Cardiovascular Physiology Quiz

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Questions and Answers

If the duration of ventricular diastole shortens, what impact does this have on end-diastolic volume (EDV) and stroke volume (SV)?

EDV increases, SV decreases

EDV increases, SV increases

EDV decreases, SV increases

EDV decreases, SV decreases (correct)

Which of the following factors directly influences preload?

Blood pressure

Heart rate

Contractility

Venous return (correct)

According to the Frank-Starling law of the heart, what happens to the force of contraction when the heart is stretched more?

The force of contraction remains constant.

The force of contraction increases. (correct)

The force of contraction decreases.

The force of contraction fluctuates unpredictably.

How does increased venous return impact stroke volume?

Increased venous return increases stroke volume. (C) Signup and view all the answers

Which of the following is NOT a factor that regulates stroke volume?

Heart rate (B) Signup and view all the answers

What is the relationship between contractility and EDV?

Contractility is independent of EDV. (D) Signup and view all the answers

How does increased afterload impact stroke volume?

Increased afterload decreases stroke volume. (C) Signup and view all the answers

What is the primary role of the heart in the circulatory system?

To pump blood throughout the body. (C) Signup and view all the answers

What is the primary effect of increased afterload on the heart?

Decreased ventricular filling time. (B), Decreased stroke volume. (C) Signup and view all the answers

Which scenario is most likely to lead to a decrease in stroke volume (SV)?

Increased afterload due to aortic stenosis. (B) Signup and view all the answers

What is the physiological mechanism that leads to concentric hypertrophy in pressure overload states?

Decreased wall stress through radius reduction or increased wall thickness. (A) Signup and view all the answers

Which of these conditions is most likely to cause diastolic heart failure?

Pericardial effusion. (B) Signup and view all the answers

What is the key physiological difference between systolic and diastolic heart failure?

Systolic heart failure involves impaired ventricular relaxation, while diastolic heart failure involves impaired ventricular contraction. (D) Signup and view all the answers

How does an impaired ventricular relaxation (as in diastolic heart failure) contribute to the disease?

It reduces the time available for ventricular filling during diastole. (A) Signup and view all the answers

What is a common physiological mechanism that can contribute to both systolic and diastolic heart failure?

Decreased myocardial contractility. (D) Signup and view all the answers

Which of these options is NOT a key characteristic of diastolic heart failure?

Decreased stroke volume. (B) Signup and view all the answers

Which layer of the heart wall is responsible for the heart's contraction?

Myocardium (C) Signup and view all the answers

What type of heart disease is defined as being present from birth?

Congenital heart disease (B) Signup and view all the answers

What term refers to diseases affecting the heart and blood vessels?

Cardiovascular disease (A) Signup and view all the answers

Which layer of the heart is known as the outer serous covering?

Epicardium (D) Signup and view all the answers

How can heart diseases commonly be inherited in animals?

Through genetics (B) Signup and view all the answers

Which statement about the endocardium is true?

It helps line the heart and blood vessels (C) Signup and view all the answers

What is the name of disorders affecting the valves of the heart?

Valvular disorders (D) Signup and view all the answers

Which heart disease category does not typically develop as a result of genetics?

Infective endocarditis (B) Signup and view all the answers

What is a primary characteristic of low-output heart failure?

Decreased pumping into the aorta and pulmonary artery (B) Signup and view all the answers

Which of the following signs is indicative of congestive heart failure in right-sided CHF?

Ascites (A) Signup and view all the answers

How can congestive heart failure (CHF) manifest depending on the side of heart failure?

Through both systemic and pulmonary congestion (D) Signup and view all the answers

Which symptom is NOT commonly associated with low cardiac output?

Dyspnea (C) Signup and view all the answers

What distinguishes right-sided CHF from left-sided CHF?

Systemic circulation congestion is characteristic of right-sided CHF (A) Signup and view all the answers

Which condition is characterized by an inability to pump blood effectively into the aorta?

