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23 Cards in this Set
- Front
- Back
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What is the function of the pericardium?
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prevents heart displacement.
Provides a physical barrier from infection, inflammation Contains receptors for pain and that affect BP |
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What effect does the vagus nerve have on the heart?
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Vagus activity causes the release of acetylcholine which decreases heart rate, slows conduction through nodes and can cause vasodilation
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What is the coronary ostia?
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openings in the aorta that supply heart circulation
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What is the function of the pericardium?
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prevents heart displacement.
Provides a physical barrier from infection, inflammation Contains receptors for pain and that affect BP |
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Describe anatomy/location of Purkinje fibers?
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Purkinje Fibers are the terminal branches of the right and left bundle branches, extending from the ventricular apices to the fibrous rings and penetrate the heart wall to the outer myocardium.
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What is atrial natriuretic peptide and what does it do?
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released from heart atrial tissue, a hormone that responds to increased blood volume resulting in increased blood volume and diuretic(Na+ secretion)
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What is the most common receptor in the heart and what does it do?
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Beta 1 receptors. Epi and norepi bind with beta 1 receptors and increase rate of impulse generation, conduction and strength of contraction.(positive inotrope)
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What do Beta 2 receptors do in heart?
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found mostly on coronary arterioles and cause coronary vasodilation when stimulated by epinephrine
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What do Beta 3 receptors do in heart?
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Found in myocardium and coronary vessels. Stimulationso fthese opposes Beta 1 receptor stim and decreases myocardial contractility(neg inotropic effect)
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What are P cells?
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Found in SA and AV nodes(more if SA node), they are the site of impulse formation and have automaticity(depolarize faster than other cardiac cells)
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What is stroke volume?
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the amount(mls) per beat ejected out of left ventricle
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What is cardiac output?
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stroke volume(volume per beat) x heart rate(beats per minute)
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What is pulse pressure?
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systolic BP - Diastolic BP
ex BP 120/80 120-80=40(pulse presssure) |
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What is peripheral vascular resistance?
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The pressure the heart must pump against
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What is preload?
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the pressure generated in the left ventricle at the end of diastole determined by left ventricular end diastolic volume
which is dependent on the amt of venous return to the ventricle, blood left in ventricle after systole. |
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What happens to cardiac output with increased preload?
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It increases
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What is after load?
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the resistance to ejection of blood from the left ventricle
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What effect do catacholamines have on the heart?
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Catacholamines speed up heart rate and shorten the conduction time through the AV node, increasing rhythm of AV pacemaker fibers.
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What does a positive inotrope do? Negative inotrope do?
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Positive inotropes increase contractility and increase cardiac output. Negative inotropes decrease contractility.
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What chemicals are positive or negative inotropes?
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Positive inotropes are epinephrine, norepi. thyroid hormone and dopamine. Negative inotropes are acetylcholine from vagus nerve.
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Which node is known as the pacemaker of the heart? how many action potentials generated per min at rest?
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SA node generates 75 action potentials per min
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If SA node is damaged, how many action potentials will the AV node generate per min?
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AV node will generate 40-60 depolorizations per min.
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What is the refractory period?
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Follows depolarization; no new action potentials can be generated during this time. This period corresponds to the time needed for the opening of channels that permit Na+ and Ca+ influx. Abnormal refractory periods cause dysrhythmias.
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