Cardiovascular System Practice Questions

Q: Ejection fraction increases with:

End diastolic volume.. **Explanation:** **Ejection Fraction (EF)** is the percentage of blood pumped out of the left ventricle with each contraction. It is calculated using the formula: **EF = (Stroke Volume / End Diastolic Volume) × 100**, where Stroke Volume (SV) = EDV – ESV. **Why End Diastolic Volume (EDV) is correct:** According to the **Frank-Starling Law**, an increase in EDV (preload) leads to increased stretching of the ventricular myocardial fibers. This increases the force of contraction, thereby increasing the Stroke Volume. While both the numerator (SV) and denominator (EDV) increase, the physiological response to increased filling in a healthy heart typically results in a more efficient contraction, maintaining or increasing the EF. **Analysis of Incorrect Options:** * **A. End Systolic Volume (ESV):** EF is inversely proportional to ESV. An increase in ESV (the blood remaining after contraction) indicates a decrease in stroke volume and myocardial contractility, leading to a **decrease** in EF. * **C. Peripheral Vascular Resistance (Afterload):** Increased resistance (e.g., hypertension) makes it harder for the heart to pump blood. This increases ESV and decreases SV, thereby **decreasing** the EF. * **D. Venodilation:** This increases venous capacitance and reduces venous return to the heart. This leads to a **decrease** in EDV (preload), which subsequently reduces SV and EF. **High-Yield Clinical Pearls for NEET-PG:** * **Normal EF:** 55% to 70%. An EF < 40% usually indicates Heart Failure with Reduced Ejection Fraction (HFrEF). * **Best Index of Myocardial Contractility:** While EF is commonly used, **dP/dt max** (rate of pressure rise) is considered the most accurate index. * **Inotropic Effect:** Positive inotropes (like Digoxin or Adrenaline) increase EF by decreasing ESV.

Q: Regarding the calculation of stroke volume, which of the following statements is NOT true?

Stroke Volume = Ejection Fraction x Cardiac Output. ### Explanation **1. Why Option B is the Correct Answer (The False Statement):** Stroke Volume (SV) is the volume of blood pumped by the left ventricle per heartbeat. The **Ejection Fraction (EF)** is defined as the fraction of the End-Diastolic Volume (EDV) that is ejected during a contraction. Mathematically, $EF = SV / EDV$. Therefore, the correct relationship is **$SV = EF \times EDV$**. Option B is incorrect because multiplying Ejection Fraction by Cardiac Output (CO) has no physiological basis; Cardiac Output is already a product of Stroke Volume and Heart Rate ($CO = SV \times HR$). **2. Analysis of Other Options:** * **Option A:** This is a **true** statement derived directly from the definition of Ejection Fraction ($SV = EF \times EDV$). It represents the efficiency of the pump. * **Option C:** This is a **true** statement derived from the Cardiac Output formula ($CO = SV \times HR$). By rearranging it, $SV = CO / HR$. This is commonly used in clinical settings to calculate SV from thermodilution or Fick’s method data. **3. NEET-PG High-Yield Clinical Pearls:** * **Normal Values:** In a healthy 70kg adult, SV is approximately **70 mL**, EDV is **120 mL**, and ESV (End-Systolic Volume) is **50 mL**. * **Ejection Fraction (EF):** Normal range is **55–70%**. An EF < 40% is a hallmark of systolic heart failure (HFrEF). * **Determinants of SV:** Stroke volume is determined by three factors: **Preload** (proportional), **Afterload** (inversely proportional), and **Inotropy** (proportional). * **Fick’s Principle:** Remember that $CO = \text{Oxygen Consumption} / (\text{Arterial } O_2 \text{ content} - \text{Venous } O_2 \text{ content})$. This is a frequent numerical target in exams.

Q: The 'C' wave in the Jugular Venous Pulse (JVP) waveform represents which event?

Tricuspid valve bulging into the right atrium. The Jugular Venous Pulse (JVP) reflects pressure changes in the right atrium. Understanding its waveform is a high-yield topic for NEET-PG. ### **Explanation of the Correct Answer** The **'c' wave** occurs during **isovolumetric ventricular contraction**. As the right ventricle begins to contract, the intraventricular pressure rises sharply, causing the **tricuspid valve to bulge back into the right atrium**. This transient increase in atrial pressure creates the 'c' wave. (Note: Carotid artery pulsation may also contribute slightly to this wave). ### **Analysis of Incorrect Options** * **A. Atrial contraction:** This corresponds to the **'a' wave**. It is the first positive deflection and occurs at the end of diastole. * **C. Ventricular systole:** While the 'c' wave occurs *during* early systole, the term is too broad. The 'x' descent (atrial relaxation) and 'v' wave (venous filling) also occur during different phases of ventricular systole. * **D. Rapid ventricular filling:** This occurs during early diastole and corresponds to the **'y' descent**, as blood flows from the atrium into the ventricle after the tricuspid valve opens. ### **High-Yield Clinical Pearls for NEET-PG** * **Giant 'a' waves:** Seen in Tricuspid Stenosis, Pulmonary Hypertension, and Pulmonary Stenosis (conditions where the atrium contracts against resistance). * **Cannon 'a' waves:** Occur when the atrium contracts against a closed tricuspid valve (e.g., Complete Heart Block, Ventricular Tachycardia). * **Absent 'a' wave:** Pathognomonic for **Atrial Fibrillation**. * **Giant 'v' waves:** Characteristic of **Tricuspid Regurgitation** (due to blood regurgitating into the atrium during systole).

