Heart Questions Flashcards

Questions and Answers

During the period of ventricular filling ________.

blood flows mostly passively through the atria and the open AV valves into the ventricles

If we were able to artificially alter the membrane permeability of pacemaker cells so that sodium influx is more rapid, ________.

threshold is reached more quickly and heart rate would increase

At what point in the cardiac cycle is pressure in the ventricles the highest?

ventricular systole

Why did the changes in BP and HR occur for a patient admitted with chest pains?

To maintain the same cardiac output, the heart rate would need to increase to compensate for a decreased stroke volume. Signup and view all the answers

The second heart sound is heard during which phase of the cardiac cycle?

isovolumetric relaxation Signup and view all the answers

What is the source of ATP for cardiac muscle contraction?

cellular respiration Signup and view all the answers

The role of the coronary arteries is to __________.

supply blood to the heart tissue Signup and view all the answers

How long is the cardiac cycle, assuming the heart beats 75 times per minute?

0.8 seconds Signup and view all the answers

Cardiac tamponade results in ineffective pumping of blood by the heart because the excessive amount of fluid in the pericardial cavity will______.

prevent the heart from filling properly with blood Signup and view all the answers

Which functional feature best describes the manner in which cardiac muscle contracts?

Automaticity (autorhythmicity) promotes the spontaneous contraction of the cardiac muscle cells. Signup and view all the answers

What causes normal heart sounds?

heart valve closure Signup and view all the answers

Which chamber of the heart receives oxygenated blood via the pulmonary circuit?

left atrium Signup and view all the answers

Norepinephrine acts on the heart by ________.

causing threshold to be reached more quickly Signup and view all the answers

The presence of an incompetent tricuspid valve would have the direct effect of causing ______.

reduced efficiency in the delivery of blood to the lungs Signup and view all the answers

Which portion of the electrocardiogram represents the depolarization wave received from the sinoatrial (SA) node through the atria?

P wave Signup and view all the answers

What is the suggested treatment for a patient with an improperly functioning AV node?

Surgery to implant an artificial pacemaker Signup and view all the answers

Damage to the ________ is referred to as heart block.

AV node Signup and view all the answers

Action potentials generated by the autorhythmic cells spread to the contractile cells through what structures in the membrane?

gap junctions Signup and view all the answers

One of the changes that occurs in the pacemaker potential in the SA node is a decreased efflux of what ion?

potassium Signup and view all the answers

When threshold is reached at the SA node, what channels open causing further depolarization of the membrane?

fast calcium Signup and view all the answers

Repolarization of an autorhythmic cell is due to the opening of which channels?

voltage-gated potassium channels Signup and view all the answers

In order to cause cardiac muscle contraction, what causes the depolarization of the contractile cells?

the flow of positive ions from adjacent cells Signup and view all the answers

What is the difference between resting and maximal cardiac output called?

cardiac reserve Signup and view all the answers

What is an abnormally slow heart rate called?

bradycardia Signup and view all the answers

What is heart rate at rest under both autonomic divisions signaling called?

vagal tone Signup and view all the answers

What is an abnormally fast heart rate called?

tachycardia Signup and view all the answers

During contraction of heart muscle cells ________.

some calcium enters the cell from the extracellular space and triggers the release of larger amounts of calcium from intracellular stores Signup and view all the answers

If the vagal nerves to the heart were cut, the result would be that ________.

the heart rate would increase by about 25 beats per minute Signup and view all the answers

Study Notes

Ventricular Filling and Heart Rate

Ventricular filling occurs with passive blood flow from atria through open AV valves into ventricles.
Increasing sodium influx in pacemaker cells leads to quicker threshold attainment, resulting in increased heart rate.

Cardiac Cycle Dynamics

Ventricular systole is when pressures peak in the ventricles, reaching about 120 mm Hg.
Changes in blood pressure and heart rate during hospital admission necessitate increased heart rate to maintain cardiac output due to decreased stroke volume.

Heart Sounds and Cardiac Contraction

The second heart sound is produced during isovolumetric relaxation.
Cardiac muscle contraction is powered by ATP sourced from cellular respiration and functions under automaticity, enabling spontaneous contractions.

Coronary Circulation and Cardiac Cycle Length

Coronary arteries supply oxygenated blood to heart tissue.
A heart rate of 75 beats per minute results in a cardiac cycle duration of 0.8 seconds.

Cardiac Tamponade and Heart Function

Cardiac tamponade inhibits effective blood pumping due to fluid accumulation in the pericardial cavity, preventing proper ventricular filling.

Electrical Activity of the Heart

Normal heart sounds arise from the closure of heart valves.
The left atrium receives oxygenated blood through the pulmonary circuit.

Autonomic Nervous System Influence

Norepinephrine quickens threshold attainment in the heart, enhancing heart rate.
An incompetent tricuspid valve directly reduces blood delivery efficiency to the lungs.

Electrocardiogram and Heart Regulation

The P wave on an electrocardiogram signifies atrial depolarization originating from the SA node.
Suggested treatment for malfunctioning AV node includes the surgical implantation of an artificial pacemaker.

Heart Block and Action Potentials

Damage to the AV node causes heart block, disrupting normal conduction.
Autorhythmic cell action potentials spread to contractile cardiac cells via gap junctions.

Ion Movement in Pacemaker Cells

In SA node cells, decreased potassium efflux contributes to pacemaker potential changes.
Threshold attainment leads to the opening of fast calcium channels, causing additional depolarization.

Cardiac Muscle Contraction Mechanism

Autorhythmic cell repolarization occurs through voltage-gated potassium channels.
Depolarization in contractile cells is initiated by positive ion influx from adjacent cells.

Cardiac Output Capacity

Cardiac reserve represents the difference between resting cardiac output and maximal output.
Bradycardia refers to abnormally slow heart rates, while tachycardia indicates abnormally fast heart rates.

Influences on Heart Rate

Vagal tone describes heart rate at rest influenced by both autonomic divisions.
Cutting vagal nerves to the heart would elevate heart rate by approximately 25 beats per minute.

Calcium Dynamics in Contraction

During cardiac contraction, some calcium enters from extracellular sources, triggering greater calcium release from intracellular stores.

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Description

Test your knowledge on the cardiac cycle and heart physiology with these flashcards. Each card provides key concepts about heart function, including ventricular filling and the role of pacemaker cells. Perfect for students in anatomy or physiology courses.