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36 Cards in this Set

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Describe the mechanisms involved in the physiological control of blood pressure?
The arterioles, the post capillary venules (capacitance vv) and the heart. The kidney contributes to longer term maintenance of blood pressure by regulating the volume of the intravascular fluid.
Smooth muscle tone controlled by mediators secreted by sympathetic nerves and vascular endothelium and by circulating hormones.
two acting effects of beta blockers as vasodilators (indirect acting arterial dilators)
1)cardiac effects: decreases Heart rate and decreases Stroke Volume = decreases Cardiac Output
2) renal effect: blocks the B1-receptors on the juxtaglomerular apparatus, leading to inhibited Renin release therefore preventing actions of angiotensin II (actions = vasoconstrictor, stimulates release of Aldesterone = sodium retention = H20 retention = increased MAP)
What is an example of a Beta Blocker?
Propanolol
What are the side effects of Beta Blockers as vasodilators?
1) cold extremities
2) fadigue (due to reduced cardiac output)
3) bronchoconstriction (B2 receptor agonist effect)

- in the long term, cardiac output returns to normal but results in baroreceptors resetting at a lower level.
What is a positive inotrope?
Increases cardiac contractility, Increases cardiac output
what is a negative inotrope?
Decreases cardiac contractility, Decreases preload
What is a diuretic?
Decreases the preload (volume overload)
What is a vasodilator do for cardiac disease?
Decreases preload, afterload or both
How is an anti-arrythmic useful in cardiac disease?
Increases cardiac output.
How do positive intotropes increase cardiac contractility?
They increase intracellular calcium. They all have potential to cause propblems because they increase cardiac workload.
what are the two most common glycosides?
Digoxin and Digitoxin
How do the glycosides work?
They work by binding to and inhibiting the Na/K ATPase pump on the cardiac myocyte--> increasing intracellular sodium concentraitions--> reducing the exchange of calcium out of the cell for Na. increase in intracellular Ca increases contractility
How does Hydralazine act as an arterial dilator?
True mechanism is unknown thought it works similar to an alpha blocker
How does an alpha blocker work as an arterial dilator?
Acts indirectly as a vasodilator (arterial dilator).
It decreases a-receptor induced vasoconstriction by binding to the a-receptor and prevents Noradrenalin from binding. Without NA binding, dilation occurs.
What the the active effects of Hydralazine as a vasodilator?
1) reduces afterload, therefore reduces regurgitation, therefore promotes forward aortic flow.
2) increases venous oxygen tension
3) decreases pulmonary oedema
Why should you use diuretics with Hydralazine?
it causes hypotension which may stimulate RAAS. RAAS with increase MAP and therefore increase preload and afterload (increase strain on the heart)
What tissues do the L-type calcium channels exist within?
cardiac, vascular smooth muscle, pacemaker tissue.
How do the calcium channel blockers work as vasodilators?
They bind to the inside of the L-type calcium channels and render them inactive. The more active the channel, they more that channel is targeted by the blockers (use dependance)
How do beta blockers effect the heart and vasculature?
1) heart SA and AV nodes - activity is slowed
2) cardiac myocytes - reduce contractility
3) vasculature - dilation of systemic arteries and arterioles
What are the 3 types of calcium channel blockers and what do that have a bigger effect on (cardiac vs vessels)?
1) Verapamil - heart selective
2) Diltiazem - heart and vessel selective
3) Amodipine - vascular selective
What are the roles of cAMP in a cardiac myocyte?
cAMP phosphorylates the Calcium channels so they can open wider when stimulated via action potential (positive inotrope)
What are the roles of cAMP in a vascular smooth muscle?
cAMP inactivates Myosin Light Chain Kinase, therefore inactivating myosin (which relies on an active MLCK for phosphorylation to activate myosin)
What is an example of a commonly used ACE Inhibitor?
Enalapril
What is an example of a commonly used Angiotensin II Receptor Blocker?
Losartan
What are three roles propranolol (a common Beta blocker) can be used for?
- negative inotrope
- vasodilator (for hypertension)
- anti arythmic
What class of drugs can be used as anti-arrythmics?
negative inotropes

- the sodium channel blocker Quinidine can also be used
How do calculate pulse pressure?
systolic pressure - diastolic pressure = Pulse Pressure
How do you calculate Mean Arterial Pressure?
Diastolic pressure + 1/3 pulse pressure = MAP
How do you calculate Cardiac Output?
Stroke Volume (ml) x Heart rate (beats per min)
How do you calculate Stroke Volume?
End Diastolic volume-end systolic
How do you calculate ejection fraction?
Stroke Volume / end diastolic volume
Which muscle cell contains troponin?
Cardiac muscle
Which muscle contains calmodulin?
Vascular smooth muscle
WHich cell has a better developed sarcoplasmic reticulum (between cardiac and smooth muscle cells)?
cardiac myocyte cell
Which cells have t-tubules (cardiac vs smooth muscle)?
cardiac
Why are smooth muscles able to contain a basal tone?
Smooth muscle stimulation results in a maintained isometric force, but contractions are extremly slow. Smooth muscle cells maintain large forces almost continually at extremely low energy costs. Thus there is a basal degree of vascular smooth muscle contraction. Spontaneous depolarisation leads to action potentials that produce this basal tone.