Tag: cardiac cycle

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Questions Related to cardiac cycle

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

'Dup' sound is produced during closure of

  1. Semilunar valves

  2. Bicuspid valve

  3. Tricuspid valve

  4. Both B and C
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Two distinct sounds can be heard during heart beat with the help of stethoscope. These are 'lubb' and 'dup'.
  • 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.
So, the correct answer is 'Semilunar valves'.
Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The pulse rate can be measured in the 

  1. Veins of neck

  2. Veins of the wrist

  3. Pulmonary vein

  4. None of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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.

So, the correct answer is 'None of the above'.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Heart beat is heard on left side as

  1. Aorta is on left side

  2. Heart is on left side

  3. Ventricles are on left side

  4. Left ventricle is on left side.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The heart is located in the mediastinum, but the apex of the heart, which is formed by the left ventricle, is directed toward the left side of the chest, making the heartbeat more audible there.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Sympathetic nervous system

  1. Decreases heart beat

  2. Increases heart beat

  3. Not related to heart beat

  4. Controls heart beat.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The sympathetic nervous system is responsible for the fight or flight response. This response includes increasing the heart rate to prepare the body for physical activity.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The hormone that stimulates heart beat is

  1. Thyroxine

  2. Adrenaline

  3. Glucagon

  4. Gastrin.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Adrenaline (epinephrine) is the primary hormone released during stress that stimulates the heart to beat faster and with more force. Thyroxine also affects heart rate, but adrenaline is the classic stimulator for immediate heart rate increases.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Origin of heart beat and its conduction is represented by

  1. AV node $\rightarrow$ Bundle of His $\rightarrow$ SA node $\rightarrow$ Purkinje fibres
  2. SA node $\rightarrow$ Purkinje fibres $\rightarrow$ AV node $\rightarrow$ Bundle of His
  3. Purkinje fibres $\rightarrow$ AV node $\rightarrow$ SA node $\rightarrow$ Bundle of His
  4. SA node $\rightarrow$ AV node $\rightarrow$ Bundle of His $\rightarrow$ Purkinje fibres
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

  • 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.
So, the correct answer is 'SA node →→ AV node →→ Bundle of His →→ Purkinje fibres'.

Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

Typical 'lubb-dup' sounds heard in heart beat are due to

  1. Closing of bicuspid and tricuspid valves

  2. Closing of semilunar valves

  3. Blood under pressure through aorta

  4. Closure of bicuspid-tricuspid valves followed by semilunar valves
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
Heart produces two distinct sounds that can be heard with the help of stethoscope. These are 'lubb' and 'dup'.
  • 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).
So, the correct answer is 'Closure of bicuspid-tricuspid valves followed by semilunar valves'.
Multiple choice biology transportation in plants and circulation in animals heart beat cardiac cycle heart, blood vessels and cardiac cycle

The first heart sound is

  1. Lubb during closure of semilunar valves

  2. Dupp during closure of semilunar valves

  3. Lubb during closure of atrioventricular valves

  4. Dupp during closure of atrioventricular valves
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
When the heart beats, it produces sounds that can be heard by stethoscope. There are four heart sounds which are designated as S1, S2, S3 and S4.
  • 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.
So, the correct answer is 'Lubb during closure of atrioventricular valves'.