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25 Cards in this Set
- Front
- Back
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Role of histamine?
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1. mediates allergic reactions when released from mast cells and basophils
2. control of gastric acid secretion 3. neurotransmitter 4. regulate microcirculation 5. tissue growth and repair |
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Actions of angiotensin II?
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potent vasoconstrictor that acts as a pathophysiologic mediator in hypertension and CHF
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Where is histamine principally found?
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in the lungs, nasal mucous membranes, and skin
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What are the 5 effects mediated by histamine?
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1. increase capillary Permeability
2. dilate Arterioles, capillaries 3. stimulate Nerve endings (these 3 are the Lewis Triples response: "Lewis CAN") 4. contrict bronchioles 5. stimulate gastric acid secretion |
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What do 1st generation H1 blockers do?
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treat allergies and cross BBB to treat motion sickness
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What do 2nd generation H1 blockers do?
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treat allergies, but don't cross BBB
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What do H2 blockers do?
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inhibit gastric acid secretion to treat duodenal ulcers and gastric hypersecretory states; also used in diagnosis
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What is cromolyn sodium?
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inhibits histamine release from the mast cell; prevents antigen-mediated release of granules, so used prophylactically to treat bronchial asthma and seasonal rhinitis
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What is angiontensinogen?
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protein made in liver, converted to angiotensin I by renin; renin is stimulated by decreased BP or renal perfusion
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What is angiotensin II and how is it made?
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ACE (angiotensin converting enzyme) in the luminal surface of the vascular endothelium of the lung converts angiotensin I to angiotensin II; causes vasoconstriction of arteries and veins, increases aldosterone release (retain Na+ and water), potentiates NE's pressor effects, increases ADH release
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What do ACE-inhibitors do?
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bind to the enzyme, causing dilation of arterioles, venules, and large arterial vessels; also potentiates actions of bradykinin, which reduces vascular resistance and causes natiuresis and diuresis; DOC in hypertension and CHF
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Side effects of ACE-inhibitors?
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cough, angioedema, hyperkalemia, rash, and proteinuria
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What do angiotensin II antagonists do?
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similar actions to ACE-inhibitors, but less side effects
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Which substances increase angiotensinogen release?
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glucocorticoids, thyroid hormone, angiotensin II
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Name an H2 agonist and its clinical use?
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betazole, to use as diagnostic agen for gastric acid secretion
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Name 4 first generation H1 blockers.
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1. diphenhydramine
2. chlorpheniramine 3. meclizine 4. promethazine |
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How are the H1 blockers metabolized?
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via cytochrome p450 in the liver; don't affect gastric acid secretion or bronchioles
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What are 3 typical 2nd generation H1 blockers? How are they metabolized?
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1. cetirizine
2. loratadine 3. fexofenadine Also metabolized via cytochrome p450. |
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What are 2 H2 blockers and their effects? Side effects?
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cimetidine and rantidine, which inhibit basal and histamine induced gastric acid secretion; cimetidine is a potent p450 inhibitor and decreases renal excretion of creatinine
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Name 3 ACE inhibitors
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1. captopril
2. enalapril 3. lisinopril |
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Name an angiotensin II receptor antagonist.
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1. losarten
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What are the 2 main functions of ACE?
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1. generate angiotensin II
2. degrade the peptide, bradykinin |
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What is the rate-limiting step in angiotensin II production?
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renin
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When is renin secreted?
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1. lower BP
2. sympathetic nervous system stimulation |
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Effects of bradykinin?
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release of PGI2 and NO, which reduces vascular resistance; also causes natiuresis and diuresis
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