Physio Pre ICA Flashcards
What does the lower oesophageal sphincter do?
It relaxes to accommodate the bolus.
It protects against gastroesophageal reflux.
What does the fundus of the stomach do?
It produces HCL, pepsinogen, intrinsic factor, and lipase.
What does the antrum of the stomach do?
It produces peptide hormone gastrin and is involved in the mixing and grinding of chyme
What does the parietal cells in the gastric gland secrete?
Acid and intrinsic factor.
What does the ECL cells in the gastric gland secrete?
Histamine.
What does the chief cells in the gastric gland secrete?
Pepsinogen.
After meal stimulation, what is the ionic change that happens in the gastric juice?
Increase in chloride and hydrogen ion. (HCL)
Decrease in potassium, sodium, and bicarbonate.
Hydrochloric acid is hypotonic or isotonic?
Isotonic.
The tubulo-vesicles of the parietal cell are stimulated by which hormones?
Acetylcholine and histamine.
What happens when the tubulo-vesicles fuse into secretory canaliculi?
They pump hydrochloric acid out of the cell and into the gastric gland/lumen of the stomach.
What does carbonic anhydrase release during parietal secretion?
It releases carbonic acid from water and carbon dioxide.
What happens when the carbonic acid dissociates during parietal secretion?
The hydrogen leaves in exchange for potassium.
The bicarbonate leaves, and the urine becomes alkaline because of the bicarbonate.
What does acetylcholine stimulate in motor neurones?
The release of pepsinogen from chief cells.
The release of histamine from ECL cells.
The release of HCL from parietal cells.
What does the cholinergic (GRP) stimulate during vagal outflow?
The release of gastrin from G cells.
What are the three factors that stimulate gastric secretion?
The hormone gastrin, Histamine, and acetylcholine.
From which type of cells is gastrin secreted?
Antral G cells.
When gastrin is secreted, how does it stimulate acid secretion?
Gastrin stimulates the release of histamine from ECL cells. Histamine stimulates acid secretion.
If the body wants to prevent overstimulation of gastric acid, which hormone does it produce?
Somatostatin.
Somatostatin comes from which type of cells?
D cells.
Somatostatin blocks which hormone?
It blocks the secretion of gastrin.
What happens when low antral pH is low?
Somatostatin is released.
What is glycoprotein mucin?
It is the most important part of mucus. It is hydrolysed by pepsin.
How is pepsin formed in the gastric juice?
Low pH causes the cleavage of pepsinogen into pepsin.
What is the importance of intrinsic factor?
It helps absorb vitamin B12.
What does vitamin B12 bind to when ingested?
Haptocorin.
What happens when haptocorin is released from vitamin B12?
Vitamin B12 bind to intrinsic factor.
What happens when parietal cells stop functioning?
Malabsorption of vitamin B12. (also happens in destruction of terminal ileum)
What are the interstitial cells of cajal?
They are the pacemaker cells for generation of slow waves.
Gastric emptying is faster for liquid meals or solid meals?
Liquid meals.
Why must we chew food?
Because some foods have a cellulose membrane.
Chewing muscles are innervated by which nerve?
Trigeminal.
What are the three salivary glands?
Parotid, sublingual and submandibular
What does the parotid gland do?
It is a serous only and is high in amylase.
What does the sublingual and the submandibular glands do?
Secrete both mucus and serous.
What does the von ebner gland do?
Secrete serous and is high in lipase.
What does the buccal gland do?
Secretes mucus only.
Saliva is hypotonic or isotonic?
Hypotonic.
Which ions are high in saliva?
Potassium and Bicarbonate.
What ions are low in saliva?
Chloride and Sodium.
What is another name of pancreatic islets?
Islets of langerhans.
What are ions that are high in plasma?
Chloride and Sodium.
What are ions that are low in plasma?
Potassium and Bicarbonate.
Why does tonicity of saliva increase with flow rate?
It becomes hypotonic because chloride gets reabsorbed from the saliva and into the duct.
What ions are high and low in the acini?
High - Chloride and Sodium.
Low - Potassium and bicarbonate.
What makes the saliva alkaline?
Bicarbonate.
What ions are the ducts in the saliva rich in?
Potassium and Bicarbonate.
What is the function of the constituent mucin?
Lubrication.
What is the function of the constituent lipase?
Fat digestion.
What is the function of the constituent amylase?
Starch digestion.
What is the function of the constituent IgA?
Immune protection.
What is the function of the constituent growth factor?
Wound healing.
What is the function of the constituent lysozyme?
Antibacterial.
What is the propulsive role of the upper oesophageal sphincter?
Relaxes to allow food to enter the oesophagus.
What is the propulsive role of the lower oesophageal sphincter?
Relaxes to allow the bolus to enter the stomach.
What is the protective role of the upper oesophageal sphincter?
Protects airway from swallowed material.
What is the protective role of the lower oesophageal sphincter?
Protects oesophagus from acid reflux.
Which neurotransmitters stimulate the contraction of circular muscle layer in the oesophageal wall?
Acetylcholine and Substance P.
Which neurotransmitter relaxes the longitudinal muscle layer in the oesophageal wall?
Nitric oxide and maybe VIP.
What triggers the relaxation of the lower oesophageal sphincter?
