Lecture 3 Flashcards
What is pepsin?
It is an acidic protein in gastric juice
What happens to pepsin when the stomach empties?
It empties through the pylorus and squirts onto the duodenum which is where stomach ulcers are found
How can you stimulate acid in the stomach?
By gastrin
How many different amino acids of gastrin are there that can stimulate acid secretion?
5 amino acids
What can stimulate pepsin secretion?
Insulin
What is the major pepsin in man?
Pepsin 3
What Pepsin is more likely to degrade mucus?
Pepsin 1 - there is a 2 fold increase in pepsin 1 than pepsin 2 at pH2
What happens if the pH is 4 with pepsin?
Pepsin will have a 6-fold inference which is damaging to the mucosa
What is the gastric juice in gastric ulcers likely to do?
It can degrade the mucosal barrier
What is pepsinogen stable up to?
PH10 and 11
When does pepsin start to denature?
PH7 - it is effectively denatured (where it becomes inactive), above pH8 pepsin can’t be recovered it is irreversibly denatured
At what pH does a lot of digestion take place in gastric juice?
pH 2
What are 5 diseases associated with reflux?
GORD, OME (glue ear), LPR, rhinitis and sinusitis and vocal folds epithelial cell hyperplasia
What is a treatment for glue ear?
Put a hole in the ear drum and fit a grommet to suck out the liquid in the ear - contains a lot of mucus
What is larangomalacia?
Incomplete development of the larynx in children, collapses and it gets hard to breathe
What are the two sphincters for probe monitoring - measuring pH?
Upper Oesophageal sphincter - one probe sits outside, and an oesophageal probe which sites 5 centimetres above the lower oesophageal sphincter
What is the oesophageal sphincter also known as?
The cardiac sphincter
What is positive pharyngeal reflux event?
A drop below pH 4 at the top of the oesophagus preceded by a precipitous drop at the distal probe
Is pH4 damaging?
Yes - even if you were to put a pH of 3.5 on a living tissue it would cause cell death
Why would you look at sputum if a patient had reflux?
Because the sputum of the patient should have pepsin present
What is measured to measure the sputum sample?
A SLOT BLOT - with a nitrocellulose membrane and a vacuum system
Does pepsin increase reflux in a higher pH?
Yes from pH2 to Ph5 there are more reflux events as pH is increased.
What is the highest pH that pepsin can work at?
PH6.5 , 50% of activity is at pH 3.5
what are two techniques that can be used to measure functional pepsin?
ELISA technique and an activity assay
what is the standard diagnosis of reflux?
24 hour double-probe pH monitoring