Low-output heart failure (A) Signup and view all the answers

What is a common sign of congestion in congestive heart failure?

Pulmonary edema (B) Signup and view all the answers

What are the potential outcomes of decompensated heart failure?

Progression to severe heart failure or death (B) Signup and view all the answers

What is the primary physiological effect of an increase in heart rate on cardiac output?

Initially increases cardiac output linearly, but eventually plateaus and may even decrease. (A) Signup and view all the answers

Which of the following factors directly influences stroke volume?

The resistance the ventricle encounters as it ejects blood. (D) Signup and view all the answers

What is the physiological effect of an increase in afterload on stroke volume?

Reduces stroke volume because the ventricle has to work harder against increased resistance. (D) Signup and view all the answers

What is the physiological relationship between cardiac output and stroke volume?

Cardiac output is directly proportional to stroke volume, meaning a larger stroke volume always leads to a higher CO. (D) Signup and view all the answers

What is the physiological consequence of a decrease in stroke volume on cardiac output?

Decreases cardiac output due to the reduced volume of blood ejected per beat. (A) Signup and view all the answers

What is the primary mechanism by which heart failure can lead to a decrease in arterial blood pressure?

Decreased contractility, which reduces the force of blood ejection. (D) Signup and view all the answers

What is the relationship between stroke volume and heart rate in regulating cardiac output?

Both stroke volume and heart rate contribute to cardiac output, and changes in either factor can influence CO. (C) Signup and view all the answers

What is the primary physiological effect of the parasympathetic nervous system on heart rate?

Decreases heart rate by slowing down the rate of electrical conduction in the heart. (B) Signup and view all the answers

In the context of heart failure, how does chronic adrenergic stimulation contribute to the progression of the condition?

It triggers an increase in afterload, contributes to ventricular arrhythmias, and deteriorates left ventricular function. (C) Signup and view all the answers

Which of the following accurately describes the mechanism behind the decreased contractile response of the heart in heart failure, despite increased plasma norepinephrine levels?

Depletion of norepinephrine stores in the atria and ventricles, resulting from β-adrenoreceptor downregulation. (C) Signup and view all the answers

Identify the primary mechanism responsible for the decline in both systolic and diastolic function observed as interstitial fibrosis progresses in heart failure.

Individualization of cardiac myocytes and fibrotic scar tissue, hindering both the contraction and relaxation phases of the heart. (C) Signup and view all the answers

Why is the ischemia resulting from hypertrophy and stretching in heart failure a significant contributor to the deterioration of cardiac function?

It increases the workload of the heart, leading to increased energy demands that exceed the supply, ultimately damaging cardiomyocytes. (D) Signup and view all the answers

Which of the following represents a key feature of the neuroendocrine compensatory mechanisms in heart failure?

Vasoconstriction and sodium and water retention, contributing to an increase in preload and afterload. (D) Signup and view all the answers

In the context of heart failure, what is the significance of the change in the ratio of β1 to β2 receptors from 80:20 in a normal heart to 60:40 in a failing heart?

It contributes to the decrease in contractile response, reducing the heart's ability to pump blood effectively. (D) Signup and view all the answers

Which of the following accurately depicts the role of myocardial cell death and cardiac fibrosis in the progression of heart failure?

They contribute to the deterioration of the heart's ability to pump blood effectively, leading to a vicious cycle of progressive heart failure. (A) Signup and view all the answers

How does Cycle 1, as described in the text, contribute to the progression of left heart failure?

