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