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25 Cards in this Set

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Role of histamine?
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
Actions of angiotensin II?
potent vasoconstrictor that acts as a pathophysiologic mediator in hypertension and CHF
Where is histamine principally found?
in the lungs, nasal mucous membranes, and skin
What are the 5 effects mediated by histamine?
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
What do 1st generation H1 blockers do?
treat allergies and cross BBB to treat motion sickness
What do 2nd generation H1 blockers do?
treat allergies, but don't cross BBB
What do H2 blockers do?
inhibit gastric acid secretion to treat duodenal ulcers and gastric hypersecretory states; also used in diagnosis
What is cromolyn sodium?
inhibits histamine release from the mast cell; prevents antigen-mediated release of granules, so used prophylactically to treat bronchial asthma and seasonal rhinitis
What is angiontensinogen?
protein made in liver, converted to angiotensin I by renin; renin is stimulated by decreased BP or renal perfusion
What is angiotensin II and how is it made?
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
What do ACE-inhibitors do?
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
Side effects of ACE-inhibitors?
cough, angioedema, hyperkalemia, rash, and proteinuria
What do angiotensin II antagonists do?
similar actions to ACE-inhibitors, but less side effects
Which substances increase angiotensinogen release?
glucocorticoids, thyroid hormone, angiotensin II
Name an H2 agonist and its clinical use?
betazole, to use as diagnostic agen for gastric acid secretion
Name 4 first generation H1 blockers.
1. diphenhydramine
2. chlorpheniramine
3. meclizine
4. promethazine
How are the H1 blockers metabolized?
via cytochrome p450 in the liver; don't affect gastric acid secretion or bronchioles
What are 3 typical 2nd generation H1 blockers? How are they metabolized?
1. cetirizine
2. loratadine
3. fexofenadine

Also metabolized via cytochrome p450.
What are 2 H2 blockers and their effects? Side effects?
cimetidine and rantidine, which inhibit basal and histamine induced gastric acid secretion; cimetidine is a potent p450 inhibitor and decreases renal excretion of creatinine
Name 3 ACE inhibitors
1. captopril
2. enalapril
3. lisinopril
Name an angiotensin II receptor antagonist.
1. losarten
What are the 2 main functions of ACE?
1. generate angiotensin II
2. degrade the peptide, bradykinin
What is the rate-limiting step in angiotensin II production?
renin
When is renin secreted?
1. lower BP
2. sympathetic nervous system stimulation
Effects of bradykinin?
release of PGI2 and NO, which reduces vascular resistance; also causes natiuresis and diuresis