Gastrointestinal disorders Flashcards
List some examples of GIT disorders
- Peptic ulcer disease
- Osmotic and secretory diarrhoea
- Gluten and lactose intolerance
- Inflammatory bowel disorders
- Cirrhosis
- Acute pancreatitis
- Gallstones
What causes mumps?
Viral infection of the salivary glands
What is a possible consequence of mumps particular to males?
Orchitis (testicular inflammation) that may cause infertility in adult males
Name the three types of gastric exocrine cells and the substances they excrete
- Mucous cell
- Parietal cell — HCL, intrinsic factor
- Chief cell — digestive enzymes (most notably pepsinogen; converts to pepsin which breaks down proteins)
Name the three types of stomach endocrine cells and the substances they secrete
- G-cells — release gastrin into blood
- Enterochromaffin-like cells — secrete histamine (paracrine — effects only in the area of the gland secreting it)
- D-cells (found mainly in duodenum but also pyloris) — secrete somatostatin (signals body to stop producing excess acid)
Gastrin is released from G-cells in response to what?
Distension of antrum/vagus nerve stimulation
What is the function of G-cells?
Promotes secretion of HCl and pepsinogen, as well as stomach motility
What inhibits gastrin secretion from G-cells?
Low pH (<4) and the hormone somatostatin
What does omeprazole do?
Shuts down acid production by proton pump inhibitors
What prevents the stomach digesting itself?
A mucous layer trapping HCO3- (local alkaline pH), giving a neutral buffer effect.
List four protective factors of gastroduodenal mucosa
- HCO3- and mucous
- Prostaglandins
- Mucosal blood flow
- Growth factors
List six damaging factors for gastroduodenal mucosa
- H+ and pepsin
- H. pylori
- NSAIDs
- Stress
- Smoking
- Alcohol
Ulcers cannot be present without ____.
Acid
What is the main cause of peptic ulcer disease?
Helicobacter pylori infection
List three contributing factors for peptic ulcer disease
- Stress
- NSAIDs
- Alcohol
True or false: stress, NSAIDs, and alcohol are causal factors for peptic ulcer disease.
![](https://s3.amazonaws.com/brainscape-prod/system/cm/253/090/202/a_image_thumb.gif?1536479012)
How does H. pylori cause peptic ulcer disease?
H. pylori has the enzyme urease which digests urea to produce NH3. It creates a small local area with favourable pH to withstand the harsh environment of the stomach.
Explain why peptic ulcer disease is so common in the duodenum
- H. pylori infects the antrum of the stomach
- This inhibits somatostatin secretion, leading to excess gastrin secretion
- Increased H+ is delivered to the duodenum as acidic food boluses, causing the ulcer
- The duodenum normally responds by secreting HCO3-, but this is inhibited by the H. pylori infection
Name two tests used to dx peptic ulcer disease
Urea breath test and endoscopy
Explain the urea breath test
- The pt ingests urea with a small amount of radioactive carbon
- H. pylori metabolises it to NH3 and radioactive CO2
- The amount of radioactive CO2 exhaled is measured
Describe the rx for peptic ulcer disease
- Omeprazole (proton pump inhibitor)
- Antibiotics for H. pylori
What is Zollinger-Ellison syndrome?
Peptic ulcer disease caused by a tumour (gastrinoma)
Where is the gastrinoma often located?
Head of the pancreas
How does a gastrinoma cause peptic ulcer disease?
The tumour secretes large amounts of gastrin into the blood, inducing excessive H+ secretion by parietal cells
Describe three tests for dx of peptic ulcer disease that is not caused by a tumour
- Serum gastrin levels — tested after fasting on at least three separate occasions (levels should be low)
- Pentagastrin test — infusion of a gastrin homologue while H+ is monitored; normally would increase acid but if a gastrinoma already has levels extremely high there is little change
- Secretin stimulation test — secretin stimulates gastrin secretion from a gastrinoma but not from healthy G-cells, i.e. gastrin increases when a tumour is present
Small intestine absorption is predicated on what factor?
Having a large surface area