Cardiac Physiology Overview
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Questions and Answers

What is the equation used to calculate cardiac output?

  • Cardiac Output = Stroke Volume x Heart Rate (correct)
  • Cardiac Output = Stroke Volume / Heart Rate
  • Cardiac Output = Stroke Volume - Heart Rate
  • Cardiac Output = Stroke Volume + Heart Rate

What is the average stroke volume per beat?

  • 70 ml/beat (correct)
  • 90 ml/beat
  • 50 ml/beat
  • 100 ml/beat

Which valves are classified as atrioventricular valves?

  • Mitral and Tricuspid (correct)
  • Aortic and Pulmonic
  • Left and Right Semilunar
  • Ventricular and Atrial

During which phase do semilunar valves open?

<p>When the ventricles contract (D)</p> Signup and view all the answers

What role do pacemaker cells play in the heart?

<p>They set the basal heart rate (B)</p> Signup and view all the answers

What effect do motor neurons from the Sympathetic and Parasympathetic nervous system have on the heart?

<p>They modify the basal rate of pacemaker depolarization (D)</p> Signup and view all the answers

What can the cardiac output increase to during exercise?

<p>20 to 25 L/min (B)</p> Signup and view all the answers

What is the primary function of the gap junctions in cardiac muscle cells?

<p>To couple muscle cells electrically (A)</p> Signup and view all the answers

What primarily drives the net movement of K+ out of the cell during the repolarization plateau?

<p>Both concentration and electrical gradients (C)</p> Signup and view all the answers

What happens to voltage-gated Ca2+ channels during final repolarization (phase 3)?

<p>They inactivate spontaneously (D)</p> Signup and view all the answers

During which phase do voltage-gated Na+, K+, and Ca2+ channels close?

<p>Phase 4 (B)</p> Signup and view all the answers

What is the result of the inactivation of voltage-gated Ca2+ channels in phase 3?

<p>Increased K+ permeability (C)</p> Signup and view all the answers

How does the net cation efflux via K+ compare to the net cation influx via Ca2+ during the repolarization plateau?

<p>They are approximately equal (B)</p> Signup and view all the answers

What primarily stimulates the opening of voltage-gated Ca2+ channels in the cardiac action potential?

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

What effect does the blockage of K+ leak channels have during repolarization phases?

<p>Decreases K+ efflux (B)</p> Signup and view all the answers

Why does the electrical gradient influence cation movement during phase 2?

<p>Because movement into the cell occurs when the membrane potential is negative (B)</p> Signup and view all the answers

What occurs immediately after the closure of the AV valves during the cardiac cycle?

<p>Opening of the SL valves (C)</p> Signup and view all the answers

Which heart sound is associated with the closing of the AV valves?

<p>S1 (D)</p> Signup and view all the answers

During diastole, what is the relationship between left ventricular pressure and left atrial pressure?

<p>Left ventricular pressure is lower than left atrial pressure (D)</p> Signup and view all the answers

What phase follows the depolarization of the atrium indicated by the P wave?

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

What occurs during isovolumetric contraction?

<p>AV valves are closed (A)</p> Signup and view all the answers

What happens during the relaxation of cardiac muscle in the cardiac cycle?

<p>Decrease in ventricular chamber pressure (B)</p> Signup and view all the answers

Which of the following indicates the beginning of systole?

<p>Closing of the AV valves (C)</p> Signup and view all the answers

What marks the end of systole in the cardiac cycle?

<p>Closing of the SL valves (B)</p> Signup and view all the answers

What is the primary function of the atrial volume receptor reflex?

<p>Regulation of blood volume (B)</p> Signup and view all the answers

In response to decreased blood volume, how does the atrial volume receptor reflex affect renin release?

<p>It decreases renal excretion of Na+/H2O. (C)</p> Signup and view all the answers

Which of the following best describes what an electrocardiogram (ECG) measures?

<p>The electrical activity of the heart (A)</p> Signup and view all the answers

How are ECG leads arranged to provide standard comparisons in heart activity recordings?

<p>A mix of limb and chest connections (C)</p> Signup and view all the answers

What is the main reason for using the same 12 leads in all ECG recordings?

<p>To identify deviations from normal (A)</p> Signup and view all the answers

What role do baroreceptors play in blood pressure regulation?

