cardiovascular pharmacology I Flashcards
sinus rhythm (normal heart rhythm) is generated by ??? which arise from the SA node
pacemaker impulses
Cardiac cells possess electrical excitability due to ??? which allow the movement of Na+, K+ and Ca2+ across the plasma membrane
voltage-sensitive plasma membrane channels
L-type channels are voltage dependant ??? which play important roles in controlling cardiac rate and rhythm
voltage-dependent Ca2+ channels
Cardiac cells also possess intracellular Ca2+ channels (ryanodine receptors and inositol trisphosphate-activated Ca2+ channels) important in myocardial ???
contraction
dysrhythmia is caused by four basic phenomena:
* Delayed after-depolarisation
* Re-entry
* Ectopic pacemaker activity
* ???
- Heart block
Delayed After-depolarization:
Most commonly due to abnormally raised INTRACELLULAR or EXTRACELLULAR (?) [Ca2+] causing an increase in inward currents and abnormal train of action potentials
intracellular
Delayed after-depolarisation:
Caused less often by hypokalaemia (low extracellular K+) or rarely hypercalcaemia (high extracellular
Ca2+), as a result of drugs targeting ??? in other tissues or other factors
ion channels
??? Describes a situation in which the impulse re- excites regions of cardiac muscle causing continuous circulation of action potentials.
Re-entry
Re-entry results from ??? or anatomical anomalies. Underlies many types of dysrhythmia
myocardial damage
Ectopic pacemaker activity is the result of an excitable group of cells that causes a ??? outside the SA node. This serves as a safety feature but can also cause tachyarrhythmias
premature heartbeat
TRUE or FALSE: Ectopic pacemaker activity serves as a safety feature
TRUE
Ectopic pacemaker activity is often associated with increased ??? activity
sympathetic
Heart block is the result of fibrosis or ischemic damage to the conducting system, often the ??? node. Often treated by implanting an artificial pacemaker
atrioventricular (AV)
Cardiac output is the product of heart rate and mean left ventricular stroke (blood volume ejected per heartbeat) and is controlled by the ??? system
Autonomic Nervous system
Stroke volume is controlled by intrinsic factors (e.g. intracellular Ca2+ and ATP) and extrinsic circulatory factors (e.g. state of arteries and veins, volume and ??? of blood)
viscosity of blood
myocardial contractility depends on intracellular calcium concentrations from ??? and ???
intracellular storage
calcium entry across cell membrane
ventricular function is influence by ??? (cardiac filling pressure) and ??? (peripheral pressure)
preload,
afterload
True or False: the heart is very well perfused and as such is not at greater risk of ischemic damage
FALSE: It is relatively poorly perfused (small blood supply compared to O2 consumption) and thus at greater risk of ischemic damage
Most drugs that effect cardiac heart metabolism, do so by influencing ???
Coronary blood flow
What physiological factors effect coronary blood flow?
- physical factors (narrowing of valves, stenosis)
- Vascular contol of metabolites (adenosine causes vasodialtion)
- Neural + humoral control (autonomic innervation)
Physical Factors Affecting Coronary Blood Flow:
(1) shortening diastole, when heart rate ???
(2) increased ventricular end-diastolic pressure;
(3) reduced diastolic arterial pressure
When heart rate increases;
which receptor is stimulated by noradrenaline or epinephrine?
Adrenoceptors are stimulated by norepinephrine or epinephrine
Cholinergic receptors (muscarinic acetylcholine receptors) are stimulated by ???
acetylcholine
the resting heart is affected by which nervouss systems and what do they do?
- sympathetic NS: mediated mainly via b1 adrenoceptors to increase cyclic AMP formation and Ca2+ channel activity, increasing action potentials
- parasympathetic NS: mediated mainly via muscarinic M2 acetylcholine receptors to reduce cyclic AMP formation and increase K+ channel activity, causing hyperpolarisation
SA node: SNS causes heart rate to INCREASE or DECREASE? PNS does the opposite
increase
Atrial muscle: SNS causes force of contraction to INCREASE or DECREASE? PNS does opposite
INCREASE
AV node: SNS causes automacity to INCREASE or DECREASE? PNS causes opposite effect as well as conduction velocity to decrease
INCREASE
main effects on the heart by sympathetic NS is:
* ??? force of: contraction, heart rate, automaticity (ectopic heart beats – skipped or extra beats; not often a cause of concern)
* Restoration of heart function following cardiac depolarisation
* Reduced cardiac efficiency (increased O2 consumption relative to cardiac work)
* Cardiac hypertrophy (due to stimulation of myocardial a and b adrenoceptors)
Increased
Main effect os PNS on heart are:
* Cardiac slowing
* Decreased ???
