and relaxation of sphincter of Oddi
• Decreases gastric emptying
• Trophic effect on pancreatic acinar cells
• Induces SATIETY

Question 6

Gastrin (Hormone in Food Digestion)

Answer 6

Source = G cells in antrum of stomach

Stimulus:

• Distension of stomach
• Vagus nerve (mediated by gastrin-releasing peptide)
• Luminal peptides/amino acids

Inhibited by:

• Low Antral pH
• Somatostatin

Actions:

• Increases HCL
• Increases Pepsinogen and IF secretion
• Increases Gastric motility
• Stimulates parietal cell maturation

Question 7

Liver Disease and Immunoglobulins

Answer 7

Alcoholic liver disease - assoc w raised IgA

PBC - Assoc w Raised IgM

Autoimmune hepatitis - Assoc w Raised IgG