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

Human heart is myogenic and it is supplied with sympathetic and vagus nerve branches that are acceleratory  and inhibitory in nature respectively.Which one of the following statement is incorrect w.r.t the heart beat?

  1. In foetal heart the heart rate is $140-130$ beats per minutes

  2. Mental status such as depression and grief decrease heart rate
  3. An excess of $Ca^{++}$ ion decreases heart beat rate
  4. High levels of $Na^+$ and $K^+$ decreases the strength of contraction
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heartbeat rate is the number of the beating of the heart per minute.

  • It is found that in normal humans, the rate of heartbeat is about 70 - 72 times per minute but in feotus or babies it is found much higher about 140 - 130 times per minute or may even up to 160 per minute. 
  • At the time of mental disorders like depression, grief or sadness body releases stress hormone, these stress hormone tightens the blood vessels, thus increases the heart rate.
  • Calcium ions play a major role in cardiac activity as well in muscle contraction when they are present in high amount then causes a lower heartbeat.
  • Sodium-potassium pumps are the ion channels or proton pumps that regulate the activity of contraction in the heart muscles. Excess of these ions dilates the blood vessels, thus lowers the heart rate and strength of the contraction of the heart muscles.
So, the correct option is 'Mental status such as depression and grief decrease heart rate'.

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

Time interval between DUP and LUBB is ______ coincide with _____

  1. $0.3$ sec, ventricular systole
  2. $0.5$ sec, joint diastole and atrial systole
  3. $0.4$ sec, joint diastole
  4. $0.1$ sec, atrial systole
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

DUP (second heart sound, closure of semilunar valves) and LUBB (first heart sound, closure of AV valves) bound the cardiac cycle. The time interval between DUP and the next LUBB corresponds to joint diastole and atrial systole, lasting approximately 0.5 seconds in a standard 0.8-second cardiac cycle.

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

A moderate increase in the concentration of which of the following ions speeds up the heart rate and strengthens the heart beat?

  1. Na$^+$ ions
  2. Ca$^{2+}$ ions
  3. $K^+$ ions

  4. All of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Calcium ions play a crucial role in cardiac muscle contraction and excitation-contraction coupling. A moderate increase in extracellular calcium ion concentration increases the strength of heart contraction and can speed up the heart rate.

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

State whether the following statement is true or false. If false rewrite the correct form of the statement by changing the last word.
The sound produced when the atrioventricular valves close in the heart is called dub.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The sound produced by the closure of the atrioventricular valves is called lubb, not dub. Dub is produced by the closure of the semilunar valves, making the statement false.

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

What happen on heart beating if the parasym-pathetic nerve going towards heart is cut down?

  1. Increases

  2. Decreases

  3. Normal

  4. Stopped
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The parasympathetic nervous system (via the vagus nerve) acts to slow down the heart rate. If this nerve is cut, the inhibitory effect is removed, leading to an increase in heart rate.

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

The volume of blood pumped by heart in one minute is called?

  1. Heart rate

  2. Systole

  3. Cardiac output

  4. Diastoles
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Cardiac output is the blood volume pumped in a minute by the core. It is equivalent to the rate of heart multiplied by the quantity of the stroke. So if there are 70 beats per minute and with each heart beat 70 ml of blood is drawn, the power production is 4900 ml / minute. This value is typical of an average resting adult, although during intense practice, cardiac production can achieve up to 30 liters / minute.

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 semilunar valves

  1. Closure of the tricuspid and Biscuspid valves

  2. Closure of the tricuspid and biuspid valves

  3. Opening of the semilunar valves

  4. Opening of the eustachian valve
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The first heart sound which we hear is produced by the simultaneous closure of both the atrioventricular valves namely, the bicuspid (mitral) valve and the tricuspid valve.

It resembles the word "LUBB" and is produced due to the isometric contraction period and the earlier part of ejection period.

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

The volume of blood pumped by heart in one minute is called?

  1. Heart rate

  2. Systole

  3. Cardiac output

  4. Diastols
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Cardiac output is the blood volume pumped in a minute by the core. It is equivalent to the rate of heart multiplied by the quantity of the stroke. So if there are 70 beats per minute and with each heart beat 70 ml of blood is drawn, the power production is 4900 ml / minute. This value is typical of an average resting adult, although during intense practice, cardiac output can reach  upto 30 liters / minute.

So, the correct answer is 'Heart rate'

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

The heart rate is increased by

  1. An increase in the activity of the sympathetic nerves that supply the heart

  2. A decrease in the activity of the parasympathetic (vagus) system

  3. An increase in the level of adrenalin in the circulation

  4. All of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A special neural centre in the medulla oblangata can moderate the cardiac function through autonomic nervous system (ANS). Neural signals through the sympathetic nerves (part of ANS) can increase the rate of heart beat, the strength of ventricular contraction and thereby the cardiac output. On the other hand, parasympathetic neural signals (another component of ANS) decrease the rate of heart beat, speed of conduction of action potential and thereby the cardiac output. Adrenal medullary hormones (adrenaline, noradrenaline) can also increase the cardiac output.

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

Heart rate is accelerated by

  1. Cranial nerves and acetylcholine

  2. Sympathetic nerves and acetycholine

  3. Cranial nerves and adrenalin

  4. Sympathetic nerves and epinephrine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Normal activities of the heart are regulated intrinsically, i.e., auto regulated by specialised muscles (nodal tissue), hence, the heart is called myogenic. A special neural centre in the medulla oblangata can moderate the cardiac function through autonomic nervous system (ANS). Neural signals through the sympathetic nerves (part of ANS) can increase the rate of heart beat, the strength of ventricular contraction and thereby the cardiac output. On the other hand, parasympathetic neural signals (another component of ANS) decrease the rate of heart beat, speed of conduction of action potential and thereby the cardiac output. Adrenal medullary hormones can also increase the cardiac output. Epinephrine / adrenaline increases the heart rate.