B4 Regulation of Parietal Cells Flashcards
Draw the diagram
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Explain parasympathetic control of the parietal cells
- agonist or antagonist?
- what NT and where from?
- what kind of receptor?
- what activates the proton pump?
Acetylcholine released by vagus nerve
ACh acts on muscarinic M3 receptor as an agonist
The M3 receptor is a G protein coupled receptor (GPCR)
Calcium dependent
What type of mediator is histamine and what is it responsible for?
Endogenous mediator
Responsible for skin rashes and gastric acid secretion
What kind of receptor is a histamine receptor?
What are the two types and how do they differ?
GPRCs
Histamine H1 receptor: allergy
Histamine H2 receptor: gastric acid secretion - antagonists used to treat dyspepsia
Revisit the diagram for H2 receptors
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What is gastrin?
What phase does it regulate?
Released by what?
Peptide hormone released by antral cells to mediate gastric phase
Gastrin is an agonist acting on what?
Choleystokinin CCK2 receptors
What activates the proton pump when induced by gastrin?
Calcium dependent
What activates the proton pump when induced by histamine?
cAMP (adenylyl cyclase)
Where are prostanoids derived from?
Arachidonic acid
Where is arachidonic acid located and what releases it?
Held in cell membranes and released by phospholipase A2 (PLA2)
What do cycloocygenase pathways lead to?
Prostanoids
What is the function of prostanoids and parietal cells?
Inhibit increase in cAMP
Supress proton pump activity
Cytoprotection: release mucous and bicarbonate
What do NSAIDs inhibit?
Cyclooxygenase
What is the function of the proton pump?
H+ out of cell
K+ in to cell
Activated by phosphorylation (cAMP) and calcium
