cardiovascular pharmacology I Flashcards
(53 cards)
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