Q: Two vessels are compared as shown in the diagram. Assuming constant pressure along both vessels and a linear flow pattern, what will be the flow across vessel 1 compared to vessel 2?

8 times. ***8 times*** - According to **Poiseuille's law** (Q ∝ r⁴/L), flow is proportional to the fourth power of radius divided by length. - With vessel 1 having **2r radius** and **2L length** vs vessel 2's **r radius** and **L length**: Q₁/Q₂ = (2r)⁴×L / (r⁴×2L) = 16r⁴L / 2r⁴L = **8 times**. *2 times* - This represents a **linear relationship** with radius, ignoring the **fourth power dependency** in Poiseuille's law. - Also incorrectly assumes flow is directly proportional to radius rather than r⁴, missing the exponential relationship. *4 times* - This reflects considering only the **radius squared** (2²) effect while neglecting both the **fourth power** and **length correction**. - Common error when confusing **cross-sectional area** (πr²) with flow dynamics governed by **viscous resistance**. *16 times* - This considers only the **radius to the fourth power** (2⁴ = 16) while completely **ignoring the length factor**. - Fails to account that vessel 1 has **double the length**, which **halves the flow** according to Poiseuille's law.

Q: Mean aerial pressure is calculated as:

(SBP + 2DBP)/ 3. **Explanation:** **1. Understanding the Correct Answer (A):** Mean Arterial Pressure (MAP) is defined as the average pressure in a patient's arteries during one full cardiac cycle. It is considered a better indicator of perfusion to vital organs than systolic blood pressure alone. The formula is derived from the fact that the heart spends more time in **diastole** (relaxation) than in **systole** (contraction). At a normal resting heart rate, approximately **two-thirds (2/3)** of the cardiac cycle is spent in diastole and **one-third (1/3)** in systole. Therefore, the weighted average is: * **MAP = [1/3 (SBP) + 2/3 (DBP)]**, which simplifies to **(SBP + 2DBP) / 3**. Alternatively, since Pulse Pressure (PP) = SBP - DBP, the formula can also be written as: **MAP = DBP + 1/3 (Pulse Pressure)**. **2. Why Other Options are Incorrect:** * **Option B:** This incorrectly weights Systole more than Diastole. This would only be true if the heart spent most of its time contracting, which would lead to myocardial exhaustion. * **Options C & D:** These options use a divisor of 2, which represents a simple arithmetic mean. This is physiologically inaccurate because the cardiac cycle is not split 50/50 between systole and diastole. **3. NEET-PG High-Yield Clinical Pearls:** * **Critical Threshold:** A MAP of **≥ 65 mmHg** is generally required to maintain adequate tissue perfusion (especially for the kidneys and brain). * **Tachycardia Impact:** As heart rate increases, the duration of diastole shortens significantly. In severe tachycardia, the 1/3–2/3 ratio shifts, and the simple formula becomes less accurate. * **Organ Perfusion:** While SBP indicates the workload of the heart, MAP is the driving force for tissue blood flow.

Q: Epinephrine increases heart rate by its action on which of the following?

Phospholamban. **Explanation:** Epinephrine (Adrenaline) increases heart rate (positive chronotropy) and contractility (positive inotropy) primarily by stimulating **$\beta_1$-adrenergic receptors** in the myocardium. **Mechanism of Action:** 1. Stimulation of $\beta_1$ receptors activates **Adenyl Cyclase**, increasing intracellular **cAMP**. 2. cAMP activates **Protein Kinase A (PKA)**. 3. PKA phosphorylates **Phospholamban**, a protein that normally inhibits the **SERCA** (Sarcoplasmic Reticulum Ca²⁺-ATPase) pump. 4. Once phosphorylated, Phospholamban's inhibitory effect is removed, allowing SERCA to rapidly sequester calcium back into the sarcoplasmic reticulum. 5. This accelerates relaxation (lusitropy) and increases the calcium "load" available for the next contraction, leading to an increased heart rate and force. **Analysis of Incorrect Options:** * **A. Calmodulin:** A calcium-binding messenger protein that mediates various cellular processes (like smooth muscle contraction) but is not the primary target for epinephrine’s chronotropic effect. * **B. Calsequestrin:** A calcium-binding protein located *inside* the sarcoplasmic reticulum that helps store high concentrations of Ca²⁺; it does not regulate the rate of contraction via the $\beta$-pathway. * **C. Calreticulin:** A multifunctional protein that acts as a calcium buffer in the *endoplasmic* reticulum; it is not involved in the acute adrenergic regulation of heart rate. **High-Yield Clinical Pearls for NEET-PG:** * **Lusitropy:** The term for myocardial relaxation. Phospholamban phosphorylation is the key mediator of catecholamine-induced lusitropy. * **SERCA2:** The specific isoform of the calcium pump found in cardiac muscle. * **Inamrinone/Milrinone:** These PDE3 inhibitors increase cAMP levels, mimicking the effect of epinephrine on phospholamban, used in acute heart failure.

