Cardiovascular System Practice Questions

Q: What is the normal capillary wedge pressure?

5-10 mm Hg. ***5-10 mm Hg*** - The **pulmonary capillary wedge pressure (PCWP)** or **pulmonary artery occlusion pressure (PAOP)** reflects the pressure in the left atrium and, indirectly, the left ventricular end-diastolic pressure (LVEDP). - A normal PCWP range is typically **4-12 mm Hg**, with 5-10 mm Hg being a common, healthy average. *0-2 mm Hg* - This value is **too low** to represent a normal PCWP. - A PCWP this low could indicate **hypovolemia** or severe vasodilation. *15-20 mm Hg* - This value is **elevated** and suggests **left ventricular dysfunction**, **heart failure**, or **volume overload**. - It would indicate increased pressure in the pulmonary circulation, potentially leading to **pulmonary congestion**. *20-30 mm Hg* - These values are **markedly elevated** and are highly indicative of significant **left ventricular failure** and **pulmonary edema**. - Such high pressures reflect severe compromise of the heart's pumping ability.

Q: What is the correct order of blood flow velocity in the human circulatory system?

Aorta > Artery > Arteriole > Vein > Venule > Capillary. ***Aorta > Artery > Arteriole > Vein > Venule > Capillary*** - The **aorta** has the highest blood flow velocity (~30 cm/s) as it directly receives blood from the left ventricle - Blood velocity **progressively decreases** through arteries and arterioles as total cross-sectional area increases - **Capillaries have the LOWEST velocity** (~0.03 cm/s) due to their enormous total cross-sectional area (~2500 cm²), allowing optimal time for gas and nutrient exchange - Velocity **increases again** in venules and veins as vessels converge and total cross-sectional area decreases - The key principle: velocity is **inversely proportional** to total cross-sectional area of vessels *Vena cava > Aorta > Vein > Artery > Venule > Arteriole* - This sequence incorrectly places vena cava first when the **aorta has higher velocity** than vena cava - The mixed ordering doesn't follow the anatomical flow pathway *Aorta > Artery > Vena cava > Vein > Arteriole > Venule* - The vena cava is misplaced in this sequence - **Arterioles should have lower velocity than arteries** but higher than capillaries, not placed after veins *Vena cava > Vein > Capillary > Arteriole > Aorta > Artery* - This sequence is completely reversed - **Aorta and arteries have the highest velocities**, not the lowest - Capillaries have the **lowest velocity**, not in the middle of the sequence

Q: S2 is associated with ?

Closure of semilunar valves. ***Closure of semilunar valves*** - The **second heart sound (S2)** is produced by the simultaneous **closure of the aortic and pulmonic valves** at the end of ventricular systole. - This event marks the beginning of **ventricular diastole** and prevents blood from flowing back into the ventricles from the aorta and pulmonary artery. *Rapid ventricular filling* - This phase occurs during **diastole**, after the semilunar valves have closed and the AV valves have opened. - It is associated with the **third heart sound (S3)** if present, which is a low-frequency sound of rapid ventricular distention. *Atrial contraction* - **Atrial contraction** occurs late in ventricular diastole and precedes the first heart sound (S1). - It is sometimes associated with the **fourth heart sound (S4)** in cases of decreased ventricular compliance. *Closure of AV valves* - The **closure of the atrioventricular (AV) valves** (mitral and tricuspid) produces the **first heart sound (S1)**. - This event marks the beginning of **ventricular systole** and prevents blood from flowing back into the atria from the ventricles.

Q: Major neurotransmitter in afferents to the nucleus tractus solitarius regulating the cardiovascular system?

Glutamate. ***Glutamate*** - **Glutamate** is the primary **excitatory neurotransmitter** in the central nervous system, and it plays a crucial role in the afferent nerve terminals of the **nucleus tractus solitarius (NTS)**. - Afferent signals from baroreceptors and chemoreceptors synapse in the NTS, where glutamate mediates the initial processing of these inputs to regulate **blood pressure** and heart rate. *Serotonin* - **Serotonin** (5-HT) has diverse roles in the brain, but its primary function in the **NTS** is not as the major fast-acting excitatory neurotransmitter for cardiovascular afferents. - While serotonin can modulate NTS activity, it is typically involved in slower, neuromodulatory effects rather than direct excitatory synaptic transmission from primary afferents. *Glycine* - **Glycine** is an important **inhibitory neurotransmitter**, primarily found in the spinal cord and brainstem. - It hyperpolarizes postsynaptic neurons, making them less likely to fire, which is the opposite effect of what is required for the initial excitatory transmission of cardiovascular afferent signals in the **NTS**. *Norepinephrine* - **Norepinephrine** is a **catecholamine neurotransmitter** involved in arousal, attention, and the fight-or-flight response. - While adrenergic neurons project to the **NTS** and can modulate its activity, norepinephrine is not the major neurotransmitter released by the primary afferent fibers that carry cardiovascular information to the NTS.

