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agonists, his def
drugs that bind to physiological receptors make them do the same things as would the endogonous things that would bind to said receptors
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agonists, his def
drugs that bind to a receptor and interfere with whatever the endogonous things that bind there would like to make happen
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partial agonists or antagonists
drugs that are only partly effective as ant/agonists
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efficacy
capacity to stimulate or produce an effect for a given receptor occupancy
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potency
DOSE required to produce a given effect
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if a drug acts on a receptor that serves functions common to most cells, its effects ...
will be widespread
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if a drugs's function is pretty vital, what else do you know about the drug?
it's pretty difficult or dangerous to use
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what do you know about a drug that interacts with unique receptors?
its effects are pretty specific
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histamine or histamine-like agents (2-methylhistamine) -- how do the affect the cardiovascular system via H1 receptors?
- vasodilation -- reduction of peripheral resistance & decrease in BP
- increased capillary permeability & formation of edema
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histamine or histamine-like agents (2-methylhistamine) -- how do the affect the extravascular smooth muscle via H1 receptors?
bronchospasm in pts w bronchial asthma (less pronounced affect in normal pts)
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where are histamine H1 receptors found
many tissues (vascular, respiratory)
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where are histamine H2 receptors found
parietal cells of stomach mucosa
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activation of H2 receptors by histamine or agonist 4-methylhistamine may cause...
- increased gastric acid secretion
- (to a lesser extent) secretion in small and large intestine
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where are histamine H3 receptors? _ _ _
predominantly presynaptic - located in the brain, plexus myentericus, and other neurons
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what can activate H3 receptors?
histamine, norepinephrine, serotonin, acetylcholine (possibly by a decrease in Ca influx)
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3 ways to limit the effects of histamine
- physiologic antagonists: (they act at diff receptors and have smooth muscle actions opp to histamine. important in systemic anaphylaxis induced by histamine -- epinephrine)
- release inhibitors: reduce degranulation of mast cells (degran would release histamine into body) that result from IgE binding to mast cells during allergic responses .. cromolyn - reduces bronchospasm
- receptor antagonists: H1,2,3 antagonists
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cromolyn
- a release inhibitor that reduces degranulation of mast cells
- it reduces bronchospasm
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