Functional Anatomy of Cardiovascular System — MCQs
The following cardiac defects are characterized by ductus dependent blood flow except –
The ring is denoting the location of?
Which of the following structures in the heart are known for their rapid conduction of electrical impulses?
PR interval in ECG shows?
What is the primary function of the superior cervical ganglion?
What is the electrocardiographic finding associated with a left axis deviation of –30° to –60°?
The right coronary artery supplies blood to all of the following structures, except?
Which of the following murmurs increase with a Valsalva maneuver?
Which heart chamber has the thickest wall?
Which of the following is a true difference between gangliosides and cerebrosides?
Functional Anatomy of Cardiovascular System Indian Medical PG Practice Questions and MCQs
Question 1: The following cardiac defects are characterized by ductus dependent blood flow except –
- A. Truncus arteriosus (Correct Answer)
- B. Hypoplastic left heart syndrome
- C. Interrupted aortic arch
- D. Transposition of great arteries with intact septum
Explanation: ***Truncus arteriosus*** - **Truncus arteriosus** is a congenital heart defect where a single arterial trunk arises from the heart, supplying the systemic, pulmonary, and coronary circulations. - Blood mixing occurs **within the heart itself** at the level of the common truncal valve and ventricular septal defect (VSD), which is always present. - The ductus arteriosus is **not required** for survival because the truncal vessel directly supplies both the systemic and pulmonary circulations. - Therefore, truncus arteriosus is **NOT a ductus-dependent lesion**. *Transposition of great arteries with intact septum* - In **TGA with intact ventricular septum**, the aorta arises from the right ventricle and the pulmonary artery from the left ventricle, creating **parallel circulations**. - The patent ductus arteriosus (PDA) is **critical for mixing** oxygenated and deoxygenated blood, allowing survival until surgical correction. - This is a classic **ductus-dependent lesion** for mixing. *Hypoplastic left heart syndrome* - **HLHS** involves severe underdevelopment of the left ventricle, mitral valve, aortic valve, and ascending aorta. - The **PDA is essential** for providing systemic blood flow, as the right ventricle must supply both pulmonary and systemic circulations via the ductus. - This is a **ductus-dependent systemic circulation** - closure of the PDA is lethal. *Interrupted aortic arch* - **IAA** involves complete discontinuity of the aortic arch, preventing blood flow to the descending aorta. - The **PDA is critical** for perfusing the lower body and abdominal organs. - This is a **ductus-dependent systemic circulation**.
Question 2: The ring is denoting the location of?
- A. Pulmonary valve
- B. Tricuspid valve (Correct Answer)
- C. Mitral valve
- D. Aortic valve
Explanation: ***Tricuspid valve*** - The image likely displays a **cardiac outline** on an X-ray, and the ring points to the typical location of the **tricuspid valve** within the right side of the heart. - The tricuspid valve separates the **right atrium** from the **right ventricle**. *Pulmonary valve* - The pulmonary valve is located anterior and to the left of the tricuspid valve, separating the **right ventricle** from the **pulmonary artery**. - Its position is generally superior and more towards the midline compared to the ring's location. *Mitral valve* - The mitral valve is situated on the **left side of the heart**, between the **left atrium** and **left ventricle**. - Its location is distinctly different from the highlighted area. *Aortic valve* - The aortic valve is located between the **left ventricle** and the **aorta**, typically found superior and central in relation to the cardiac silhouette. - This position is away from the area indicated by the ring.
Question 3: Which of the following structures in the heart are known for their rapid conduction of electrical impulses?
- A. Sinoatrial (SA) node
- B. Atrioventricular (AV) node
- C. His bundle
- D. Purkinje fibers (Correct Answer)
Explanation: ***Correct: Purkinje fibers*** - **Purkinje fibers** have the **fastest conduction velocity** among all cardiac tissues, approximately **4 m/s** - These specialized myocardial fibers ensure **rapid and synchronized depolarization of the ventricles**, allowing for efficient and coordinated ventricular contraction - Their rapid conduction is essential for simultaneous contraction of ventricular myocardium from apex to base *Incorrect: Sinoatrial (SA) node* - The SA node is the natural **pacemaker** of the heart, initiating electrical impulses at a rate that determines heart rate - However, its conduction velocity is **very slow** (~0.05 m/s), much slower than Purkinje fibers - Its role is impulse generation, not rapid conduction *Incorrect: Atrioventricular (AV) node* - The AV node has the **slowest conduction velocity** in the heart (~0.05 m/s) - It **delays electrical impulses** from the atria to the ventricles (AV delay ~0.1 seconds) - This delay allows for **complete ventricular filling** before ventricular contraction begins *Incorrect: His bundle* - The bundle of His transmits impulses from the AV node to the bundle branches - While faster than the AV node (~1-1.5 m/s), it is still **significantly slower than Purkinje fibers** - Its conduction velocity is intermediate between the AV node and Purkinje fibers
Question 4: PR interval in ECG shows?
