GIT Flashcards
What do the salivary glands secrete?
Amylase
lipase
mucin
What is the role of mucin?
Aids lubrication and swallowing of material
What are the 3 sets of salivary glands called?
Sublingual
Submandibular
Parotid
Which virus infects the salivary glands, in particular the parotid glands?
Mumps
What is dysphagia and how is it caused?
Difficulty swallowing - caused by damage to nerves
What is the function of the lower oesophageal sphincter?
Contract and seal the top of the stomach to prevent acid from passing into oesophagus
What is Barret’s oesphagus?
When normal squamous epithelial cells are replaced with abnormal specialised columnar cells which are cancerous. This happens as a result of cells being exposed to stomach acid
Patients with Barrett’s oesophagus are less likely to get adenocarcinoma. True or false?
False - at increased risk - even if reflux is controlled and the oesophagus heals - the cancerous cells remain
What do g cells secrete?
gastrin - this stimulates secretion of acid
Where are G-cells found?
In the stomach antrum
Where are chief cells found?
in the stomach fundus/body
What do chief cells secrete?
Pepsinogen and lipase
What do the parietal cells secrete?
Acid (HCl)
What is the role of gastric lipase?
Converts triglycerides into monoglycerides
What are the 4 types of gastric cells?
Mucous cells
G cells
Chief cells
Parietal cells
Pepsinogen is converted into pepsin when it comes into contact with what?
HCl
How are H2 receptors involved in the secretion of gastric acid?
Stretch of the stomach upon entry of food causes the release of histamine which binds to histamine receptors and causes the release of HCl
What are the ways in which gastric acid is produced in the stomach?
proton pump secretes acid
site and smell of food triggers receptors and impulses go into brain. The brain fires impulses down neurone into stomach. When these arrive in stomach, ACh is released and binds to receptor causing release of HCl from parietal cells
G-cells produce gastrin which stimulates release of HCl
Stretch of stomach upon entry of food releases histamine and causes release of HCl
What are the drug classes that can reduce stomach acid secretion?
H2 receptor antagonists
PPIs
Name a H2 receptor antagonist
Ranitidine
Climetidine
Name a PPI
Omeprazole
Proton pump inhibitors reversibly bind to SH group of the proton pump. True or false?
False - irreversibly bind
What is the role of carbonic anhydrase in a parietal cell?
It catalyses the combination of carbon dioxide and water to form carbonic acid
It also splits carbonic acid into bicarbonate and protons
What prevents the stomach form digesting itself?
Pepsinogen (pepsin protease secreted in the inactive form)
The stomach secretes HCl. What 3 factors prevent the stomach from suffering from burns as a result?
Mucus secretion
Tight junctions
High cell turnover throughout the GIT
How does mucus protect the stomach from acidic conditions:?
It is alkaline so neutralises acid. It forms a barrier, stopping pepsin getting through and digesting underlying tissue
What is the role of tight junctions in the stomach?
They lock epithelial cells together and so restrict movement of acid/protease to underlying tissue
Why is the high cell turnover throughout the GIT beneficial to the stomach?
damaged cells are frequently replaced with cells from gastric pits
What is peritonitis and how is it caused?
Inflammation of the lining of the peritonea as a result of a bacterial infection due to perforated ulcer
Peritonitis is a medical emergency and requires hospitalisation. True or false?
True
How can H.pylori lead to ulcer formation?
It infects the gastric mucosa leading to a decrease in barrier efficiency leading to ulcer formation
What are the 3 surgical procedures for obesity?
Gastric sleeve
Gastric band
Roux en Y bypass
What is peristalsis?
Wave of muscular contraction that pushes material in the lumen along the intestine
How does targeting longitudinal muscles help in treatment of diarrhoea?
Retain contents in GIT longer so there is an increase in water absorption and the consistency of contents changes