* Inhibition of atrioventricular (AV) node conduction
automaticity
Atrial natriuretic peptide (ANP) is released from ??? (cells of the upper heart chambers) in response to ??? (atria stretching) or intravenous saline infusion
atrial cells,
volume overload
B-natriuretic peptide (BNP) is released from ??? cells to oppose ventricular fibrosis and is increased in HF, with pro-BNP used to aid diagnosis of this disease
ventricular muscle
C-natriuretic peptide (CNP) is released from endothelium impacting both heart function and ??? development
bone
TRUE or FALSE: Cardiac natriuretic peptides bind natriuretic peptide receptors to mediate their function
TRUE
ANP and BNP are inactivated by neutral endopeptidase (neprilysin), with the inhibitor ??? used with the angiotensin type I receptor receptor antagonist valsartan in treating chronic heart failure
sacubitril
effects of natriuretic peptides:
* Increase renal Na+ and ??? excretion
* Relax vascular smooth muscle
* Increase vascular permeability
* Inhibit the release or actions of vasoconstrictor or salt-retaining hormones such as aldosterone, angiotensin II, endothelin and antidiuretic hormone
water excretion
Angina occurs when ??? to the myocardium is insufficient for its needs,
resulting in pain to chest, arm and neck
O2 supply
Myocardial infarction occurs when a coronary artery is blocked by a thrombus (atherosclerotic plaque), resulting in death due to mechanical failure or dysrhythmia. what happens to heart tissue to cause this?
Ischaemia of myocardium
Angioplasty is used to open ??? as soon as possible when atherosclerois threatens to cause/ already is causing ischaemia of myocardium
occluded artery
pharmacological therapies for stable type Angina include ??? Statins (to reduce atherosclerosis) Aspirin or other antiplatelet drugs (to prevent thrombosis)
organic nitrates, b-adrenoceptor antagonists, Ca2+ antagonists
pharmacological therapies for unstable type Angina include: ??? (to reduce pain) Aspirin, clopidogrel or other antiplatelet drugs (to prevent
thrombosis)
Organic nitrates
pharmacological therapies for variant type Angina include vasodialters such as ??? and Ca2+ antagonists
organic nitrates
Thrombolytic, antiplatelet drugs (aspirin, clopidogrel), antithrombotic (heparin), are used to open blocked ??? and prevent reocclusion
artery
TRUE or FALSE: O2 is used in myocardial infarctions to relieve ???
arterial hypoxia
organic nitrates promote vasodilation and ???
reduce pain
opioids prevent pain and reduce excessive ??? activity
sympathetic
b-Adrenoceptor antagonists reduce myocardial O2 consumption and demand by lowering the heart rate, blood pressure, myocardial ???
contractility
Angiotensin converting enzyme inhibitors (ACEIs) and angiotensin type I receptor antagonists (ARBs)
are used to treat heart attack to reduce cardiac work and improve cardiac ???
efficiency
drugs that affect ??? directly:
- Autonomic transmitters & related drugs
- Antidysrhythmic drugs / physical means
- Cardiac glycosides & other ionotropic drugs
- Other drugs (e.g. doxorubicin) and hormones (e.g. thyroxine, glucagon)
myocardial cells
drugs that affect vasculature/cardiac function indirectly:
- ??? (e.g. nitrates)
- Heart failure drugs (e.g. diuretics, angiotensin converting enzyme inhibitors)
Anti-anginal drugs
drugs that effect calcium antagonists Affect myocardial cells directly
as well as cardiac function indirectly by relaxing ??? (i.e. verapamil)
smooth muscle
Drugs that Increase Myocardial Contraction:
Cardiac glycosides: ??? is clinically most important. Net effect results in increased intracellular Ca2+ during each action potential
Digoxin
what drug that increases myocardial contraction causes a block of atrioventricular conduction and increased ectopic pacemaker activity (rhythm)
digoxin
Collateral arteries interconnect epicardial coronary arteries and provide an alternative source of
??? to the myocardium in cases of occlusive coronary artery disease
blood supply