Nitric oxide, VIP, CCK, and gastrin.
What causes the contraction of the circular muscle layer above the bolus?
The production of acetylcholine and substance P.
What causes the relaxation of the circular muscle layer below the bolus?
Nitric oxide and VIP.
What causes the relaxation of longitudinal muscle layer above the bolus?
The release of nitric oxide and VIP.
What causes the contraction of the longitudinal muscle layer below the bolus?
Acetylcholine and substance P.
Why is ischemic injury more likely in the mucosa of the gut wall?
Because blood flows through the muscularis and submucosal layers before it reaches the mucosa, oxygen content is normally low in the villi
What are examples of mediators in the endocrine mechanism of the GIT?
CCK, Secretin, Gastrin.
What are examples of mediators in the neurocrine mechanism in the GIT?
Acetylcholine, VIP, GRP.
What are examples of mediators in the paracrine mechanism of the GIT?
5HTP, Somatostatin, Histamine.
What is the function of the hormone gastrin in the GIT?
Stimulates the release of gastric acid pepsinogen from the stomach.
What is the function of the hormone CCK in the GIT?
Stimulates the release of bile from the gallbladder and pancreatic enzymes from the pancreas. It also helps to slow down gastric emptying.
What is the function of the hormone secretin in the GIT?
Stimulates the release of bicarbonate from the pancreas and bile from the liver. It also helps to neutralize stomach acid
What is the function of the hormone GLP-1 and GIP in the GIT?
Stimulates the release of insulin from the pancreas and helps to regulate blood sugar levels. It also slows down gastric emptying and increases satiety.
What is the function of the hormone motilin in the GIT?
Stimulates the contraction of the muscles in the small intestine, which helps to move food through the digestive system.
What is the function of the hormone somatostatin in the GIT?
Inhibits the release of several other gastrointestinal hormones, including gastrin, CCK, secretin, and GIP.
What is the function of the hormone ghrelin in the GIT?
Stimulates appetite and helps to regulate energy balance.
What is the function of the hormone PYY in the GIT?
Inhibits appetite and helps to regulate blood sugar levels
Pancreatic and biliary secretion are stimulated by what in the duodenal response?
Secretin.
Why add bicarbonate into the lumen of the duodenum?
To neutralize gastric acid.
What does CCK stimulate the secretion of in the liver?
The secretion of bile.
The bicarbonate then leaves out the luminal side of the pancreatic ductal cell in exchange for what?
Chloride.
The hydrogen ion leaves the pancreatic ductal cell into the bloodstream in exchange for what?
Sodium.
Where does the pancreatic ductal cell get bicarbonate from?
Production of carbonic acid from CO2 and H2O, in the presence of ATP carbonic anhydrase produces carbonic acid, which then dissociates.
Why is pancreatic juice alkaline?
Because of bicarbonate secretion and chloride absorption.
What ions are in high concentrations in pancreatic juice?
Bicarbonate and Sodium.
Why is secretin secreted into the duodenal mucosa by S cells?
Secretin is stimulated by the low pH, it triggers the release of bicarbonate from the pancreatic ducts.
Which produces more secretin, meal or IV?
Meal.
If you combine secretin with CCK, what will happen?
A dramatic increase in secretin production.
Does CCK stimulate the release of secretin?
No.
If you combine acetylcholine with bicarbonate, what will happen?
A dramatic increase in bicarbonate.
What is the release of CCK stimulated by?
Amino acids, fatty acids, little polypeptide.
What causes relaxation of sphincter of Oddi?
VIP and NO.
What does the pancreatic ganglia produce to stimulate acinar cell secretion?
GRP, Ach, VIP.
Which hormones are responsible for the incretin effect?
GIP & GLP-1.
When are GIP & GLP-1 released?
When the glucose levels are high. This prevents hypoglycaemia.
Which hormone increases the volume of bile?
Secretin.
What keeps the cholesterol soluble?
Lecithin, bile salts, and high pH.
Where does bile salts reabsorption happen?
Ileum.
What is absorbed in ileum?
Vitamin B12.
CCK stimulates what?
Gall bladder contraction and sphincter of oddi relaxation.
What hormones are secreted in the upper small intestine?
Bicarbonate, CCK, and secretin.
Where would digestion and absorption normally occur in the small intestine?
In the upper small intestine.
What can be absorbed in the upper small intestine?
Calcium and iron.
At which phase would peristalsis occur in the small intestine?
The interdigestive phase.
At which phase would segmentation occur in the small intestine?
The digestive phase.
Which hormones are absorbed in the distal small intestine?
Vitamin B12 and Bile salts.
What would the distal small intestine secrete?
PYY and GLP.
Which hormone stimulates the migrating motor complex?
Motilin.
Which hormones contribute to motilin suppression?
CCK and GIP.
What stimulates the muscularis mucosae?
The submucosal plexus.
What do the crypts of luberkuhn secrete?
Chloride and bicarbonate.
Where would digestion and absorption occur in the intestinal villi?
At the tip of the villi.
Where would secretion occur in the intestinal villi?
At the base of the villi.
What stimulates brunner’s glands secretion?
Secretin and VIP.
What is SGLT-1 responsible for?
Active transport of glucose and galactose into the cells.
What is sodium enhanced by?
Aldosterone.