- A. Atrial depolarization and conduction delay (Correct Answer)
- B. Conduction through AV node
- C. Delay in ventricular depolarization
- D. Delay in ventricular repolarization
Explanation: ***Atrial depolarization and conduction delay*** - The **PR interval** is measured from the **beginning of the P wave** to the **beginning of the QRS complex**. - It represents the **complete time** for the electrical impulse to travel from the SA node through the atria, the AV node, the Bundle of His, and bundle branches until ventricular depolarization begins. - This includes two major components: 1. **Atrial depolarization** (represented by the P wave) 2. **Conduction delay** through the AV node and His-Purkinje system (the isoelectric segment after the P wave) - **Normal PR interval**: 0.12-0.20 seconds (120-200 ms) - The **AV nodal delay** is the longest component, allowing atrial contraction to complete before ventricular contraction begins. *Conduction through AV node* - While **AV nodal conduction** is an important component of the PR interval, this option is **incomplete**. - The PR interval begins with the **P wave** (atrial depolarization), which occurs before the impulse reaches the AV node. - Stating only "conduction through AV node" ignores the atrial depolarization component that is also part of the PR interval. *Delay in ventricular depolarization* - **Ventricular depolarization** is represented by the **QRS complex**, not the PR interval. - The PR interval *ends* when ventricular depolarization begins (start of QRS). *Delay in ventricular repolarization* - **Ventricular repolarization** is represented by the **T wave** on an ECG. - This occurs much later in the cardiac cycle and is not related to the PR interval.
Question 5: What is the primary function of the superior cervical ganglion?
- A. Is the largest cervical ganglion
- B. Supplies sympathetic fibers to the dilator pupillae muscle (Correct Answer)
- C. Deep petrosal nerve of pterygopalatine ganglion is derived from plexus around internal carotid artery
- D. Left superior cervical cardiac branch goes to deep cardiac plexus
Explanation: Supplies sympathetic fibers to the dilator pupillae muscle - The superior cervical ganglion is the primary source of postganglionic sympathetic fibers to the head and neck. - One of its key functions is providing sympathetic innervation to the dilator pupillae muscle [1] via the long ciliary nerves, causing mydriasis (pupil dilation) [2]. - This represents a clear physiological function of the ganglion in autonomic control of the eye. Is the largest cervical ganglion - While the superior cervical ganglion is indeed the largest of the three cervical sympathetic ganglia, this is an anatomical characteristic, not a function. - Size is a structural feature, not a physiological role. Left superior cervical cardiac branch goes to deep cardiac plexus - The superior cervical ganglion does contribute cardiac branches to the cardiac plexus for sympathetic innervation of the heart. - However, this describes an anatomical pathway rather than the primary function itself, and specifying "left" and "deep cardiac plexus" makes it overly specific rather than addressing overall function. Deep petrosal nerve of pterygopalatine ganglion is derived from plexus around internal carotid artery - The superior cervical ganglion does send postganglionic fibers forming a plexus around the internal carotid artery, which contributes to the deep petrosal nerve. - However, this is an anatomical derivation/pathway, not a functional description of what the ganglion does physiologically.
Question 6: What is the electrocardiographic finding associated with a left axis deviation of –30° to –60°?
- A. Left ventricular hypertrophy (Correct Answer)
- B. Right ventricular hypertrophy
- C. Aortic stenosis
- D. Left atrial enlargement.
Explanation: ***Left ventricular hypertrophy*** - A left axis deviation between **–30° and –60°** is a common finding in **left ventricular hypertrophy** due to the increased muscle mass prolonging depolarization towards the left [1]. - This condition is often indicated by other ECG changes such as increased **QRS voltage** in leads V5/V6 and V1/V2, along with **ST-T wave abnormalities** [1]. *Right ventricular hypertrophy* - This condition typically causes a **right axis deviation** (usually >+90°), not a left axis deviation, due to the increased electrical forces directed towards the right [1]. - ECG findings often include tall R waves in V1 and deep S waves in V6. *Aortic stenosis* - While **severe aortic stenosis** can cause left ventricular hypertrophy, aortic stenosis itself is not an ECG finding but an underlying valvular heart disease [2]. - The direct ECG manifestation would be signs of the resulting hypertrophy, not the stenosis itself [2]. *Left atrial enlargement* - Left atrial enlargement typically manifests on an ECG as a **broad and notched P wave** (P mitrale) in lead II or a prominent negative phase of the P wave in V1, indicative of delayed left atrial depolarization. - This is a distinct finding from axis deviation, which refers to the QRS complex.
Question 7: The right coronary artery supplies blood to all of the following structures, except?
