Cardiac Physiology Quiz
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Questions and Answers

What is referred to as systolic pressure?

  • Pressure in the arteries after the ventricles contract (correct)
  • Pressure during the filling of the atria
  • Pressure generated during the relaxation of the ventricles
  • Pressure generated by the atrial contraction

Which valve prevents backflow of blood into the right atrium during ventricular contraction?

  • Mitral valve
  • Aortic valve
  • Tricuspid valve (correct)
  • Pulmonary valve

During which phase does blood fill the ventricles?

  • Ventricular emptying
  • Systole
  • Diastole (correct)
  • Atrial contraction

Which structure initiates the electrical signal for heart contractions?

<p>SA node (B)</p> Signup and view all the answers

What type of blood pressure is measured when the ventricles are relaxed?

<p>Diastolic pressure (B)</p> Signup and view all the answers

What is the primary purpose of ventricular contraction during systole?

<p>To pump blood to the body and lungs (D)</p> Signup and view all the answers

Which of the following statements is true regarding the pressures in the ventricles?

<p>The left ventricle generates higher pressure than the right ventricle. (A)</p> Signup and view all the answers

What mechanism ensures one-directional flow of blood through the heart?

<p>Opening and closing of heart valves (D)</p> Signup and view all the answers

What is the primary function of the sinoatrial (SA) node in the cardiac conduction system?

<p>To generate the depolarization wave that triggers atrial contraction (D)</p> Signup and view all the answers

Which structure is responsible for transmitting impulses six times faster than normal cell-to-cell connections?

<p>Bachmann's bundle (A)</p> Signup and view all the answers

What characteristic of the atrioventricular (AV) node contributes to the delay in impulse transmission to the ventricles?

<p>Weak transmission of the depolarization wave (C)</p> Signup and view all the answers

Where is the bundle of His located in relation to the atrioventricular node?

<p>Immediately below the AV node in the interventricular septum (A)</p> Signup and view all the answers

Which substance is primarily responsible for vasodilation and can form anywhere in the circulatory system?

<p>Bradykinin (D)</p> Signup and view all the answers

What is the effect of increased extracellular Ca2+ on the heart?

<p>Increases the force of contraction (A)</p> Signup and view all the answers

What is the typical duration of normal P-waves in an electrocardiogram?

<p>0.06 to 0.11 seconds (C)</p> Signup and view all the answers

How do the right and left bundle branches function after the impulse leaves the bundle of His?

<p>They transmit electrical impulses to the left and right ventricles, respectively (A)</p> Signup and view all the answers

Which hormone acts as a potent vasoconstrictor and also regulates fluid volume by controlling water reabsorption?

<p>Vasopressin (A)</p> Signup and view all the answers

What is the significance of the relatively weak transmission of the depolarization wave through the AV node?

<p>It prevents rapid contraction of the ventricles before atrial contraction (A)</p> Signup and view all the answers

How do chemoreceptors in the brain and carotids respond to decreased O2 levels?

<p>Increase sympathetic stimulation (C)</p> Signup and view all the answers

What aspect of the SA node's depolarization is noteworthy in electrocardiography?

<p>It is too weak to be recorded by the electrocardiograph (B)</p> Signup and view all the answers

Which of the following substances is NOT a vasodilating agent?

<p>Epinephrine (B)</p> Signup and view all the answers

What is the primary function of angiotensin in the body?

<p>Vasoconstriction (B)</p> Signup and view all the answers

Which chemical would likely cause local edema due to increased capillary permeability?

<p>Histamine (A)</p> Signup and view all the answers

A decrease in arterial pressure triggers which of the following responses?

<p>Release of renin from kidneys (B)</p> Signup and view all the answers

What mechanism allows the cardiac conduction cells to respond to an electrochemical stimulus?

<p>Changes in membrane permeability to ions (A)</p> Signup and view all the answers

During which phase of the cardiac cycle does blood begin to flow out of the ventricles?

