Cardiovascular System Practice Questions

Q: The dicrotic notch on an arterial pressure waveform corresponds to which event?

Closure of the aortic and pulmonic valves. **Explanation:** The **dicrotic notch (incisura)** is a brief downward deflection observed on the descending limb of the arterial pressure waveform. It marks the physiological end of systole and the beginning of diastole. **Why Option B is correct:** When the left ventricle finishes ejecting blood, the pressure within the ventricle drops below the pressure in the aorta. This pressure gradient causes a brief retrograde flow of blood toward the heart, which snaps the **aortic valve shut** (and similarly the pulmonic valve in the pulmonary artery). This sudden closure causes a momentary rebound of blood against the closed valve leaflets, creating a small pressure spike or "notch" before the pressure continues to decline during diastole. **Why the other options are incorrect:** * **Options A & C:** The closure and opening of atrioventricular (mitral/tricuspid) valves are associated with the **Atrial Pressure Waveform** (a, c, and v waves) and heart sounds ($S_1$ and $S_3/S_4$), but they do not directly produce the dicrotic notch on an *arterial* tracing. * **Option D:** The opening of the semilunar valves marks the beginning of the **anacrotic limb** (the rapid upstroke) of the arterial pulse, not the notch. **High-Yield Facts for NEET-PG:** * **Dicrotic Notch vs. Dicrotic Wave:** The *notch* is the dip caused by valve closure; the *wave* is the subsequent small rise in pressure. * **Loss of Dicrotic Notch:** Often seen in **Aortic Regurgitation** because the valve fails to close properly, preventing the rebound effect. * **Anacrotic Notch:** A notch on the *ascending* limb, classically seen in **Aortic Stenosis**. * **Phonocardiography Correlation:** The dicrotic notch coincides with the **second heart sound ($S_2$)**.

Q: What is the normal Pulmonary Capillary Wedge Pressure (PCWP)?

6-12 mm Hg. **Explanation:** **Pulmonary Capillary Wedge Pressure (PCWP)** is a crucial hemodynamic parameter measured using a Swan-Ganz catheter. It provides an indirect estimate of the **Left Atrial Pressure (LAP)** and, by extension, the Left Ventricular End-Diastolic Pressure (LVEDP), assuming there is no mitral valve obstruction. 1. **Why Option A is Correct:** The normal physiological range for PCWP is **6–12 mm Hg**. This pressure reflects the "back pressure" from the left side of the heart. It must remain low to facilitate efficient gas exchange and prevent the transudation of fluid into the pulmonary interstitium. 2. **Why Other Options are Incorrect:** * **Option B (10-14 mm Hg):** While overlapping with the upper limit of normal, this range is too narrow and trends toward the higher side of physiological limits. * **Option C (12-18 mm Hg):** This represents "borderline" elevation. Pressures in this range often indicate early left ventricular dysfunction or fluid overload. * **Option D (18-25 mm Hg):** This is significantly elevated. PCWP >18 mm Hg is a hallmark of **Cardiogenic Pulmonary Edema**. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard:** PCWP is the gold standard for differentiating cardiogenic pulmonary edema (PCWP >18 mm Hg) from Non-Cardiogenic Pulmonary Edema/ARDS (PCWP Venous > Alveolar pressure). * **Mitral Stenosis:** In cases of mitral stenosis, PCWP is elevated despite normal left ventricular function.

Q: Brain natriuretic peptide is degraded by which enzyme?

