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33 Cards in this Set
- Front
- Back
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What is the hydraulic equation?
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BP is proportional to CO x PVR
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What organs affect blood pressure?
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Heart (output,)
Venules (capacitance,) Arterioles (resistance,) and Kidneys (volume.) Sympathetic innervation regulates these. |
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What factors regulate blood pressure?
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Baroreceptors (autonomic nerves,)
humoral mechanisms (renin-angiotensin-aldosterone,) local hormones (NO dilates, endothelin-1 constricts) |
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How do baroreceptors work?
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Stretch receptors in the carotid artery and aortic arch are activated when blood pressure rises. Sends message to medulla which sends parasympathetic efferents to heart (slow down) and other signals to autonomic ganglia.
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What is the renal response to blood pressure?
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Decreased pressure --> increased renin production --> increased angiotensin II production --> vessel constriction and aldosterone synthesis --> increased salt and water absorption --> increased blood volume
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How do the four classes of antihypertensive drugs work?
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1. Diuretics increase salt excretion, reduce blood volume.
2. Sympathoplegic drugs reduce vascular resistance/inhibit cardiac function/ increase venous pooling. 3. Vasodilators dilate resistance vessels, increase capacitance. 4. Anti-angiotensin drugs reduce peripheral vascular resistance. |
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What salt do diuretics cause clearance of?
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Sodium. Sodium increases vessel stiffness and response to nervous stimulation.
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What diuretic has direct vasodilating effects?
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Indapamide.
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How does amiloride work?
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Amiloride is a diuretic that stimulates sodium excretion and affects calcium movement to decrease smooth muscle contraction.
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How do methyldopa and clonidine work?
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Methyldopa and clonidine depress the sympathetic response and allow parasympathetics to keep going.
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What about autonomic ganglia blocking agents?
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These are not used anymore because of the excessive side effects. Drugs that act at the sympathetic efferents are used instead.
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How do adrenergic neuron blockers work?
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Adrenergic neuron blockers prevent NE from working at the presynaptic neuron.
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How does guanethidine work?
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Guanethidine is an adrenergic neuron blocker. It replaces NE in the storage vesicle and blocks the electrical activity of the channels. Side effects at high doses.
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How does reserpine work?
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Reserpine is an adrenergic neuron blocker. It blocks transport of NE into the storage vesicle. Side effects at high doses.
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How do adrenoreceptor antagonists work?
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Adrenoreceptor antagonists prevent NE from working at the postsynaptic neuron.
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What do beta-adrenergic receptor blockers do?
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Beta-adrenergic receptor blockers decrease heart rate and contractility.
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What are some examples of beta-adrenergic receptor blockers?
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Propranolol, metoprolol, nadolol.
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What do alpha-adrenergic receptor blockers do?
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Alpha-adrenergic receptor blockers block excitation of GCPRs which causes vasodilation.
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What are some examples of alpha-adrenergic receptor blockers?
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Prazosin, terozosin, doxazocin.
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What do vasodilators do?
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Vasodilators relax smooth muscle, which decreases resistance.
Often used in combination with other drugs to elicit compensatory responses of the baroreceptor reflex. |
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What are examples of oral and parenteral vasocilators?
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Oral vasodilators: hydralazine, minoxidil.
Parenteral vasodilators: nitroprusside, diazoxide, fenoldopam. |
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What is the mechanism of hydralazine?
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Mechanism is unclear.
Why did they mention this on a separate slide? The world may never know. |
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What is the mechanism of minoxidil?
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Minoxidil opens smooth muscle K+ channels.
More potassium means hyperpolarization of plasma membrane which makes it more difficult for depolarization (contraction) to happen. Side effects: reflex tachycardia, hirsutism (Rogaine.) |
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What is the mechanism of sodium nitroprusside?
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Sodium nitroprusside is administered parenterally for emergencies. Causes vascular smooth muscle relaxation.
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What is the renin-angiotensin-aldosterone system?
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Renin is released from the adrenal in response to stimuli (reduced pressure.) It is a proteolytic enzyme that cuts angiotensinogen --> angiotensin I --> angiotensin II.
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What is the function of angiotensin II?
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Increase blood pressure.
Cardiac/vascular hypertrophy, systemic vasoconstriction, enhanced sympathetic adrenergic function, increased blood volume, sodium and water retention. |
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What do ACE inhibitors do?
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ACE inhibitors inhibit angiotensin-converting enzyme which blocks angiotensin I from becoming angiotensin II.
Blocks both vasoconstriction and sodium/water retention. |
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What is the other mechanism of ACE inhibitors?
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ACE also inactivates bradykinin, so when ACE is inhibited bradykinin is active. Bradykinin decreases blood pressure through vasodilation.
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What is an example of an ACE inhibitor?
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Captopril. Decreased vascular resistance, sodium/water excretion. No tachycardia.
Side effects: hypotension, renal failure, etc. |
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What do angiotensin II receptor blockers do?
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Angiotensin II receptor blockers inhibit the action of angiotensin II on the two pathways (vasoconstriction and sodium/water retention.)
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How do AT1 receptor blockers work at the muscle synapse?
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AT1 receptor blockers interfere with angiotensin II blocking NE reuptake and interfere with angiotensin II increasing intracellular calcium concentration (vasoconstriction.)
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How do AT1 receptor blockers work at the adrenal cortex?
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AT1 receptors interfere with the IP3/DAG/protein kinase C system to inhibit aldosterone, which normally promotes sodium and water retention.
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What are some examples of ARBs?
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Losartan, Valsartan.
No bradykinin action so more selective than ACE inhibitors, potentially more effective. |
