3: Salivary and gastric secretion, gastric motility Flashcards
What are the three pairs of major salivary glands?
Parotid glands
Submandibular glands
Sublingual glands
Which salivary gland produces thick, viscous mucous?
Sublingual glands
What is a functional unit of a salivary gland?
Salivon
Salivary glands secrete saliva via a system of ___.
ducts
Which type of cell within a salivon produces the saliva before it is secreted through ducts?
Acinus (acinar cell)
What are the two types of acinar (excretory) cells found in a salivon?
Serous cells
Mucous cells
What enzyme is found in the watery excretions of serous cells?
Alpha amylase
What is produced by mucous cells?
Thicker mucous
What is the purpose of lysozymes?
Break down the cell walls of bacteria
Water and mucus ___ the oral cavity, allowing speech and swallowing.
lubricates
Is the oral cavity alkaline or acidic?
Why?
Alkaline
Saliva contains bicarbonate ions
Saliva contains high levels of Ca2+ - what does this serve to protect?
Tooth enamel
The protective aspects of saliva serve to kill ___.
bacteria
Alpha amylase from the saliva can continue to digest the food for over ___ minutes.
30
What deactivates amylase once it has reached the stomach?
Hydrochloric acid
Saliva is produced in a greater volume before emesis - what is emesis?
Vomiting
In which cells of a salivary gland does secretion of saliva occur?
In which cells does modification occur?
Acinar cells
Duct cells
What is the unconditional salivary reflex?
Secretion of saliva triggered by the presence of food in the mouth
Which receptors trigger the unconditional salivary reflex?
Chemoreceptors
Mechanoreceptors
detecting the presence of food and the chemicals in it
What is the conditional salivary reflex?
Increase in secretion caused by thinking about, smelling, seeing or hearing about food
The conditional salivary reflex is (inherent / learned).
learned
Which cranial nerves are involved in saliva secretion?
CN VII and IX
Facial nerve and Glossopharyngeal nerve
Which arm of the ANS causes the secretion of a large volume of watery, enzyme-rich saliva?
Parasympathetic
When does parasympathetic secretion of saliva occur?
Normal resting conditions
Which arm of the ANS causes the secretion of thick, viscous saliva?
Sympathetic
When does sympathetic secretion of saliva occur?
Times of stress
What is ingested food called once it has been mixed with gastric secretions in the stomach?
Chyme
In the first 30 minutes after a meal, chyme is moved to the ___ of the stomach by peristalsis.
antrum
Which sphincter separates the stomach from the duodenum?
Pyloric sphincter
Gastric mucosa is resistant to ___ but damaged by ___.
acid
bile
Regurgitation of bile through the pyloric sphincter can cause peptic ___.
ulcers
Stomach emptying is determined by the __ and __ of the chyme.
volume
consistency
Volume and consistency of chyme influence how ___ the stomach becomes after a meal.
distended
By which two means does the duodenum control when chyme is passed to it from the stomach?
Neuronal means
Hormonal means
In which area of the stomach are pyloric glands found?
Antrum
Gastrin and somatostatin are two hormones released by the pyloric glands - what do they do?
Gastrin stimulates HCl secretion
Somatostatin inhibits HCl secretion
From which pyloric gland cell is gastrin released?
From which pyloric gland cell is somatostatin released?
Gastrin is released from G cells (easy enough)
Somatostatin is released from D cells (just because)
In which areas of the stomach is oxyntic mucosa found?
Fundus
Body
Which oxyntic mucosa cells secrete hydrochloric acid and intrinsic factor?
Parietal cells
What does intrinsic factor do?
Binds to Vitamin B12 to facilitate its digestion later
What is released by Chief cells in the oxyntic mucosa?
Pepsinogen
(precursor to pepsin which is activated by HCl)
Which enzyme is important in the secretion of hydrochloric acid from gastric parietal cells in the oxyntic mucosa?
Carbonic anhydrase
Which signal molecule is the strongest agonist for hydrogen ion secretion?
Histamine
What effects do
a) PPIs (e.g omeprazole)
b) prostaglandins
c) muscarinic antagonists
d) H2 antagonists
have on the secretion of HCl by parietal cells?
a) PPIs = DECREASE
b) Prostaglandins = DECREASE
c) MUSCARINIC ANTAGONISTS = DECREASE
d) H2 ANTAGONISTS = DECREASE
What are some classes of drugs which influence acid secretion?
NSAIDs like aspirin
Proton-pump inhibitors - e.g omeprazole
Histamine receptor antagonists
Muscarinic receptor antagonists
What is a gastric side-effect of NSAIDs (e.g aspirin)?
Peptic ulcers
Why do NSAIDS cause peptic ulcers?
Impair prostaglandins (which reduce HCl secretion) and other mechanisms of mucosal protection
Allowing digestion of epithelium by HCl and pepsin
Which bacteria is associated with peptic ulcers?
H. pylori
Proton-pump inhibitors (increase / reduce) gastric secretion.
Give an example of a PPI.
reduce
omeprazole
What is an example of a histamine receptor antagonist which reduces gastric secretion of HCl?
Ranitidine
