Cardiovascular System Overview
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Questions and Answers

What is the pressure in the pulmonary artery during systole?

  • About 50 mmHg
  • About 25 mmHg (correct)
  • About 35 mmHg
  • About 20 mmHg

Which of the following statements is true about baroreceptors?

  • They are sensitive to changes in arterial pressure (correct)
  • They are only found in the carotid arteries
  • They normally fire during early diastole
  • They send impulses through the vagus nerve

Where is the best site to measure mixed venous PO2?

  • Pulmonary Vein
  • Right Atrium
  • Superior Vena Cava
  • Pulmonary Artery (correct)

What percentage of ventricular filling is contributed by atrial contraction?

<p>30% (B)</p> Signup and view all the answers

What is the lowest intrinsic discharge activity among cardiac conduction tissues?

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

With a mixed venous oxygen content of 110 ml/L and an arterial oxygen content of 150 ml/L and an oxygen uptake of 280 ml/min, what is the cardiac output?

<p>7 liters/min (C)</p> Signup and view all the answers

Where is the greatest volume of blood found in the body?

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

What pressure in the right ventricle is approximately when the pulmonary valve closes?

<p>30 mmHg (B)</p> Signup and view all the answers

What primarily causes the long refractory period in cardiac muscle?

<p>Of Ca2+ influx (C)</p> Signup and view all the answers

What is the primary advantage of the Starling mechanism in the heart?

<p>Ensure that the ventricles operate at an optimum length (C)</p> Signup and view all the answers

What is the result of baroreceptor stimulation?

<p>Decreased arterial blood pressure (B)</p> Signup and view all the answers

An increase in arterial pulse pressure is likely to be associated with which of the following?

<p>An increased peripheral resistance (A)</p> Signup and view all the answers

The fourth heart sound is associated with which event in the cardiac cycle?

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

Frank Starling's law of the heart explains which phenomenon?

<p>Increased stroke volume when end-diastolic volume is increased (C)</p> Signup and view all the answers

A decrease in carotid sinus pressure would lead to what change in cardiac output?

<p>Decrease in cardiac output (D)</p> Signup and view all the answers

What does the QRS wave in the ECG represent?

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

Why does the right ventricle perform less work than the left ventricle?

<p>Systolic pressure is less (C)</p> Signup and view all the answers

The P wave in an ECG primarily denotes which activity in the heart?

<p>Atrial depolarization (C)</p> Signup and view all the answers

Which condition is not associated with pure right ventricular failure?

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

Which vessel is primarily responsible for local regulation of blood flow?

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

Which of the following does not increase cardiac output?

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

What effect does stimulation of sympathetic nerves to the heart have?

<p>Makes the prepotential more horizontal (C)</p> Signup and view all the answers

Which statement correctly describes heart sounds?

<p>The first heart sound is due to closure of the aortic valve (A)</p> Signup and view all the answers

Which of the following does not increase heart rate?

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

What is a key consequence of stimulating sympathetic beta-1 receptors?

<p>Increased cardiac output (C)</p> Signup and view all the answers

In a normal ECG, the duration of the PQ interval is typically measured as:

<p>0.15 sec (C)</p> Signup and view all the answers

When does ventricular depolarization occur in relation to atrial excitation?

<p>0.2 seconds after atrial excitation (B)</p> Signup and view all the answers

What characterizes the isovolumetric relaxation phase of the ventricles?

<p>Closure of aortic valves (C)</p> Signup and view all the answers

What effect does a loss of one liter of blood have on baroreceptor activity?

<p>Increases their discharge (D)</p> Signup and view all the answers

In the context of a large infarct affecting the left ventricle, which parameter is likely to increase?

<p>Left ventricular end systolic pressure (B)</p> Signup and view all the answers

Which blood vessels are primarily responsible for the exchange between plasma and interstitial fluid?

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

Which cardiac fibers have the slowest conduction velocity for impulses?

<p>AV nodal fibers (C)</p> Signup and view all the answers

What is the effect of stimulating B-1 adrenergic receptors on heart rate?

<p>Increases heart rate (C)</p> Signup and view all the answers

Which parameter indicates a high preload in the cardiovascular system?

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

What consequence does aortic valve regurgitation lead to?

<p>Decrease in diastolic pressure (C)</p> Signup and view all the answers

Which factor contributes to a decreased stroke volume?

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

What effect does assuming an upright posture have on the cardiovascular system?

