Circulation | Biology | Target Mdcat 2025

Question 1

The SA node is located at the:

Lower dorsal region

Interventricular septum

Opening of the coronary sinus

Junction of the superior vena cava

Question 2

The primary pacemaker of the heart is the SA node because of its:

Neural control

Intrinsic rate of impulse generation

Location in the right atrium

Proximity to the AV node

Question 3

The delay of ~0.1 seconds for an impulse to travel from SA node to AV node ensures:

“Lub” sound generation

Atrial contraction completes before ventricles contract

Initiation of T-wave

Closing semilunar valves

Question 4

Total time for one complete cardiac cycle at rest is approximately:

0.3 sec

0.4 sec

0.8 sec

1.0 sec

Question 5

Chordae tendineae prevent:

Aortic valve prolapse

Inversion of AV valves during ventricular contraction

Conduction block in ventricles

Atrial dilation

Question 6

A newborn baby with cyanosis shortly after birth may have:

High blood pressure

Excess water

Efficient liver capillaries

An unclosed foramen ovale

Question 7

The AV node is also known as the:

Primary pacemaker

Purkinje activator

Artificial pacemaker

Secondary pacemaker

Question 8

The interval for conduction from SA node to AV node is approximately:

0.1 second

0.01 second

0.2 second

1.0 second

Question 9

Cardiac output increases in all of the following conditions EXCEPT:

Hypoxia

Exercise

Sleep

Pregnancy

Question 10

The closed, double-layered protective sac around the heart is:

Endocardium

Myocardium

Pericardium

Epicardium

Question 11

Papillary muscles function to:

Generate electrical impulses

Contract the atria

Separate the heart chambers

Anchor chordae tendineae to prevent valve inversion

Question 12

A left bundle branch block primarily affects:

Right ventricle depolarization

Left ventricle depolarization

AV nodal delay

Atrial contraction

Question 13

During isovolumetric contraction:

AV valves open, semilunar closed

Both AV and semilunar closed

AV closed, semilunar open

Both open

Question 14

The Frank–Starling law of the heart states:

Stroke volume rises with increased end-diastolic volume

Stroke volume falls with increased preload

Cardiac output is independent of venous return

Heart rate decreases with preload

Question 15

Aortic valve closure occurs at:

End of T-wave

Beginning of P-wave

Peak of QRS

Mid-PR interval

Question 16

The P-wave in ECG represents:

Atrial depolarization

Atrial repolarization

Ventricular depolarization

Ventricular repolarization

Question 17

ST-segment elevation most strongly indicates:

Hypocalcemia

Myocardial infarction

Hyperkalemia

AV nodal block

Question 18

In tachycardia (>150 bpm), which cardiac cycle phase is most reduced?

Atrial systole

Ventricular systole

Ventricular diastole

Isovolumetric contraction

Question 19

Ventricular filling is maximum during which phase?

Rapid filling phase

Diastasis

Atrial systole

Isovolumetric relaxation

Question 20

The 'a wave' in the jugular venous pulse corresponds to:

Atrial contraction

Atrial relaxation

Ventricular systole

Aortic valve closure

Question 21

Vasa vasorum are present in:

Tunica interna

Tunica media

Tunica externa

All layers

Question 22

Blood pressure is highest in:

Veins

Arteries

Capillaries

Venules

Question 23

Arterioles control blood pressure because:

They lack endothelium

They have thick tunica externa

They regulate resistance by changing diameter

They contain valves

Question 24

The artery supplying small intestine and proximal colon is the:

Celiac artery

Mesenteric artery

Iliac artery

Renal artery

Question 25

Pre-capillary sphincters control:

Entry of blood into venules

Entry of blood into capillary beds

Lymph flow

Heart rate