GIT physiology Flashcards
what are migrating myoelectric complex stimulated by?
1. _____ (increase/decrease) in chyme pH
2. _____ (increase/decrease) in plasma [motilin]
- increase in chyme pH
- increase plasma [motilin]
what is migrating myoelectric complex replaced by when a meal enters the stomach?
segmenting/mixing contractions
what are the 3 phases of swallowing?
- buccal (voluntary)
- pharyngeal (involuntary)
- oesophageal (involuntary)
which part of the brain controls the buccal phase of swallowing?
cerebral cortex
which part of the brain controls the pharyngeal and oesophageal phases of swallowing?
medulla (brainstem)
what are the functions of migrating myoelectric complex?
- move undigested remains to large intestine
- prevent overgrowth of bacteria
what are the 3 extrinsic salivary glands?
- parotid gland (largest)
- submandibular gland
- sublingual gland (smallest)
what is the function of mucin in the saliva?
lubrication of food
what is the enzyme present in saliva for carbohydrate digestion?
amylase (ptyalin)
what is ptyalism?
excessive salivation
what is xerostomia?
dry mouth (insufficient salivation)
what is the function of pepsin?
initiate protein digestion in stomach
what is the function of intrinsic factor?
allows absorption of vitamin B12
what do parietal cells secrete?
HCl and intrinsic factor
what do chief cells secrete?
pepsinogen
what do enterochromaffin-like cells secrete?
histamine
what do G cells secrete?
gastrin
what do D cells secrete?
somatostatin
what are the 4 types of secretory cells in gastric glands?
- mucus cells
- parietal cells
- chief cells
- enteroendocrine cells
why can’t unconjugated bilirubin be renally excreted?
it is not water soluble; fat soluble
what is the function of bile salts?
emulsify fats in small intestine
what is lecithin?
phospholipid that combines with bile salts to emulsify fats
what do acinar cells of the pancreas secrete?
pancreatic enzymes (synthesised in zymogen granules)
which enzyme initiates activation of pancreatic enzymes?
membrane-bound enterokinase
what enzyme converts trypsinogen to trypsin?
enterokinase
what hormone is released in response to fat and protein in the duodenum?
cholecystokinin
what do acinar cells secrete in response to increase cholecystokinin?
digestive pancreatic enzymes
what stimulates ductal cells of the pancreas to increase bicarbonate secretion?
increase secretin in response to acidic chyme
what type of jaundice would have normal urine and stool colour?
pre-hepatic jaundice
what type of jaundice presents with dark urine and pale stools?
cholestatic/post-hepatic jaundice
what type of jaundice presents with dark urine and normal stools?
mixed/intra-hepatic jaundice
which part of the hypothalamus controls appetite?
arcuate nucleus
does ghrelin promote or inhibit hunger?
promote
which hormone inhibits hunger?
leptin
what is required for the activation of pepsin from pepsinogen?
HCl to achieve optimal pH2
what types of contractions are triggered by the filling of your stomach?
segmenting contractions (small intestine)
mass movements (large intestine)
what are the main substances absorbed in the duodenum, jejunum and ileum?
duodenum: iron
jejunum: folate
ileum: vitamin b12
Which of the following mediators can suppress gastrin/histamine regulation of gastric acid secretion?
a. prostaglandin
b. dopamine
c. ACh
d. amoxicillin
prostaglandin
prostaglandin and somatostatin inhibits gastric acid secretion
Which of the following enzymes does the pancreas secrete in its inactive (precursor) state?
a. cholesterol elastase
b. chymotrypsin
c. lipase
d. amylase
b. chymotrypsin