<p>Stimulation of the renin-angiotensin system (D)</p> Signup and view all the answers

What impact does an infusion of nor-adrenaline have on the cardiovascular system?

<p>Decrease in cardiac output (D)</p> Signup and view all the answers

Which of these actions results in generalized vasoconstriction?

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

Which of the following locations are associated with the presence of chemoreceptors?

<p>Carotid sinus (B), Glomus bodies (C), Aortic arch (D)</p> Signup and view all the answers

Which situation would lead to a decrease in central venous pressure?

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

Which factor is least likely to produce local vasodilation?

<p>A decrease in H+ concentration (A)</p> Signup and view all the answers

Which of the following factors is least expected to increase cardiac output?

<p>Moderate rise in environmental temperature (D)</p> Signup and view all the answers

The Frank-Starling law does not explain which of the following?

<p>Normal cardiac output in hypertensive patients (C)</p> Signup and view all the answers

Which type of drug is likely to increase heart rate from 70 to 100 beats per minute?

<p>A cholinergic receptor antagonist (B)</p> Signup and view all the answers

Excitation of the ventricles occurs in what manner?

<p>From subendocardium to subpericardium (C)</p> Signup and view all the answers

Which characteristic does not describe AV nodal cells?

<p>Exhibit rapid depolarization (C)</p> Signup and view all the answers

Flashcards

Pulmonary Artery Pressure (Systole)

Approximately 25 mmHg during systole in the pulmonary artery

Baroreceptor Location

Baroreceptors are found in the carotid sinuses and aortic arch, monitoring arterial blood pressure.

Chemoreceptor Stimulus

Chemoreceptors are primarily stimulated by increased carbon dioxide (hypercapnia) in the blood.

LV End-Systolic Volume (Resting)

Approximately 50 mL at rest, representing the blood remaining in the left ventricle after contraction.

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Mixed Venous PO2 Measurement

The best site to measure mixed venous PO2 is the pulmonary artery.

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Atrial Contraction's Role in Ventricular Filling

Atrial contraction contributes to approximately 10% of ventricular filling.

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Slowest Blood Flow

Blood flow is slowest in capillaries due to widespread vessel networks.

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Greatest Blood Volume Location

Veins contain the largest volume of blood in the circulatory system.

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Cardiac muscle refractory period

A long period of time during which the heart muscle cannot be stimulated to contract again.

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Baroreceptor stimulation effect

Stimulation of baroreceptors leads to a decrease in heart rate and blood pressure.

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Fourth heart sound cause

The fourth heart sound is caused by atrial systole (contraction of the atria).

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Frank-Starling's Law

The law states that the stroke volume of the heart increases in response to an increase in the end-diastolic volume.

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Right ventricle vs Left ventricle work

The right ventricle does less work than the left ventricle due to a thinner wall and lower afterload (resistance of the blood against outflow).

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Signs of pure right heart failure

Signs of pure right heart failure include increased central venous pressure, central venous engorgement/pulsations, hepatomegaly (enlarged liver), sacral edema, not pulmonary edema.

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Local blood flow regulation

Local blood flow is primarily regulated by arterioles (small arteries).

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Factors increasing heart rate (except)

Heart rate increases due to fever, increased venous return, and adrenaline. Hypothyroidism generally decreases the heart rate.

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Increased heart rate (70 to 100 bpm)

A heart rate increase from 70 to 100 beats per minute is likely caused by stimulation of beta-1 adrenergic receptors.

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High preload

High preload is indicated by a high end-diastolic volume.

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Aortic valve regurgitation

Aortic valve regurgitation leads to a systolic murmur and decreased diastolic pressure.

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Decreased stroke volume

A decreased stroke volume results from an increased afterload.

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Increased pulse pressure

Increased pulse pressure can result from aortic stenosis.

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Upright posture effect

Assuming an upright posture stimulates the renin-angiotensin system, reducing renal blood flow.

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Central venous pressure increase

Central venous pressure increases with increased total peripheral resistance, not hypovolemia or decreased cardiac output.

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Nor-adrenaline infusion effect

Nor-adrenaline infusion increases myocardial contractility and thus cardiac output while decreasing baroreceptor firing rate.

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Chemoreceptor Location

Chemoreceptors are specialized sensory cells that monitor the chemical composition of blood. They are found in the aortic arch, carotid sinuses, and glomus bodies.

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Local Vasodilation: Cause?