Neutral endopeptidase. **Explanation:** **1. Why Neutral Endopeptidase (NEP) is correct:** Brain Natriuretic Peptide (BNP), along with Atrial Natriuretic Peptide (ANP) and C-type Natriuretic Peptide (CNP), belongs to a family of hormones that regulate blood pressure and fluid balance. These peptides are primarily degraded by **Neutral Endopeptidase (NEP)**, also known as **Neprilysin**. NEP is a zinc-dependent metalloendopeptidase found in high concentrations in the renal proximal tubules and vascular endothelium. It cleaves the natriuretic peptides, thereby terminating their vasodilatory and diuretic actions. **2. Why the other options are incorrect:** * **Elastase:** This is a protease that breaks down elastin in connective tissue. While relevant in conditions like emphysema (Alpha-1 antitrypsin deficiency), it plays no role in BNP metabolism. * **Collagenase:** This enzyme breaks the peptide bonds in collagen. It is involved in tissue remodeling and wound healing, not the degradation of circulating hormones. * **Ompatrilat:** This is not an enzyme; it is a **drug** (a vasopeptidase inhibitor). It inhibits both NEP and ACE. While it affects BNP levels by preventing its degradation, it is the *inhibitor*, not the *degrading enzyme* itself. **Clinical Pearls for NEET-PG:** * **Sacubitril:** A potent Neprilysin inhibitor used in the treatment of Heart Failure (combined with Valsartan as ARNI). It increases BNP levels, providing therapeutic vasodilation and natriuresis. * **Diagnostic Note:** Because Sacubitril increases BNP levels, **NT-proBNP** is used instead of BNP to monitor heart failure patients on this medication, as NT-proBNP is not a substrate for Neprilysin. * **Clearance:** Natriuretic peptides are also removed from circulation via **Natriuretic Peptide Receptor-C (NPR-C)** through receptor-mediated endocytosis.

Q: Where does the slowest conduction velocity occur?

A.V. node. The conduction velocity of the cardiac impulse varies significantly across different parts of the heart to ensure efficient mechanical function. ### **1. Why the A.V. Node is the Correct Answer** The **A.V. node** has the slowest conduction velocity in the heart (approximately **0.01 to 0.05 m/s**). This physiological slowness is known as **A.V. nodal delay** (approx. 0.1 seconds). * **Mechanism:** It is caused by a smaller fiber diameter, fewer gap junctions between cells, and a less negative resting membrane potential. * **Purpose:** This delay allows the atria sufficient time to contract and empty blood into the ventricles before ventricular contraction begins, ensuring optimal stroke volume. ### **2. Analysis of Incorrect Options** * **A. Atrial Muscle:** Conducts at about **0.3 m/s**. While slower than Purkinje fibers, it is significantly faster than the A.V. node. * **C. Purkinje Fibers:** This is the **fastest** conducting tissue in the heart (approx. **2.0 to 4.0 m/s**). High velocity is essential here to ensure near-simultaneous contraction of both ventricles. * **D. Ventricular Muscle:** Conducts at about **0.3 to 0.5 m/s**, similar to atrial muscle. ### **3. High-Yield NEET-PG Facts** * **Mnemonic for Conduction Velocity (Fastest to Slowest):** **"He Purks At Venture Avenue"** * **Purk**inje fibers (Fastest: 4 m/s) * **At**ria (1 m/s) * **Ventu**re (Ventricles: 0.3–0.5 m/s) * **Avenue** (AV node: Slowest: 0.01–0.05 m/s) * **Clinical Pearl:** Drugs like Beta-blockers and Calcium Channel Blockers (Verapamil/Diltiazem) further slow A.V. nodal conduction, which is why they are used to control heart rate in atrial fibrillation. * **SA Node:** While the SA node is the pacemaker, its conduction velocity is also slow (0.05 m/s), but the AV node remains the slowest point in the entire system.

Q: Which of the following is true regarding blood pressure measurement using a sphygmomanometer?

