Cardiovascular System Practice Questions

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: 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 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 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: 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: 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: 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: 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

Q: Which of the following does NOT significantly contribute to the regulation of cerebral blood flow?

Potassium ions. ***Potassium ions*** - While potassium channels play a role in vascular smooth muscle function, extracellular **potassium ion concentration** does not significantly regulate overall cerebral blood flow within physiological ranges. - Changes in systemic potassium levels typically have more pronounced effects on cardiac and neuromuscular function compared to direct, significant regulation of cerebral vasculature. *Arterial PCO2* - **Arterial PCO2** is a potent regulator of cerebral blood flow; an increase in PCO2 leads to **vasodilation** and increased cerebral blood flow, while a decrease causes vasoconstriction. - This effect is mediated by changes in brain extracellular pH, which influences the tone of cerebral arterioles. *Blood pressure* - **Cerebral autoregulation** maintains stable cerebral blood flow despite changes in mean arterial blood pressure between approximately 60 and 150 mmHg. - Outside this range, very high or low **blood pressure** directly influences cerebral perfusion, making it a critical factor in cerebral blood flow regulation. *None of the options* - This option is incorrect because **potassium ions** do qualify as a factor that does NOT significantly contribute to cerebral blood flow regulation, making it the correct answer to this question.

Question 1

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 2

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 3

What is the resting membrane potential in ventricular cardiac muscle?

Accepted Answer

-90 mV

Answer

-70 mV

Answer

+70 mV

Answer

+90 mV

Question 4

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 5

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 6

S2 is associated with ?

Accepted Answer

Closure of semilunar valves

Answer

Rapid ventricular filling

Answer

Atrial contraction

Answer

Closure of AV valves

Question 7

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

Accepted Answer

Glutamate

Answer

Glycine

Answer

Norepinephrine

Answer

Serotonin

Question 8

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 9

Where is the highest oxygen concentration present in fetal circulation

Accepted Answer

IVC

Answer

SVC

Answer

Right ventricle

Answer

Aorta

Question 10

Which of the following does NOT significantly contribute to the regulation of cerebral blood flow?

Accepted Answer

Potassium ions

Answer

Arterial PCO2

Answer

Blood pressure

Answer

None of the options

Cardiovascular System — MCQs

Cardiovascular System — MCQs

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