Local vasodilation, the widening of blood vessels in a specific area, can be triggered by various factors, including a decrease in oxygen levels (hypoxia), an increase in carbon dioxide levels (hypercapnia), and an increase in metabolic byproducts like lactic acid.

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Cardiac Output Increase: Exceptions

Cardiac output, the amount of blood the heart pumps per minute, increases with exercise, adrenaline, and moderate temperature rises. However, a significant increase in body temperature (above 10 degrees) can actually decrease cardiac output.

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Cardiac Cycle: Incorrect Statement

The second heart sound (S2) does not occur in late systole. Instead, it marks the beginning of ventricular diastole.

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Frank-Starling Law: Exception

The Frank-Starling law explains how the heart adjusts its output based on venous return, but it doesn't fully account for the increased contractility caused by sympathetic stimulation, which is a separate mechanism.

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Drug that Increases Heart Rate

A cholinergic receptor antagonist, which blocks the effects of acetylcholine, a neurotransmitter that slows heart rate, would lead to an increase in heart rate.

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Ventricular Excitation: Incorrect Statement

Ventricular excitation does not lead to excitation of the atria. The signal originates in the sinoatrial node and travels to the atria before reaching the ventricles.

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AV Nodal Cells: Unique Feature

AV nodal cells are specialized cells that conduct electrical impulses more slowly than atrial or ventricular cells, creating a delay that allows the atria to contract completely before the ventricles.

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Starling Mechanism

A mechanism in the heart that ensures both ventricles pump the same amount of blood with each beat, matching output for efficient circulation.

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Carotid Sinus Pressure Decrease

A drop in pressure in the carotid artery triggers an increase in heart rate and vasoconstriction to maintain blood pressure.

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QRS Wave in ECG

Represents the electrical activity during ventricular depolarization, the electrical signal that makes the ventricles contract.

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P Wave in ECG

The electrical signal that represents atrial depolarization, causing the atria to contract and push blood into the ventricles.

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Sympathetic Nerve Stimulation on Heart

Increases heart rate, strengthens contractions, and reduces the time between heartbeats, primarily through beta-adrenergic receptors.

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First Heart Sound

The sound produced when the atrioventricular valves (mitral and tricuspid) close at the beginning of ventricular contraction.

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PQ Interval Duration

The time between the start of the electrical signal in the atria (P wave) and the start of ventricular depolarization (QRS complex), typically about 0.12-0.20 seconds.

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Cardiac Output Increase

Factors that increase the force of heart contraction or the amount of blood returning to the heart enhance cardiac output.

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Venodilation Effect on Cardiac Output

Venodilation decreases cardiac output by reducing the amount of blood returning to the heart.

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Ventricular Depolarization Timing

Ventricular depolarization, the electrical activation of the ventricles, occurs shortly after atrial excitation and marks the beginning of ventricular systole.

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Isovolumetric Relaxation Phase

The isovolumetric relaxation phase occurs at the beginning of diastole, where the ventricles relax, but the valves are closed, so the volume remains constant.

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Stroke Volume: Factors that Increase It

Increased preload (end-diastolic volume), increased contractility, and decreased afterload all increase stroke volume.

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Blood Loss and Heart Rate Response

Blood loss triggers an increased heart rate, stimulated by baroreceptors that detect the decreased blood pressure.

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Left Ventricular Infarct and Effects

A large infarct affecting the left ventricle reduces its ability to pump blood, leading to decreased cardiac output and increased pressure within the ventricle.

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Capillary Exchange: Key Vessels

Capillaries are the primary blood vessels responsible for the exchange of nutrients, oxygen, and waste products between blood and tissues.

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Study Notes

Cardiovascular System

  • Arterial Pressure Reflex: Includes decreased firing of carotid sinus baroreceptors, increased sympathetic activity to the ventricles, and increased parasympathetic activity affecting arterioles in skeletal muscles and skin.

  • Hemorrhage Compensation: The correct sequence includes decreased arterial pressure triggering increased baroreceptor firing, leading to increased release of renin by the kidneys. This, in turn, leads to formation of Angiotensin II, followed by decreased excretion of sodium (Na⁺) and water, which prompts the increased production of aldosterone. Ultimately, reduced atrial volume prompts the increase in volume receptor firing rate.

  • Venous Return: Venous return is increased by venoconstriction and decreased by deep inspiration. It activates the Bainbridge reflex when increased.

