4. Peptic ulcer. Stress-ulcer in the elderly

Peptic ulcer disease?

Patient has one or more peptic ulcers in the stomach or duodenum

What is peptic ulcer disease associated with?

- H.pylori infection

- NSAID abuse

- Stress

- Cushing syndrome

- Zollinger-Ellison syndrome (rare)

Zollinger-Ellison syndrome?

Gastrin-producing tumor that is often located in the pancreas

- The tumor is not affected by negative feedback that usually prevents oversecretion so hyperacidity of the stomach occurs

= Causes treatment-resistant peptic ulcers

Defense mechanisms of the stomach against acid and pepsin?

Protective measures the stomach has to prevent ulcers to occur:

- High cell turnover

- Mucin production

- Bicarbonate secretion

- Good blood flow

- Normal motility

- Restitution

All these factors depend on prostaglandins functioning properly

Pain related to duodenal and gastric ulcers?

Duodenal ulcers - relieved by food

Gastric ulcer - pain made worse by food

How many liters of gastric juice is produced everyday?

Gastric mucosa produce 1,5-2L of gastric juice everyday

Parietal cells of stomach?

Produce HCl and intrinsic factor

Chief cells of stomach?

Secrete pepsinogen

What does gastric juice contain?

HCl, mucus, pepsin, K+, Na+ & Cl-

Properties of gastric juice?

Pepsin in gastric juice is strictly not necessary for protein digestion, as pancreatic trypsin can take over the job

- Little or lack of gastric juice does not directly impair the digestion

However, gastric juice is not useless; it has important antibacterial properties

Basal Acid Output (BAO)?

Total gastric secretion DURING UNSTIMULATED, FASTING STATE

- Gastric juice: 30-40mL/hour, containing 1-4 mEq acid

Maximal acid output (MAO)?

Is 5-10 times higher than BAO, and is evoked by a drug called pentagastrin

How is the pH of gastric content?

pH og gastric content 1.5-4.0 (even after being mixed with food)

- The low pH is essential for the conversion of pepsinogen to pepsin

- Acidic pH inhibits gastrin secretion by negative feedback

What can stimulate HCl?

- Histamine paracrinally

- Gastrin endocrinally

- Acetylcholine as a neurotransmitter

Conditions where gastric juice is higher or lower than normal?

Achylia gastrica - No production of gastric juice

Hyperchlorhydria - HCl content is higher than normal

Hypochlorhydria - HCl is lower than normal

Achlorhydria - HCl is absent

What happens to gastric juice production if gastric mucosa undergoes atrophy?

- HCl secretion will become impaired first

- Then pepsinogen production

- Lastly the Intrinsic Factor

Peptic ulcer?

Tissue defect that reaches at least into the submucosa

- Frequently even deeper

More superficial damage = erosion

Peptic ulcer is a common disease with severe consequences

- Frequently occur in the stomach, but may also occur in the duodenum

When does a peptic ulcer develop?

When the balance between the aggressive factors (acid & pepsin) and the defensive factors are disturbed

Why is good blood flow essential?

"Washes out" any acid that diffuses into the interstitium quickly

- Also provides a steady supply of bicarbonate

Decreased perfusion is seen in elderly, which contributes to the formation of "stress-ulcers" by them

Function of prostaglandins in the stomach?

Increases:

- Mucin production

- Perfusion

- Enhance bicarbonate secretion

- Inhibit acid secretion

Restitution?

Refers to the intact cells ability to spread to and cover an injured area, to protect it from further injury.

= Depends on:

- Good circulation

- An intact basement membrane

(Therefore is not possible in deeper injuries)

What are the risk factors for developing peptic ulcers?

- NSAIDs -> inhibit COX, the enzyme producing prostaglandin

- Ethanol -> causes vascular injury, increases HCl secretion & is cytotoxic in high concentrations

- Smoking -> increases HCl secretion, decreases mucosal perfusion

- Corticosteroids -> if combined w/ NSAIDs

- Coffee, tea, cola -> increases HCl production

- Shock, trauma, burns, stress -> decrease mucosal perfusion

- Helicobacter pylori

H.pylori?

Famous bacteria to cause peptic ulcers:

- Produces enzyme urease - breaks down urea into -> NH3, neutralizing the acid around it

- It uses flagella to dig into the mucus layer, where it is protected from the stomach acid

- It produces toxins that are cytotoxic to the mucosal cells