Week 2 - Peptic Ulceration

Question 1

What are the 4 types of salivary glands?

Answer 1

Parotid - in cheek - serous, watery secretion

Submandibular - under chin - mainly serous secretion

Sublingual - under tongue - mainly mucous secretion

Simple - random places - mainly mucous

Question 2

What is the role of acinar cells?

Answer 2

Responsible for primary secretion, isotonic with plasma

Some salivary proteins secreted

Question 3

What is the role of duct cells?

Answer 3

Modify secretion by acinar cells

Actively reabsorb Na+ and Cl- ions

Secrete K+ and HCO3- ions

Impermeable to water

Excess absorption = saliva is hypotonic to plasma

Question 4

Lable the 4 cell types?

Answer 4

Question 5

What are the functions of saliva?

Answer 5

• Breakdon food components
• Activate taste buds
• Produce mucus for swallowing
• Moisturiser to aid speech
• Promotes oral hygeine
• Contains bicarbonate –> neutralises acids in food reducing cavities

Question 6

What happens to ion concentrations when high salivary flow rate?

Question 7

What happens when acinar cells are parasympathetically vs sympathetically stimulated?

Answer 7

Para = + serous saliva is produced, rich in enzymes

Symp = small amount of thick saliva rich mucous produced

Question 8

What role does bradykinin have in saliva production?

Answer 8

+ bradykinin = vasodilatation = increase in saliva secretion

Question 9

What are the 2 phases of swallowing?

Answer 9

Oropharyngeal –> food bolus directed into oesophagus

Oesophageal –> oesophagus is protected from damage caused by passing food bolus via mucous secretion

Question 10

What are the 2 regions of gastric mucosa?

Where are mucosal gland cells found?

Answer 10

Oxyntic mucosa = in fundus and body of stomach

Pyloric gland area = in antrum

In gastric pits

Question 11

What is the role of parietal, cheif and surface epithelial cells in stomach?

Answer 11

Parietal = secrete HCl and intrinsic factor

Cheif = secrete pepsinogen

Surface epithelial = secrete mucous

Question 12

How do parietal cells produce HCl?

Answer 12

P takes H+ in exchange for K+

A moves carbonate into blood and Cl- into cell

C transports Cl- and K+ into gastric lumen

Question 13

What is the relationship between stomach HCl and pepsinogen?

Answer 13

HCl = provides acidic environment for pepsin to digest food

Question 14

What is the cephalic phase of gastric secretion?

Answer 14

• Gastric secretion stimulated prior to food arriving
• Stimulated by thought of expectation
• Contributes 30-50% gastric secretions
• Is dependent upon vagus nerve activity

Question 15

What is the gastric phase of gastric secretion?

Answer 15

• When food reaches stomach
• Contributes 50-60% gastric secretions
• Occurs due to local vagal reflexes in response to mechanical stimulation
• Gastrin release from G-cells stimulated by peptide fragments of partially digested proteins

Question 16

What is the intestinal phase of gastric secretion?

Answer 16

• Contributes 5% of gastric secretions
• Due to circulating AAs or gastrin

Question 17

What effect does pH and enterogastrone have on gastrin release?

Answer 17

pH < 2 = inhibition of gastrin release from G cells via somatostatin release

Enterogastrone = released when duodenum distended or chyme = inhibits gastrin release

Question 18

How are gastric mucosa protected from autodigestion?

Answer 18

Luminal membranes = H+ impermeable = connected via tight junctions = no H+ between cells

Negative feedback = pH less than 2 inhibits G-cells via somatostatin from D-cells

Mucus = release from surface epithelial cells

Rapid repair of damaged mucosa

Question 19

What is the role of duct cells, centrocinar and acinar cells in the pancreas?

Answer 19

HCO3- exchange with Cl-

Bicarbonate secretion for neutralising acid chyme

Enzyme rich alkaline secretion

Question 20

What controls pancreatic secretions?

What is the role of acetylcholine in the pancreas?

Answer 20

Vagus nerve

Potentiates actions of secretin and cholecystokinin

Question 21

What are the functions of secretin and cholecystokinin?

Answer 21

Secretin = released in repsonse to acid in duodenum –> stimulates HCO3- production

Cholecystokinin = stimulates enzyme rich secretion released in response to fat and protein in duodenum

Question 22

Wjhat is the role of somatostatin in the pancreas?

Answer 22

Inhibits pancreatic secretions

Question 23

How are carbohydrates digested in the SI?

Answer 23

• Digested as complex carb
• Digestion ceases in acidic stomach environment
• • digestion from pancreatic alpha-amylase
• Subsequent digestion by enzymes of SI brush border
• Sodium dependent process

Question 24

How are proteins digested in the SI?

Answer 24

• Digested in stomach by pepsin
• Halted by alkaline pancreatic secretions
• Endo and exopeptidases are pancreatic enzymes for digestion
• Enzymes secreted in inactive form into duodenum
• Further digestion by peptidases on brush border, fomring AAs
• Absorbed via passive diffusion or facilitated transport
• Intracellular peptidases breakdown peptides

Question 25

How are lipids digested in the SI?

Answer 25

- Digested by pancreatic lipase (water soluble) - Fats emulsified by bile acids from liver, released by gall bladder - Monoglycerides and FFAs formed from pancreatic lipase action (absorbed by forming micelle) - Triglycerides reformed intracellularly, combined with phospholipids, cholesterol and protein - Forms chylomicron - Chylomicron is transported via lymphatic system

Question 26

What are the main investigations for GI infection?

Answer 26

Grow bacteria in culture Look for specific toxins Look for parasites with microscope Attempt to detect specific antigens / antibodies

Question 27

What are problems with C. diff infection?

Answer 27

- Vegetative cells produce toxin - Can colonise and not cause disease - Antibiotics kill other bacteria, allowing C. diff to thrive - Disease = diraahoea - toxic megacolon - perforation - Metronizadole for mild disease, vancomycin for severe

Question 28

What are problems with H. pylori infection?

Answer 28

- Chronic gastritis - Bacterial - Duodenal ulcer disease = 80% - Inflammatory response - Association with gastric adenocarcinoma - Urea breath test, gastric biopsy, serology - 2 antibiotics + PPI for treatment

Question 29

What are 4 anti-emetic drugs?

Answer 29

H1-receptor antagonists Anti-muscarinic agents Dopamine antagonists 5-hydroxytryptamine antagonists

Question 30

What are 3 common causes of diarrhea?

Answer 30

Rotavirus - damages small bowel villi Invasive bacteria - damage epithelium Adhesive enterotoxigenic bacteria - adhere to brush border, + cAMP, Cl- and Na+ secretion followed by water

Question 31

When are antibiotics, orlistat, misoprostol and PPIs used in diarrhoea?

Answer 31

Antibiotics = superinfection Orlistat = Pancreatic lipase inhibitor used for steatorrhea Misoprostol = used for inflammatory type response PPIs = used in infectionq

Question 32

How do opioids help in diarrhoea?

Answer 32

Reduce tone and peristaltic movements of GI muscles Reduce ACh release + transit time + water reabsorption Symptomatic relief Can cause constipation

Question 33

How can you treat constipation?

Answer 33

Osmotic laxatives: - Lactulose - Macrologs - Magnesium Bulking agents stimulating GI activity: - Stimulant laxatives - Prucalopride

Question 34

Treatment for IBS?

Answer 34

Lactulose or loperamide Antispasmodics Amitriptyline

Question 35

How do you treat IBD?

Answer 35

Anti-inflammatories and immunosupressants - 5-aminosalicylates - Corticosteroids - Immuniosupressants