<p>Ejection phase (D)</p> Signup and view all the answers

What is the role of the Sinoatrial (SA) node in the heart?

<p>It serves as the heart's natural pacemaker (C)</p> Signup and view all the answers

What is the approximate change in membrane potential required for an action potential in ventricular muscle?

<p>110 mV (D)</p> Signup and view all the answers

Which node receives the electrical impulse after it is generated by the SA node?

<p>Atrioventricular (AV) node (A)</p> Signup and view all the answers

What happens to the pressure in the ventricles during early diastole?

<p>It drops to zero (D)</p> Signup and view all the answers

Which ions primarily flow into the cardiac conduction cells during electrochemical stimulation?

<p>Sodium, potassium, and calcium ions (D)</p> Signup and view all the answers

What initiates the contraction of the cardiac muscle tissue?

<p>Electrical impulses triggered by the SA node (D)</p> Signup and view all the answers

What does a prolonged P-R interval indicate?

<p>Delayed conduction from the sinoatrial node to the atrioventricular node (A)</p> Signup and view all the answers

Which of the following describes the QRS complex?

<p>Indicates the spread of electrical impulses through the ventricles (A)</p> Signup and view all the answers

How is stroke volume calculated?

<p>End diastolic volume minus end systolic volume (B)</p> Signup and view all the answers

What is the normal duration of a QRS complex?

<p>0.10 seconds (B)</p> Signup and view all the answers

What does the S-T segment represent?

<p>No electrical activity with ventricular contraction (B)</p> Signup and view all the answers

Which of the following factors does not decrease cardiac output?

<p>Increased stroke volume (C)</p> Signup and view all the answers

What percentage of blood volume is typically ejected from a healthy heart during contraction?

<p>60% (A)</p> Signup and view all the answers

What is the average cardiac output for a resting person?

<p>5000 ml/min (B)</p> Signup and view all the answers

What is the correct formula used to calculate cardiac output?

<p>Cardiac Output = Stroke Volume x Heart Rate (D)</p> Signup and view all the answers

Under sympathetic control, which effect is NOT observed on the heart?

<p>Decreased force of contraction (B)</p> Signup and view all the answers

Which of the following statements regarding parasympathetic control is accurate?

<p>It can lower heart rate to 20-30 bpm. (A)</p> Signup and view all the answers

What determines the stroke volume of the heart?

<p>End diastolic volume minus end systolic volume (A)</p> Signup and view all the answers

Which factor is NOT listed as an extrinsic regulator of the heart?

<p>Physical exercise (C)</p> Signup and view all the answers

What is the primary neurotransmitter released by most postsynaptic sympathetic nerve endings?

<p>Norepinephrine (A)</p> Signup and view all the answers

What is the expected stroke volume for a resting college student with a cardiac output of 5 L/min and a heart rate of 72 beats/min?

<p>Approximately 70 mL/beat (A)</p> Signup and view all the answers

Which condition correlates with sympathetic stimulation in terms of blood flow?

<p>Increased resistance leading to altered blood flow (B)</p> Signup and view all the answers

Flashcards

Ventricular Systole

The contraction phase of the ventricles, where blood is pushed out of the heart.

Ventricular Diastole

The relaxation phase of the ventricles, where blood flows into the chambers.

SA Node

The heart's natural pacemaker, responsible for initiating the heartbeat.

Tricuspid and Mitral Valves

The valves between the atria and ventricles, preventing backflow during ventricular contraction.

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Pulmonary and Aortic Valves

The valves between the ventricles and the arteries, preventing backflow during ventricular relaxation.

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Pulmonary Arterial Pressure

The pressure generated by the right ventricle during systole, responsible for pushing blood to the lungs.

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Aortic Pressure

The pressure generated by the left ventricle during systole, responsible for pushing blood to the body.

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Heartbeat

The rhythmic series of contractions and relaxations of the heart chambers, responsible for pumping blood.

