Tag: cardiac cycle
Questions Related to cardiac cycle
'Dup' sound is produced during closure of
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Semilunar valves
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Bicuspid valve
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Tricuspid valve
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Both B and C
- Lubb is the first sound which has a low pitch and produced by the closure of tricuspid and bicuspid valves (collectively called atrioventricular valves) at the beginning of ventricular systole.
- Dup is the second sound which is sharp and has a high pitch. It is produced by closure of semilunar valves by the end of ventricular systole.
The pulse rate can be measured in the
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Veins of neck
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Veins of the wrist
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Pulmonary vein
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None of the above
This sequential event in the heart which is cyclically repeated is called the cardiac cycle. Each cardiac cycle consists of systole and diastole of both the atria and ventricles. Each cardiac cycle represents one heartbeat. The normal heart rate is about 72 beats per minute. The heart rate is same as pulse rate because the pumping action of the heart causes an increase in blood pressure in arteries. Hence pulse rate can be measured in the arteries of the neck and arteries of the wrist.
Heart beat is heard on left side as
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Aorta is on left side
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Heart is on left side
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Ventricles are on left side
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Left ventricle is on left side.
Sympathetic nervous system
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Decreases heart beat
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Increases heart beat
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Not related to heart beat
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Controls heart beat.
The hormone that stimulates heart beat is
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Thyroxine
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Adrenaline
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Glucagon
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Gastrin.
Heart beats originate from
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Left atrium
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Right ventricle
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Cardiac muscles
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Pace maker.
Which one regulates heart beat?
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Purkinje fibres
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Cardiac branch of vagus nerve
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SA node
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AV node.
Origin of heart beat and its conduction is represented by
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AV node $\rightarrow$ Bundle of His $\rightarrow$ SA node $\rightarrow$ Purkinje fibres
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SA node $\rightarrow$ Purkinje fibres $\rightarrow$ AV node $\rightarrow$ Bundle of His
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Purkinje fibres $\rightarrow$ AV node $\rightarrow$ SA node $\rightarrow$ Bundle of His
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SA node $\rightarrow$ AV node $\rightarrow$ Bundle of His $\rightarrow$ Purkinje fibres
- The impulse for heart beat is originated in SA node. It is known as the pace maker of heart and situated in upper right corner of right atrium.
- The electrical impulses generated by SA node are conducted to Atrio Ventricular or AV node.
- From the AV node, the impulses are transmitted to AV bundle, known as bundle of His which convey the impulses of contraction to the apex of myocardium.
- The impulses cause the Purkinje fibres to sweep upwards and outwards which results in pumping of blood into aorta and pulmonary artery.
- So, the correct sequence of propagation of cardiac impulse is SA node, AV node, Bundle of His, Purkinje fibres.
Typical 'lubb-dup' sounds heard in heart beat are due to
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Closing of bicuspid and tricuspid valves
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Closing of semilunar valves
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Blood under pressure through aorta
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Closure of bicuspid-tricuspid valves followed by semilunar valves
- Lubb is the first sound which has a low pitch and produced by the closure of tricuspid and bicuspid valves (collectively called atrioventricular valves) at the beginning of ventricular systole.
- Dup is the second sound which is sharp and has a high pitch. It is produced by closure of semilunar valves by the end of ventricular systole and beginning of ventricular diastole).
The first heart sound is
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Lubb during closure of semilunar valves
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Dupp during closure of semilunar valves
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Lubb during closure of atrioventricular valves
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Dupp during closure of atrioventricular valves
- S1: It is the first sound 'lubb'. It has slow pitch and produced by closure of atrioventricular valves at the beginning of ventricular systole.
- S2: It is the second sound 'dup'. It is sharper and has high pitch. It is produced by closure of semilunar valves by the end of ventricular systole.
- S3 and S4 are usually faint and may not be audible. S3 is produced during ventricular filling of heart and S4 is produced during atrial systole.