<p>They sense changes in vessel stretch and send signals to the CNS. (D)</p> Signup and view all the answers

How does the CNS respond to changes in blood pressure detected by baroreceptors?

<p>It inhibits sympathetic signaling and stimulates parasympathetic signaling. (A)</p> Signup and view all the answers

What is the primary function of the baroreceptor reflex?

<p>To minimize fluctuations in blood pressure. (A)</p> Signup and view all the answers

What is the speed of the baroreceptor reflex in regulating blood pressure?

<p>It reacts instantly, within seconds. (B)</p> Signup and view all the answers

How does the baroreceptor reflex adapt to long-term changes in blood pressure?

<p>It adjusts the normal blood pressure set point to a new level. (A)</p> Signup and view all the answers

What is the average systolic blood pressure in mmHg?

<p>120 mmHg (D)</p> Signup and view all the answers

How is pulse pressure calculated?

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

What is the formula for Mean Arterial Pressure (MAP)?

<p>Diastolic pressure + 1/3 pulse pressure (D)</p> Signup and view all the answers

Which vessel type has the greatest total cross-sectional area?

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

What happens to blood flow velocity as total cross-sectional area increases?

<p>It decreases. (A)</p> Signup and view all the answers

Which variable has the largest impact on vascular resistance?

<p>Radius of the vessel (A)</p> Signup and view all the answers

If the radius of one tube is twice that of another tube, how does their resistance compare?

<p>The smaller tube has 16-times greater resistance. (B)</p> Signup and view all the answers

In systemic circulation, what kind of pressure and resistance is typical?

<p>High-pressure, high-resistance (C)</p> Signup and view all the answers

Which of the following correctly describes the relationship between surface area and diffusion efficiency?

<p>Higher surface area increases diffusion efficiency. (A)</p> Signup and view all the answers

Flashcards

Repolarization plateau (phase 2)

The period where the membrane potential remains relatively stable due to the balance between potassium outflow and calcium inflow.

Final Repolarization (phase 3)

The influx of potassium ions due to continued openness of voltage-gated potassium channels dominates the situation and drives the membrane potential back to resting values.

Resting membrane potential (phase 4)

The period where the membrane potential is stable due to the closure of all voltage-gated channels and the restoration of ionic gradients to their resting levels.

Repolarization

The process of membrane potential returning to its initial resting state, following a depolarizing event, effectively recharging the cell for another action potential.

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Ionic Currents

The movement of ions across the cell membrane which alters the membrane potential.

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Membrane Permeability

The change in membrane permeability that occurs in response to the opening and closing of ion channels, which ultimately dictates the direction and magnitude of ionic currents.

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Electrochemical Gradient

The driving force behind the movement of ions across the membrane, determined by the difference in concentration and charge on either side of the membrane.

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Threshold potential

The minimum amount of stimulation required to trigger an action potential.

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Stroke Volume (SV)

The volume of blood pumped out of the left ventricle with each heartbeat.

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Heart Rate (HR)

The number of times the heart beats per minute.

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Cardiac Output (CO)

The amount of blood pumped by the heart per minute. It's calculated by multiplying Stroke Volume (SV) by Heart Rate (HR).

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Atrioventricular Valves

The valves between the atria and ventricles of the heart. They open during atrial contraction to allow blood to flow into the ventricles and close during ventricular contraction to prevent backflow.

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Semilunar Valves

The valves between the ventricles and the aorta and pulmonary artery. They open during ventricular contraction to allow blood to flow out of the heart and close during ventricular relaxation to prevent backflow.

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Sinoatrial (SA) Node

A group of specialized cells in the right atrium that initiate heartbeats. They spontaneously depolarize, generating an electrical signal that spreads throughout the heart.

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Gap Junctions

The junction between cardiac muscle cells that allow electrical signals to pass quickly and efficiently.

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Pacemaker Activity

The ability of the SA node to generate an electrical signal without input from the nervous system. It determines the heart's resting or 'basal' rate.

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Fast Response Action Potential (Depolarization Phase)

A rapid phase of polarization during which the cell membrane potential changes from a negative to a positive value.

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Diastole

The period when the heart muscle relaxes and refills with blood. The heart chambers are expanding.

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Systole

The period when the heart muscle contracts and pumps blood out of the heart chambers.