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Isometric Contraction

The phase of the cardiac cycle when the ventricles contract, increasing pressure within the ventricles but without blood being ejected.

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Ejection

The phase of the cardiac cycle when blood is actively pumped out of the ventricles.

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Excitability

The ability of muscle cells to respond to an electrochemical stimulus.

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Cardiac Conduction Cells

The specialized cells that initiate and conduct electrical impulses throughout the heart, controlling the heart's rhythm.

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Sinoatrial Node (SA Node)

A location in the upper right atrium that acts as the heart's natural pacemaker, initiating the electrical impulse for each heartbeat.

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Atrioventricular Node (AV Node)

A location in the lower right atrium that receives the electrical impulse from the SA node and transmits it to the ventricles.

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Bundle Branches

The specialized nerve fibers that transmit the electrical impulse from the AV node to the ventricles, causing them to contract.

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Myocardium

The tissue that forms the walls of the heart chambers, responsible for contracting and pumping blood.

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Sinoatrial (SA) node

Specialized group of cells in the right atrium responsible for initiating the heart's electrical activity.

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Internodal and Interatrial pathways

Specialized pathways in the atria that rapidly conduct the electrical impulse from the SA node.

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Atrioventricular (AV) node

Specialized cluster of cells in the heart that acts as a bridge between the atria and ventricles, delaying the electrical impulse.

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Bundle of His

A bundle of specialized fibers that carries the electrical impulse from the AV node to the ventricles.

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Right and left bundle branches

Branches of the bundle of His that conduct the electrical impulse to the right and left ventricles.

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P-wave

The first wave on an electrocardiogram (ECG) representing atrial depolarization.

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Atrial contraction

The part of the P-wave that is associated with atrial contraction, occurs shortly after the P-wave begins.

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Duration of the P-wave

The normal duration of the P-wave on an ECG.

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P-R interval

The time it takes for electricity to travel from the sinoatrial (SA) node to the atrioventricular (AV) node, encompassing atrial depolarization.

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Humoral Regulation of Circulation

The regulation of blood flow through the body by substances present in the bloodstream.

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Vasoconstrictor

A substance that narrows blood vessels, increasing blood pressure.

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QRS complex

The electrical activity reflecting ventricular depolarization, signaling the spread of the electrical impulse through the ventricles, leading to their contraction.

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Epinephrine and Norepinephrine

Hormones secreted by the adrenal medulla that constrict blood vessels.

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Angiotensin

A powerful vasoconstrictor formed by the kidneys in response to low blood pressure.

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S-T segment

The interval on an ECG representing the time when ventricles are actively contracting but no electrical activity is occurring.

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Vasodilator

A substance that widens blood vessels, decreasing blood pressure.

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Bradykinin

A powerful vasodilator formed in the circulatory system that increases capillary permeability.

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Stroke volume

The amount of blood ejected from the left ventricle with each heartbeat, directly related to the force of ventricular contraction.

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Serotonin

A chemical found in various tissues that can either dilate or constrict blood vessels depending on the circumstances.

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Cardiac output

The amount of blood pumped by each ventricle per minute, influenced by factors like heart rate and blood volume.

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Histamine

A potent vasodilator released by mast cells and involved in allergic reactions.

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Stroke volume (alternate definition)

The difference between the amount of blood in a ventricle at the end of diastole (EDV) and the amount of blood remaining after contraction (ESV).

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Heart Rate

The number of times the heart beats per minute.

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Cardiac Output Formula

Cardiac Output is the product of Stroke Volume multiplied by Heart Rate.

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Sympathetic Control of Heart

The sympathetic nervous system increases heart rate and force of contraction.

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Sympathetic Control of Blood Vessels

The sympathetic nervous system can increase resistance in blood vessels, leading to increased blood pressure.

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Parasympathetic Control of Heart

The parasympathetic nervous system decreases heart rate and force of contraction.