May be falsely high in obese patients. **Explanation:** The accuracy of blood pressure (BP) measurement via a sphygmomanometer depends heavily on the **cuff size** relative to the **arm circumference**. **1. Why Option C is Correct:** In obese patients, the arm circumference is larger. If a standard-sized cuff is used, the pressure applied by the inflating bladder is not transmitted efficiently to the underlying artery. Consequently, the cuff must be inflated to a much higher pressure than the actual intra-arterial pressure to occlude the artery, leading to a **falsely high (overestimated)** reading. This is often referred to as "cuff hypertension." **2. Analysis of Incorrect Options:** * **Option A:** A **narrow cuff** requires higher inflation pressure to compress the artery, leading to a **falsely high** reading, not low. (Mnemonic: Narrow = High; Wide = Low). * **Option B:** In patients with **stiffened/calcified arteries** (e.g., elderly or diabetics), the vessel wall resists compression. This requires higher cuff pressure to collapse the artery, resulting in a **falsely high** reading (Pseudohypertension). * **Option D:** A sphygmomanometer provides **indirect** measurements of Systolic (Phase I Korotkoff) and Diastolic (Phase V Korotkoff) pressures. Mean Arterial Pressure (MAP) is then calculated using the formula: $MAP = DBP + 1/3 (Pulse\ Pressure)$. **Clinical Pearls for NEET-PG:** * **Ideal Cuff Dimensions:** The bladder length should be **80%** and the width should be **40%** of the arm circumference. * **Korotkoff Sounds:** These are produced by **turbulent blood flow** through a partially occluded artery. * **Oscillometric Method:** Most automated BP monitors use this to measure oscillations and then *calculate* systolic and diastolic values using algorithms.

Question 1

Which of the following represents the QT interval on an electrocardiogram?

Accepted Answer

The interval from the beginning of ventricular depolarization to the end of ventricular repolarization.

Answer

The interval from the beginning of atrial depolarization to the beginning of ventricular repolarization.

Answer

The interval from the beginning of atrial repolarization to the beginning of ventricular depolarization.

Answer

The duration of atrial depolarization.

Question 2

Which of the following statements regarding nitric oxide is FALSE?

Accepted Answer

Acts by increasing cyclic GMP levels

Answer

Derived from endothelium

Answer

Vasodilator

Answer

Derived from arginine

Question 3

The dicrotic notch on an arterial pressure waveform corresponds to which event?

Accepted Answer

Closure of the aortic and pulmonic valves

Answer

Closure of the atrioventricular valves

Answer

Opening of the atrioventricular valves

Answer

Opening of the aortic and pulmonic valves

Question 4

What causes the dicrotic notch?

Accepted Answer

Closure of the atrioventricular valves

Answer

Closure of the mitral valve

Answer

Closure of the pulmonary valve

Answer

Closure of the tricuspid valve

Question 5

What is the normal Pulmonary Capillary Wedge Pressure (PCWP)?

Accepted Answer

6-12 mm Hg

Answer

10-14 mm Hg

Answer

12-18 mm Hg

Answer

18-25 mm Hg

Question 6

What is the primary function of phospholamban in cardiac muscle regulation?

Accepted Answer

To inhibit the sequestration of calcium into the sarcoplasmic reticulum.

Answer

To increase the interaction of calcium with myofilaments.

Answer

To promote the sequestration of calcium by mitochondria.

Answer

To activate the Na+/Ca2+ exchanger.

Question 7

Brain natriuretic peptide is degraded by which enzyme?

Accepted Answer

Neutral endopeptidase

Answer

Elastase

Answer

Collagenase

Answer

Ompatrilat

Question 8

Where does the slowest conduction velocity occur?

Accepted Answer

A.V. node

Answer

Atrial muscle

Answer

Purkinje fibre

Answer

Ventricular muscles

Question 9

Which of the following is true regarding blood pressure measurement using a sphygmomanometer?

Accepted Answer

May be falsely high in obese patients

Answer

May be falsely low with too narrow a cuff

Answer

May be falsely low in patients with badly stiffened arteries

Answer

Gives a direct reading of mean arterial pressure

Question 10

Coronary blood flow is increased by all of the following except?

Accepted Answer

Beta adrenergic blockade

Answer

A decrease in arterial PO2

Answer

An increase in arterial PCO2

Answer

Vagal stimulation

Cardiovascular System — MCQs

Cardiovascular System — MCQs

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