- A. Posterior wall of left ventricle
- B. SA node
- C. Anterior 2/3 of ventricular septum (Correct Answer)
- D. AV node
Explanation: ***Anterior 2/3 of ventricular septum*** - The **anterior two-thirds of the interventricular septum** is primarily supplied by the **septal branches of the left anterior descending artery** (LAD) [1], a branch of the left coronary artery. - Therefore, the right coronary artery does not typically supply this region. *SA node* - The **SA node** (sinoatrial node) is the heart's natural pacemaker and receives its blood supply from the **right coronary artery** in about 60% of individuals. - Occlusion of the RCA can lead to symptomatic **bradycardia** or **SA node dysfunction**. *AV node* - The **AV node** (atrioventricular node), crucial for coordinating ventricular contraction, is supplied by the **right coronary artery** in approximately 90% of individuals [1]. - Infarcts in the RCA territory can manifest as various degrees of **heart block**. *Posterior wall of left ventricle* - The **posterior wall of the left ventricle** is predominantly supplied by the **posterior descending artery (PDA)**, which in about 80% of people, is a terminal branch of the **right coronary artery** [1]. - This supply is vital for the contractile function of the left ventricle's posterior aspect.
Question 8: Which of the following murmurs increase with a Valsalva maneuver?
- A. MR
- B. VSD
- C. AS
- D. Hypertrophic cardiomyopathy (Correct Answer)
Explanation: ***Hypertrophic cardiomyopathy*** - The Valsalva maneuver decreases **preload**, leading to a reduction in left ventricular volume and an **increased outflow tract obstruction**. - This increased obstruction accentuates the murmur of hypertrophic cardiomyopathy, making it louder. *MR* - Mitral regurgitation (MR) murmur typically **decreases** or remains unchanged with the Valsalva maneuver due to reduced **venous return** and thus reduced left ventricular preload. - A decrease in preload lessens the volume of blood being regurgitated from the left ventricle into the left atrium. *VSD* - The murmur of a ventricular septal defect (VSD) usually **decreases** during the Valsalva maneuver because of the reduction in **venous return** and consequent decrease in left-to-right shunting. - Decreased systemic vascular resistance relative to pulmonary resistance also plays a role, reducing the pressure gradient for shunting. *AS* - Aortic stenosis (AS) murmur generally **decreases** during the Valsalva maneuver due to decreased **left ventricular volume** and reduced transvalvular flow. - The reduction in preload lessens the blood ejected through the stenotic aortic valve, thereby reducing the intensity of the murmur.
Question 9: Which heart chamber has the thickest wall?
- A. Right atrium
- B. Left atrium
- C. Left ventricle (Correct Answer)
- D. Right ventricle
Explanation: ***Left ventricle*** - The left ventricle is responsible for pumping **oxygenated blood** to the entire systemic circulation, requiring significant force. - Its muscular wall is the **thickest** to generate the high pressures needed to overcome systemic vascular resistance [1]. *Right atrium* - The right atrium receives deoxygenated blood from the body and pumps it to the right ventricle, which is a **low-pressure circuit** [2]. - Its walls are relatively thin compared to the ventricles, as it only needs to provide a small "kick" to fill the right ventricle. *Left atrium* - The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle, operating under **low pressure**. - Its walls are thin, similar to the right atrium, as it does not need to generate high pressures. *Right ventricle* - The right ventricle pumps deoxygenated blood to the **pulmonary circulation**, which is a **low-pressure system** [1]. - While thicker than the atria, its wall is thinner than the left ventricle because it faces less resistance and pumps against lower pressures to the lungs.
Question 10: Which of the following is a true difference between gangliosides and cerebrosides?
- A. Specific carbohydrate composition
- B. Charge difference (Correct Answer)
- C. Location in the nervous system
- D. Presence of glucose
Explanation: ***Charge difference*** - **Gangliosides** contain **sialic acid (N-acetylneuraminic acid)** residues, which are negatively charged, making gangliosides **anionic**. - **Cerebrosides** are **neutral glycosphingolipids** as they lack charged sugar residues. *Specific carbohydrate composition* - While both have carbohydrate components, referring to "specific carbohydrate composition" as the *true difference* is too broad. Both have characteristic sugar groups, but the **presence of sialic acid** in gangliosides is the key differentiator in charge. - Cerebrosides typically contain a single sugar (either glucose or galactose), whereas gangliosides have a more complex oligosaccharide chain including sialic acid. *Presence of glucose* - Both cerebrosides (specifically **glucocerebrosides**) and gangliosides can contain **glucose** in their carbohydrate moieties. - This is not a distinguishing feature; the *type* and *arrangement* of sugars, particularly the presence of sialic acid, are more specific. *Location in the nervous system* - Both gangliosides and cerebrosides are abundant in the **nervous system**, particularly in cell membranes. - Their presence in the nervous system is a similarity, not a differentiating factor.
Want unlimited practice?
Get full access to all questions, explanations, and performance tracking.
Start For Free