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Parasympathetic Origin

The parasympathetic nervous system originates in the medulla of the brain and branches to the heart and digestive organs.

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Study Notes

Cardiac Physiology

  • The heart's pumping action involves two phases: systole and diastole.
  • Systole is the contraction of the ventricles, forcing blood into the arteries. Systolic pressure is the increased pressure during this contraction.
  • Diastole is the relaxation of the ventricles, allowing them to fill with blood from the atria. Diastolic pressure is the lower pressure during relaxation.
  • Heartbeat is a two-part process. The first part, diastole, involves the filling of the atria and ventricles with blood.
  • The second part of the heartbeat is systole. It involves the contraction of the ventricles, forcing blood out into the lungs and body.

Normal Cardiovascular Pressures

  • Various locations in the cardiovascular system have different pressure levels.
  • These pressures—measured in mmHg—vary based on the specific location and normal ranges.
  • See the table in the supplemental material for a detailed breakdown.

Cardiac Conduction System

  • Electrical impulses originating at the Sinoatrial (SA) node initiate cardiac contraction.
  • The SA node is the natural pacemaker, located in the upper wall of the right atrium.
  • The electrical signal moves through the atria to stimulate contraction.
  • Then, the signal passes to the Atrioventricular (AV) node.
  • Next, the signal goes down the bundle of His, causing the ventricles to contract.
  • The signal then branches into the right and left bundle branches.
  • Special pathways or bundles, called interatrial pathways and internodal pathways, expedite the movement of the electrical signal through the conduction system.

Electrocardiography (ECG/EKG)

  • ECG measures the electrical activity of the heart over time.
  • Specific waveforms or segments on the ECG, such as the P wave, P-R interval, QRS complex, and T wave each represent different stages of the cardiac cycle.
  • Different parts of the electrocardiogram correspond to atrial and ventricular depolarization and repolarization.
  • See the included images for examples of these traces.

Stroke Volume

  • The stroke volume is the amount of blood ejected from the heart during each beat (systole)
  • Stroke volume is calculated as the difference between the end-diastolic volume (EDV) and the end-systolic volume (ESV).
  • Stroke volume is directly linked to ventricular contraction force and plays a prominent role in determining cardiac output.

Cardiac Output

  • Cardiac output (CO) is the amount of blood pumped by the heart per minute.
  • Cardiac output is calculated by multiplying stroke volume by the heart rate.
  • Both resting and exercising cardiac output values are provided.
  • Normal cardiac output varies depending on an individual's exertion level.

Extrinsic Regulation of the Heart

  • The heart is regulated by both neural (nervous) and humoral (chemical) factors.
  • Sympathetic nervous system stimulation increases heart rate, force of contraction, and therefore cardiac output, associated with the "fight-or-flight" response.
  • Parasympathetic nervous system stimulation (vagus nerve) reduces heart rate and force of contraction.
  • Blood pressure, body temperature and other factors all affect heart rate in extrinsic control pathways.

Humoral Regulation of Circulation

  • Chemical substances in the bloodstream regulate blood circulation.
  • Vasoconstricting agents, like epinephrine and norepinephrine, and angiotensin, constrict blood vessels.
  • Vasodilating agents, like bradykinin, histamine, and others, widen blood vessels.
  • These humoral factors affect blood flow, pressure and other aspects of circulation.

Effect of Specific Factors on Heart Rate/Contraction

  • Chemoreceptors and other systems monitor various factors like pH, CO2, and oxygen in the blood.
  • Ion concentrations (K+ and Ca2+) influence heart rate and contractility.
  • Blood pressure is monitored by baroreceptors.
  • Body temperature alters heart rate.

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Related Documents

Cardiac Physiology PDF

Description

Test your knowledge on cardiac physiology, including the heart's pumping action, phases of heartbeat, and normal cardiovascular pressures. This quiz covers key concepts such as systole, diastole, and the cardiac conduction system.

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