Q: What is the resting membrane potential in ventricular cardiac muscle?

-90 mV. ***-90 mV*** - The resting membrane potential in **ventricular muscle fibers** is approximately **-90 mV**, due to the high permeability to **potassium ions** at rest. - This **polarized state** is maintained by the **Na+/K+ ATPase pump**, which establishes ion gradients. *-70 mV* - A resting membrane potential of **-70 mV** is characteristic of **neurons** and skeletal muscle cells, not typical cardiac muscle cells. - This value is mainly maintained by the differential distribution of **sodium** and **potassium ions**. *+70 mV* - A potential of **+70 mV** represents a **depolarized state** far from the resting potential, indicative of an action potential peak. - This value would signify an influx of **positive ions**, primarily sodium, into the cell during activation. *+90 mV* - A potential of **+90 mV** is also a **depolarized state** and is not a resting membrane potential for any excitable cell type. - This value would represent a significant influx of positive charge, causing cell excitation.

Q: What is the average blood supply to the brain in ml/min?

750 ml/min. ***750 ml/min*** - The brain receives approximately **15% of the total cardiac output**, which translates to about 750 ml of blood per minute in a resting adult. - This flow rate is crucial for supplying the brain with adequate **oxygen and nutrients** to maintain its high metabolic demand. *1500 ml/min* - This value is significantly higher than the average blood flow to the brain and would represent an **abnormally increased cerebral blood flow**, potentially seen in specific pathological states. - The brain's metabolic needs, while substantial, do not typically require such a large volume of blood per minute under normal physiological conditions. *2000 ml/min* - This is an **extremely high value** for cerebral blood flow and is not consistent with normal physiological measurements for an adult brain. - Such a high flow rate could lead to **vascular issues** or is indicative of specific disease states rather than normal function. *250 ml/min* - This value represents a **significantly reduced cerebral blood flow**, which would be insufficient to meet the metabolic demands of the brain. - A persistent flow rate this low would likely result in **ischemia** and neuronal damage.

Q: Dicrotic notch is caused by:

Closure of aortic valve. ***Closure of aortic valve*** - The **dicrotic notch**, also known as the incisura, represents a brief increase in aortic pressure as blood rebounds against the **closed aortic valve**. - This event marks the end of systole and the beginning of diastole in the arterial pressure waveform. *Opening of mitral valve* - The opening of the mitral valve occurs during early diastole and is associated with the **rapid filling of the left ventricle**, not a notch on the arterial pressure waveform. - This event is more relevant to changes in left ventricular and left atrial pressures. *Opening of aortic valve* - The opening of the aortic valve marks the beginning of **ventricular ejection** (systole) and the rapid upstroke of the arterial pressure wave. - It does not cause a notch in the descending limb of the arterial pressure waveform. *Closure of mitral valve* - The closure of the mitral valve occurs at the beginning of **ventricular systole** and is associated with the first heart sound (S1). - This event is primarily reflected in left ventricular pressure changes and does not directly cause the dicrotic notch on the arterial pressure wave.

Q: The 'v' wave in JVP is due to:

Closure of tricuspid valve. ***Closure of tricuspid valve*** - The **'v' wave** in the JVP occurs during **ventricular systole** while the **tricuspid valve is closed**. - It represents the **passive filling of the right atrium** with venous return against the closed tricuspid valve, leading to a gradual rise in atrial pressure. - The peak of the 'v' wave occurs just before the tricuspid valve opens at the end of ventricular systole. - Note: The actual **closure** of the tricuspid valve produces the **'c' wave**, while the 'v' wave reflects the consequences of the valve remaining closed during atrial filling. *Right atrial contraction* - **Right atrial contraction** causes the **'a' wave** in the JVP, which is the first positive deflection in the cardiac cycle. - This wave reflects the increase in right atrial pressure as the atrium contracts to propel blood into the right ventricle during late diastole. *Isovolumetric relaxation* - **Isovolumetric relaxation** of the ventricle occurs after semilunar valve closure and before the tricuspid valve opens. - This phase is associated with the **'y' descent**, as ventricular pressure falls below atrial pressure allowing the tricuspid valve to open and blood to flow rapidly into the ventricle. *Right atrial relaxation* - **Right atrial relaxation** follows atrial contraction and contributes to the **'x' descent** in the JVP. - This decline reflects the pressure drop in the right atrium as it relaxes after contraction, coinciding with ventricular systole pulling the tricuspid annulus downward.