Q: Edema may be caused by any of the following, EXCEPT:

An increase in the plasma protein concentration. ### Explanation The movement of fluid between the vascular space and the interstitium is governed by **Starling’s Forces**. Edema occurs when there is an imbalance in these forces, leading to excessive fluid accumulation in the interstitial space. **Why Option A is the Correct Answer:** **Plasma Colloid Osmotic Pressure (πp)**, primarily exerted by albumin, is the force that **draws fluid into** the capillary from the interstitium. An **increase** in plasma protein concentration raises this osmotic pressure, which promotes fluid retention within the vessels and opposes edema formation. Conversely, *hypoalbuminemia* (low protein) is a classic cause of edema. **Why the other options are incorrect (Causes of Edema):** * **B. Increased Capillary Hydrostatic Pressure:** This "pushes" fluid out of the vessels. Common in Heart Failure (systemic edema) or Deep Vein Thrombosis (localized edema). * **C. Increased Capillary Permeability:** When the "sieve" becomes leaky, proteins and fluid escape into the interstitium. This is seen in inflammation, burns, and allergic reactions (Type I hypersensitivity). * **D. Lymphatic Obstruction:** The lymphatic system normally drains the small amount of protein and fluid that leaks into the interstitium. Obstruction (e.g., Filariasis or post-mastectomy) leads to **Lymphedema**. ### High-Yield NEET-PG Pearls: * **Starling’s Equation:** $Net\ Fluid\ Movement = K_f [(P_c - P_i) - \sigma(\pi_p - \pi_i)]$ * **Most important protein** for maintaining oncotic pressure: **Albumin**. * **Myxedema:** A non-pitting edema seen in hypothyroidism caused by the accumulation of glycosaminoglycans (hyaluronic acid) in the dermis, not just fluid imbalance. * **Safety Factors against Edema:** Negative interstitial fluid pressure, high lymph flow, and "washout" of interstitial proteins.

Question 1

Myocardial oxygen demand depends upon which of the following factors?

Accepted Answer

Preload

Answer

Afterload

Answer

Intramyocardial tension

Answer

Blood hemoglobin concentration

Question 2

What effect does parasympathetic stimulation have on the heart?

Accepted Answer

Decreased firing rate of the SA node

Answer

Increased excitability of the AV node

Answer

Decreased ventricular contractility

Answer

Tachycardia

Question 3

Ejection fraction increases with:

Accepted Answer

End diastolic volume.

Answer

End systolic volume.

Answer

Peripheral vascular resistance.

Answer

Venodilation.

Question 4

Regarding the calculation of stroke volume, which of the following statements is NOT true?

Accepted Answer

Stroke Volume = Ejection Fraction x Cardiac Output

Answer

Stroke Volume = Ejection Fraction x End-Diastolic Volume

Answer

Stroke Volume = Cardiac Output / Heart Rate

Answer

None of the above

Question 5

The 'C' wave in the Jugular Venous Pulse (JVP) waveform represents which event?

Accepted Answer

Tricuspid valve bulging into the right atrium

Answer

Atrial contraction

Answer

Ventricular systole

Answer

Rapid ventricular filling

Question 6

Which of the following is most appropriate regarding the regulation of coronary circulation?

Accepted Answer

Autoregulatory mechanisms

Answer

Autonomic regulation

Answer

Hormonal influences

Answer

Sympathetic nervous system control

Question 7

Two vessels are compared as shown in the diagram. Assuming constant pressure along both vessels and a linear flow pattern, what will be the flow across vessel 1 compared to vessel 2?

Accepted Answer

8 times

Answer

2 times

Answer

4 times

Answer

16 times

Question 8

Mean aerial pressure is calculated as:

Accepted Answer

(SBP + 2DBP)/ 3

Answer

(DBP + 2SBP)/ 3

Answer

(SBP + 3DBP)/ 2

Answer

(DBP + 3SBP)/ 2

Question 9

Epinephrine increases heart rate by its action on which of the following?

Accepted Answer

Phospholamban

Answer

Calmodulin

Answer

Calsequestrin

Answer

Calreticulin

Question 10

Edema may be caused by any of the following, EXCEPT:

Accepted Answer

An increase in the plasma protein concentration

Answer

An increase in the capillary hydrostatic pressure

Answer

An increase in the capillary permeability

Answer

Lymphatic obstruction

Cardiovascular System — MCQs

Cardiovascular System — MCQs

On this page

Practice by Chapter

Want unlimited practice?