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S1 Heart Sound

The first heart sound, often described as a 'lub', produced by the closure of the AV valves, which separate the atria and ventricles.

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S2 Heart Sound

The second heart sound, often described as a 'dub', produced by the closure of the semilunar valves, which separate the ventricles from the aorta and pulmonary artery.

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Isovolumetric Contraction

The period during ventricular contraction where the heart chamber volume remains the same before ejection.

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Cardiac Muscle Contraction (A)

The contraction of the cardiac muscle, characterized by an increase in chamber pressure and the opening of the semilunar valves.

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Cardiac Muscle Contraction (B)

The relaxation of the cardiac muscle leading to a decrease in chamber pressure and the opening of the AV valves.

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Baroreceptors

Specialized sensory receptors located in the walls of the aortic arch and carotid sinus that detect changes in blood pressure.

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Baroreceptor reflex

A reflex that helps regulate blood pressure by adjusting heart rate and blood vessel diameter. It's triggered by changes in blood pressure detected by baroreceptors.

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CNS role in baroreceptor reflex

The baroreceptor reflex sends signals to the brain, which then instructs both the sympathetic and parasympathetic nervous systems to adjust heart rate and blood vessel diameter. This helps to stabilize blood pressure.

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Speed and adaption of baroreceptor reflex

The baroreceptor reflex is very rapid, responding within a second to changes in blood pressure. However, it can adapt to long-term changes in blood pressure, such as those associated with hypertension.

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Baroreceptor reflex and blood loss

A rapid drop in blood pressure, such as that caused by blood loss, is partially mitigated by the baroreceptor reflex, which limits the decline in pressure.

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What is the Baroreceptor Reflex?

The Baroreceptor Reflex detects changes in blood pressure, triggering adjustments in heart rate and blood vessel constriction to maintain a stable blood pressure.

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What is the AVR Reflex?

The Atrial Volume Receptor (AVR) Reflex regulates blood volume by adjusting the release of renin, an enzyme that activates the renin-angiotensin-aldosterone-system (RAAS). RAAS regulates sodium and water balance.

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Explain the RAAS.

The renin-angiotensin-aldosterone system (RAAS) is a hormonal pathway that regulates blood pressure and blood volume.

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What is an ECG?

An electrocardiogram (ECG) is a recording of the electrical activity of the heart, visualized as a tracing on a monitor.

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What are ECG Leads?

ECG leads provide different views of the heart's electrical activity. 12-Lead ECG records electrical activity from various locations, including the limbs and chest, providing a comprehensive view of the heart's function.

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Systolic Pressure

The maximum pressure in the arteries during ventricular contraction (systole).

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Diastolic Pressure

The minimum pressure in the arteries during ventricular relaxation (diastole).

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Pulse Pressure

The difference between systolic and diastolic pressure, reflecting the force of blood ejected with each heartbeat.

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Mean Arterial Pressure (MAP)

The average pressure in the arteries, responsible for driving blood forward.

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Systemic Circulation

High-pressure circulation that transports blood from the heart to the body.

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Pulmonary Circulation

Low-pressure circulation that transports blood from the heart to the lungs and back.

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Vascular Resistance

The opposition to blood flow through a vessel, determined by factors like vessel diameter and blood viscosity.

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Total Cross Sectional Area

The total surface area of all blood vessels in a particular section of the circulatory system.

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Blood Flow Velocity

The speed at which blood flows through a vessel, which decreases as the total cross-sectional area increases.

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Poiseuille's Law

The relationship between the blood flow, the pressure difference driving the flow, and the resistance to flow. It states that flow is proportional to pressure difference and inversely proportional to resistance.

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Study Notes

Physiology (0603302)

  • Course: Cardiac Physiology
  • Semester: Summer 2023/2024
  • Instructor: Dr. Mohammad A. Abedal-Majed
  • Institution: The University of Jordan, School of Agriculture

Cardiac Cycle

  • Contraction of cardiac muscle:

    • Increased ventricular chamber pressure
    • Closing of AV (inlet) valves
    • Opening of SL (outlet) valves

  • Relaxation of cardiac muscle:

    • Decreased ventricular chamber pressure
    • Closing of SL(outlet) valves
    • Opening of AV (inlet) valves

Blood Flow

  • Pulmonary Circulation (short):