  • Heart Nerve Supply: The SA node is innervated by the sympathetic nervous system. Atrial muscle receives both sympathetic and parasympathetic innervation. The right vagus nerve supplies the SA and AV nodes, while the left vagus nerve supplies the SA node. The parasympathetic nervous system supplies ventricular muscle.

  • Cardiac Muscle Characteristics: Cardiac muscle is a syncytium, meaning it's interconnected. It has intercalated discs and gap junctions, which contribute to the spread of depolarization. It also contains actin and myosin, the protein components necessary for contraction.

  • Pacemaker Prepotential: The pacemaker prepotential is a slow increase in the resting membrane potential, primarily maintained by the opening of long-acting calcium channels. It occurs only in the SA node.

  • Parasympathetic Stimulation: Results in increased potassium efflux in cardiac muscles, increasing calcium influx in the SA node, and bradycardia.

  • Cardiac Muscle Electrical Activity: Increased extracellular potassium causes depolarization, while repolarization is associated with sodium current. Plateau of the action potential in cardiac muscle is caused by an influx of calcium ions, while the initial repolarization involves delayed potassium efflux.

  • Heart Conduction System: The conductive system of the heart does not inherently include the interventricular septum.

  • ECG Characteristics: An ECG measures electrical activity and is useful in detecting arrhythmias, with specific waveforms representing different phases of electrical activity in the cardiac cycle. The amplitude indicates the cardiac muscle mass, and the PR-interval represents the strength of the contraction.

  • Cardiac Cycle: The cardiac cycle involves ventricular diastole following atrial systole. AV valves close at the beginning of ventricular systole, and the first heart sound signifies the closure of the AV valves. The second heart sound is due to the closure of semilunar valves. Isovolumetric relaxation occurs at the end of diastole.

  • Atrial Pressure Wave: The A wave of the atrial pressure wave is directly caused by atrial systole.

  • Pulmonary Artery Pressure: Pulmonary artery pressure is lower than pressure in the right ventricle, and less than in the right atrium.

  • Chemoreceptors: Located in the aortic arch and carotid sinuses, these monitor arterial blood pressure and are stimulated by abnormal blood gases. Chemoreceptors transmit signals to the vasomotor center, which influences vessel diameter. They are stimulated by hypercapnia (increased CO2).

  • Left Ventricular End-Systolic Volume: Resting LV end-systolic volume is about 50 mL.

  • Mixed Venous PO2 Measurement: The best location to measure mixed venous PO2 is the pulmonary artery.

  • Atrial Contraction Influence on Ventricular Filling: Atrial contraction represents approximately 20-30% of the normal ventricular filling volume.

  • Cardiac Output: The cardiac output equals the product of stroke volume and the heart rate. The values can vary based on different conditions.

  • Factors Affecting Stroke Volume: Stroke volume increases with increased end-diastolic volume (preload).

  • Effects of Increased Stroke Volume: An increased stroke volume can result from an increase in end-diastolic volume or a decrease in end-systolic volume, which can be influenced by factors like sympathetic stimulation or exercise.

  • Heart Sounds in the Cardiac Cycle: The first heart sound (S1) is due to closure of the AV valves, and the second heart sound (S2) corresponds to closure of the semilunar valves.

  • Noradrenaline Infusion: Noradrenaline infusion leads to an enhanced firing rate of baroreceptors, bradycardia, a reduced peripheral resistance, and myocardial contractility boost, along with an elevated cardiac output.

  • Factors Influencing Cardiac Output: Factors affecting cardiac output include heart rate, stroke volume, and venous return.

  • Pacemaker Location and Function: The sinoatrial (SA) node is the primary pacemaker because its cells naturally fire/discharge at the fastest rate.

  • Cardiovascular Factors: Various factors like blood volume, stroke volume, preload, afterload, and heart rate can affect cardiovascular performance.

  • Drugs and Cardiac Function: Some drugs affect cardiac function by interacting with specific receptors, such as adrenergic or cholinergic receptors.

  • Coronary Blood Flow: Coronary blood flow, essential for myocardial perfusion, is primarily regulated by sympathetic stimulation, is maximized during diastole, and increases with myocardial metabolism.

  • and many more...

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Description

This quiz covers key concepts related to the cardiovascular system, including arterial pressure reflexes, compensation mechanisms for hemorrhage, venous return, and the nerve supply to the heart. Test your understanding of how these components work together to maintain cardiovascular health.

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