By increasing myocardial wall stress, leading to hypertrophy and further deterioration of cardiac function. (A) Signup and view all the answers

Study Notes

Physiopathology I - Course Information

Course title: Physiopathology I
Instructor: Dr. Rana CHAAYA
Semester: Fall 2021
University: Université Libanaise - Faculté d'agronomie Et de médecine Vétérinaire

References for Animal Pathophysiology

Pathologic Basis of Veterinary Disease: 5th edition, Edited by James F. Zachary DVM PhD (Editor), M. Donald McGavin MVSc PhD FACVSC, Published by Elsevier.
Essentials of Pathophysiology: 3rd edition, by Carol Mattson Porth, Published by Wolters Kluwer.
Veterinary Pathophysiology: Edited by Robert H. Dunlop and Charles-Henri Malbert, Published by Blackwell Publishing.

Cardiovascular Diseases

Pathophysiology I: Pathology of Organ Systems: This section covers various diseases related to organ systems, including cardiovascular diseases.
Topics covered include: Cardiovascular Diseases, Respiratory Diseases, Nervous Diseases, Urinary Diseases.

Part 1: Cardiovascular Diseases

Chapter 1: Dysfunction/Responses to Injury
Chapter 2: Congenital Heart Defects
Chapter 3: Endocardial and valvular disorders
Chapter 4: Disorders of the Pericardium & Cardiomyopathies

Chapter 1: Dysfunction/Responses to Injury

Blood Circulation: Describes systemic and pulmonary circulations. Diagram illustrates the flow of blood through the heart and the rest of the body excluding the lungs, showing pulmonary arteries, pulmonary veins, systemic arteries, left atrium, and right ventricle etc.

Heart Anatomy

The heart wall has three layers: the epicardium (visceral pericardium—outer serous covering), the myocardium (thickest part, cardiac muscle), and the endocardium (inner layer of endothelium).
Cardiac muscle fiber contraction results in the heartbeat.

What is Heart Disease?

Cardiovascular disease is any condition affecting the heart and blood vessels that disrupt the delivery of oxygenated blood to the body.
Heart disease can be congenital (present at birth) or acquired (develop later).
Many heart diseases are hereditary and are common in specific breeds of animals.

Pathophysiologic Mechanisms of Cardiovascular Dysfunction

Pump failure: Weak contractility and emptying of heart chambers, impaired filling of chambers.
Obstruction to forward blood flow: Valvular stenosis, vascular narrowing, systemic or pulmonary hypertension.
Regurgitant blood flow: Volume overload of the chamber behind a failing valve.
Shunted blood flow: From congenital defects (e.g., septal defects).
Rupture of the heart or a major vessel: Cardiac tamponade, massive internal hemorrhage.
Cardiac conduction disorders (arrhythmias): Failure of synchronized cardiac contraction.

Dysfunction: Heart Failure

Heart failure is a progressive clinical syndrome involving impaired pumping leading to decreased ventricular ejection and venous return.
Heart failure can involve low-output (decreased blood pumping) or it can involve congestion (inability to empty venous reservoirs).
Low cardiac output can cause lethargy, syncope, and hypotension.
Congestive heart failure can cause ascites, pleural effusion, and pulmonary edema.

Syndromes of Cardiac Failure or Decompensation:

Congestive Heart Failure (CHF) can be right-sided, left-sided, or bilateral, and can occur with cardiac dilation and/or hypertrophy.
Right-sided CHF usually manifests with signs of systemic congestion (ascites and peripheral edema).
Left-sided CHF presents with pulmonary congestion (pulmonary edema and dyspnea). This often shows up in small animals with pleural effusion.

Cardiac Anatomy and Dysfunction

Cardiac Dilation and Hypertrophy: Illustrates visual and structural differences in normal, dilated, and hypertrophied hearts with diagrams (transected ventricles)
Responses of the Myocardium to Injury: Discusses disorders resulting from circulation impairment, growth disturbances (atrophy (dilation), hypertrophy, genesis (aplasia), hypoplasia, dysplasia (dysgenesis)), cellular degeneration (cell and metabolic dysfunction, oncotic necrosis apoptosis), and inflammation
Cardiac Output: Explains the relationship between heart rate, stroke volume, and cardiac output. Increases in heart rate initially increase cardiac output proportionally, but eventually, further increases in heart rate lower cardiac output due to insufficient diastolic filling time.