    • Poorly oxygenated blood to lungs
    • Right ventricle → pulmonary artery → pulmonary vessels
    • Delivery of highly oxygenated blood to the heart
    • Pulmonary vessels → pulmonary vein

  • Systemic Circulation (high pressure):

    • Highly oxygenated blood to tissues
    • Left ventricle → aorta → systemic vessels
    • Delivery of poorly oxygenated blood to the heart
    • Systemic vessels → vena cava → R atrium

Vascular System

  • Functional components:

    • Pump (heart)
    • Distributing tubes (arterial system)
    • Collecting tubes (venous system)
    • Exchange system (capillary beds)

  • Distributing (arterial system):

    • Branching of aorta & pulmonary artery
    • Progressively smaller vessels (arteries → arterioles → capillaries)

  • Collecting (venous system):

    • Empty into vena cava & pulmonary vein
    • Joining of smaller vessels (venules → veins)
    • Back to the heart via vena cava

  • Exchange (capillary beds):

    • Oxygen, glucose, and nutrients pass from blood to cells
    • Carbon dioxide, and waste products pass from cells to blood

Cardiac Action Potentials

  • Fast response action potential:

    • Rapid depolarization phase
    • Influx of Na+ ions
    • Brief repolarization

  • Slow response action potential:

    • Repolarization plateau phase
    • Influx of Ca2+ ions
    • Depolarization caused by Ca2+ influx

Cardiac Valves

  • Atrioventricular valves: Control blood flow between atria and ventricles

    • Left: mitral valve
    • Right: tricuspid valve
    • Open during atrial contraction, close during ventricular contraction

  • Semilunar valves: Control blood flow from ventricles into arteries

    • Left: aortic valve
    • Right: pulmonic valve
    • Open during ventricular contraction, close during ventricular relaxation

Heart Valves

  • Atrioventricular (AV): control blood flow between atria and ventricles
    • Mitral (Left)
    • Tricuspid (Right)
  • Semilunar: control blood exiting ventricles
    • Aortic (Left)
    • Pulmonary (Right)

Cardiac Cycle

  • A contraction phase (systole) and a relaxation phase (diastole).

Blood Pressure

  • Regulation:
    • Sympathetic nervous system (↑ heart rate, ↑ contractility, ↑ vasoconstriction) -Parasympathetic nervous system (↓ heart rate,↓ contractility, ↓ vasoconstriction)
  • Blood pressure measurements
    • First sound-AV valves close
    • Second sound-Semilunar valves close.
  • Vascular Resistance and Blood pressure: Pressure driven blood flow, Resistance is inversely correlated with radius(smaller radius = greater resistance).

Baroreceptors and Volume Reflexes

  • Baroreceptor reflex: Detecting changes in blood pressure
    • Afferent signals from baroreceptors to the CNS
    • CNS then modulates sympathetic and parasympathetic activity to return blood pressure to normal
  • Atrial volume receptor reflex: Detecting changes in blood volume
    • Detecting changes in atrial stretch
    • CNS then modulates sympathetic and parasympathetic activity to maintain blood volume
    • Role of renin-angiotensin-aldosterone system (RAAS)

Clinical Applications

  • ECG: Graphical tracing of cardiac electrical potentials. Uses 12 leads to record data from various locations on the body. Used clinically to detect heart disease.
  • Blood viscosity: Blood becomes more viscous in cases of polycythemia, and less viscous in anemia.
  • Blood pressure measurements: Detecting blood pressure changes in arteries via Korotkoff sounds.

Additional Information (Not fully organized):

  • Cardiac output = stroke volume x heart rate (CO = SV * HR)
  • Resting CO = ~5 Liters/min, Exercising CO = 20 - 25 Liters/min
  • Various components of heart, lungs, and vascular system are associated with blood flow and pressure regulation
  • Multiple diagrams describe circulation, blood flow, and pressure differences from the heart, and through large and small blood vessels such as arteries, arterioles, capillaries, venules, and veins throughout the body.

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Ch.3 Cardiac Physiology Summer 2023/2024 PDF

Description

This quiz covers essential concepts of cardiac physiology, including cardiac output, stroke volume, and the roles of heart valves and pacemaker cells. Test your knowledge on how the nervous system influences heart function and the mechanics of cardiac muscle cells. Perfect for students of human physiology or medical professionals seeking to refresh their understanding.

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