Q: What is the normal range for the QRS axis in degrees?

-30 to +110°. **-30 to +110°** - The **normal QRS axis** typically falls between -30° and +90° in most sources [1], but a slightly broader range up to +110° is often considered acceptable by some clinicians. - An axis between -30° and -90° indicates **left axis deviation** [1], and an axis greater than +90° (or +110°) indicates **right axis deviation** [1]. *+30 to 110°* - This range excludes a significant portion of the **normal QRS axis**, as it does not account for the normal variation that can extend into slightly negative degrees (e.g., -0° to -30°) [1]. - While +30° to +90° is a common normal axis, omitting the negative range makes this answer incomplete. *+110° to +150°* - This range represents **significant right axis deviation**, not a normal QRS axis [1]. - **Right axis deviation** can be indicative of conditions such as **right ventricular hypertrophy** or **pulmonary embolism**. *-110° to -150°* - This range indicates **extreme left axis deviation**, also known as **northwest axis**. - **Extreme axis deviations** are typically associated with severe cardiac pathologies, such as **ventricular tachycardia** or **hyperkalemia**, and are not within the normal physiological range.

Q: Where is the highest oxygen concentration present in fetal circulation

IVC. ***Correct: IVC (Inferior Vena Cava)*** - The IVC has the **highest oxygen concentration (~67% saturation)** among the vessels listed in fetal circulation - It receives **oxygenated blood from the placenta** via the umbilical vein, which continues as the ductus venosus and drains into the IVC - This well-oxygenated blood is preferentially shunted through the **foramen ovale** to the left atrium, then to the left ventricle and ascending aorta to supply the brain and heart *Incorrect: SVC (Superior Vena Cava)* - Carries **deoxygenated blood** from the upper body with oxygen saturation of only ~40% - Returns systemic venous blood without placental oxygenation *Incorrect: Right Ventricle* - Contains **mixed blood** from both SVC (deoxygenated) and IVC (oxygenated) - Has intermediate oxygen saturation (~52%) lower than the IVC alone *Incorrect: Aorta* - The **descending aorta** receives poorly oxygenated blood (~58%) from the ductus arteriosus - Even the ascending aorta (~62%) has slightly lower saturation than the IVC - The question asks for the highest concentration, which is the IVC before mixing occurs

Question 1

What is the normal capillary wedge pressure?

Accepted Answer

5-10 mm Hg

Answer

0-2 mm Hg

Answer

15-20 mm Hg

Answer

20-30 mm Hg

Question 2

What is the correct order of blood flow velocity in the human circulatory system?

Accepted Answer

Aorta > Artery > Arteriole > Vein > Venule > Capillary

Answer

Vena cava > Aorta > Vein > Artery > Venule > Arteriole

Answer

Aorta > Artery > Vena cava > Vein > Arteriole > Venule

Answer

Vena cava > Vein > Capillary > Arteriole > Aorta > Artery

Question 3

S2 is associated with ?

Accepted Answer

Closure of semilunar valves

Answer

Rapid ventricular filling

Answer

Atrial contraction

Answer

Closure of AV valves

Question 4

Major neurotransmitter in afferents to the nucleus tractus solitarius regulating the cardiovascular system?

Accepted Answer

Glutamate

Answer

Glycine

Answer

Norepinephrine

Answer

Serotonin

Question 5

What is the resting membrane potential in ventricular cardiac muscle?

Accepted Answer

-90 mV

Answer

-70 mV

Answer

+70 mV

Answer

+90 mV

Question 6

What is the average blood supply to the brain in ml/min?

Accepted Answer

750 ml/min

Answer

1500 ml/min

Answer

2000 ml/min

Answer

250 ml/min

Question 7

Dicrotic notch is caused by:

Accepted Answer

Closure of aortic valve

Answer

Opening of aortic valve

Answer

Opening of mitral valve

Answer

Closure of mitral valve

Question 8

The 'v' wave in JVP is due to:

Accepted Answer

Closure of tricuspid valve

Answer

Isovolumetric relaxation

Answer

Right atrial relaxation

Answer

Right atrial contraction

Question 9

What is the normal range for the QRS axis in degrees?

Accepted Answer

-30 to +110°

Answer

+30 to 110°

Answer

+110° to +150°

Answer

-110° to -150°

Question 10

Where is the highest oxygen concentration present in fetal circulation

Accepted Answer

IVC

Answer

SVC

Answer

Right ventricle

Answer

Aorta

Cardiovascular System — MCQs

Cardiovascular System — MCQs

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