Regulation of Stroke Volume

Preload: Volume of blood in the ventricles at the end of diastole. Increased preload stretches the heart, making contractions more efficient (Frank-Starling law),
Afterload: Resistance the ventricle must overcome to circulate blood. Increase in afterload reduces stroke volume, as it takes more effort for the ventricle to eject blood. Causes include hypertension or vascular narrowing (e.g., arteriosclerosis).

Regulation of Stroke Volume: Contractility

Factors increasing contractility: positive inotropic agents (e.g., glucagon, thyroxine, norepinephrine) that increase Ca2+ flow
Factors decreasing contractility: negative inotropic agents (e.g., anoxia, acidosis, increased extracellular K+ levels, calcium channel blockers)

Regulation of Stroke Volume: Afterload

Afterload is the pressure the heart must overcome to eject blood from the ventricles during systole.
Factors that increase afterload (e.g., hypertension, vascular narrowing) decrease stroke volume by increasing the workload.

Systolic and Diastolic Heart Failure

Systolic Heart Failure: Occurs when the heart has impaired ability to contract enough for proper blood ejection (ejection fraction decreased). This can be caused by Myocardial failure (primary or secondary), and volume overload. Common causes for pressure overload include aortic/pulmonic stenosis, as well as hypertension.
Diastolic Heart Failure: The heart is unable to properly relax and fill with blood, and subsequent reduced cardiac output. This is categorized by Impaired Energy Dependent Relaxation, Obstruction, and Pericardial Abnormalities

A-Concentric Hypertrophy, B-Eccentric Hypertrophy

Concentric hypertrophy: Occurs in pressure overload, resulting in increased resistance which leads to ventricular wall thickening and smaller chamber size to regulate wall stress.
Eccentric hypertrophy: Occurs in volume overload, increasing chamber size and causing lesser increase in wall stress compared to concentric hypertrophy.

Neuroendocrine Compensatory Mechanisms in Heart Failure

Chronic activation of the neuroendocrine system in heart failure causes vasoconstriction, sodium and water retention for restoring and maintaining blood pressure (ABP), leading eventually to myocardial and vascular remodeling contributing to further cardiac dysfunction and persistent neuroendocrine activation.

Role of Catecholamines in the Progression of Heart Failure

Increased norepinephrine (NE) in the plasma is a common result of CHF.
The increase in norepinephrine leads to depletion of NE stores in the atria and ventricles, reducing the effect of sympathetic stimulation on the myocardium.
Changes in receptor sensitivity and decreased stores of NE result in reduced contractility and positive chronotropy, which are commonly seen progressing left heart failure.

Summary of Pathophysiology of Heart Failure

Long-term overloaded heart leads to cardiac hypertrophy, myocardial cell death, and fibrosis (cardiomyopathy).
Ischemia from hypertrophy and expansion can cause further issues, such as loss of contractile strength.
These issues lead to cardiac atrophy and myocardial fibrosis, impacting diastolic function.
Chronic heart failure (CHF) involves both systolic and diastolic dysfunction and is ultimately a progressive and irreversible disease leading to death.

Pathophysiological cycles of progressive left heart failure

Increased vascular resistance causes Myocardial Hypertrophy
Water and Sodium retention leads to increased preload and vascular congestion.
Neuroendocrine activation results in myocardium and vascular remodeling

Pathophysiology of heart failure

Shows the interconnectedness of different cycles and their cumulative effects on the heart, leading to progressively severe heart failure.

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Description

This quiz tests your understanding of key concepts in cardiovascular physiology, including ventricular diastole, preload factors, and the Frank-Starling law. You'll explore how various physiological mechanisms influence stroke volume and heart function. Perfect for students studying heart mechanics and circulatory dynamics.