L11 Secretion in GIT

Question 1

which nerves stimulate salivary glands?

Answer 1

parasymp cranial 7 + 9

Question 2

what does the stomach secrete?/gastric secretions

Answer 2

1. MUCUS
   - surface epithelial cells
   - glycoprotein, forms gel with water - protective layer over epithelium
2. BICARBONATE
   - surface epithelial cells
   - trapped in mucus layer, protective against acid.
3. HYDROCHLORIC ACID
   - from parietal cells
4. INTRINSIC FACTOR
   - protection of vit B12
   - from parietal cells
5. PEPSINOGENS
   - from chief cells
   - commences protein digestion

Question 3

what to parietal cells of the stomach secrete?

Answer 3

hydrochloric acid and intrinsic factor

Question 4

what to chief cells of the stomach secrete?

Answer 4

pepsinogens

Question 5

what to surface epithelial cells of the stomach secrete?

Answer 5

bicarbonate and mucus

Question 6

what is endopeptidase?

Answer 6

enzyme which hydrolyses specific bonds within a protein

Question 7

what is exopeptidase?

Answer 7

enzyme which hydrolyses terminal peptide bonds to generate free amino acids

Question 8

what stimulates gastric secretion?

Answer 8

1. Ach (released from vagus nerve and local intrinsic nerves)
2. Gastrin (released from G cells of astral mucosa)
3. Histamine (strong secretory response - synergistic)

Question 9

Phases of gastric secretion?

Answer 9

1. CEPHALIC (head)
   - triggered by: thought/smell/sight/taste of food
   - vagus nerve (Ach) - causing release of acid, pepsin and gastrin (from astral G cells)
2. GASTRIC (stomach)
   - triggered by: distension of stomach wall
   - release of gastrin (G cells antrum), inc acid and pepsin secretion.
3. INTESTINAL
   - triggered by: emptying stomach, decreased pH in gastric antrum
   - release of hormones which inhibit gastric secretion (secretin, CCK, gastric inhibitory peptide)

Question 10

what is peptic ulcer disease?

Answer 10

PUD
- protective mechanisms of epithelium of GIT fail -> sub epithelial cells become inflamed/damaged (digested) by acid ad pepsins

Question 11

common causes of peptic ulcer disease?

Answer 11

• too much acid/pepsin/histamine
• anti-inflammatory drugs
• helicobacter pylori infection

Question 12

How to treat peptic ulcer disease?

Answer 12

• antibiotics (infection)
• change medication (anti-inflammatory drugs)
• block acid secretion w/proton pump inhibitors (e.g. LOSEC, ZANTAC)

Question 13

what is zollinger ellison syndrome?

Answer 13

• increased levels of gastrin
• results in excess basal, stimulated acid and pepsin secretion, hypertrophy of gastric mucosa, ulceration, abnormal motility.