Home
Class 12
BIOLOGY
Read the following statements : A. The...

Read the following statements :
A. The action potential generated by the SA node stimulates both ventricles to undergo simultaneous contraction.
B. The heart sound Lubb is associated with the closure of both semilunar valves.
C. The QRS complex in ECG represents the depolarization of the ventricles.
Select the appropriate option from the following :

A

A and B are correct , C is incorrect

B

A, B are incorrect and C is correct

C

Only B and C are correct

D

Only A is correct

Text Solution

AI Generated Solution

The correct Answer is:
To analyze the statements provided in the question, let's break down each statement step by step. ### Step-by-Step Solution: 1. **Statement A**: "The action potential generated by the SA node stimulates both ventricles to undergo simultaneous contraction." - The SA node, located in the right atrium, acts as the heart's pacemaker and generates an action potential that first stimulates the atria to contract (atrial systole). The signal then travels to the AV node, which subsequently sends impulses to the ventricles through the bundle of His and Purkinje fibers. Therefore, the ventricles do not contract simultaneously as a direct result of the SA node's action potential; they contract after the atria. - **Conclusion**: This statement is **incorrect**. 2. **Statement B**: "The heart sound Lubb is associated with the closure of both semilunar valves." - The heart sounds are produced by the closure of heart valves. The first heart sound, known as "Lubb," is actually caused by the closure of the atrioventricular valves (the bicuspid and tricuspid valves) at the beginning of ventricular contraction. The closure of the semilunar valves (aortic and pulmonary) produces the second heart sound, known as "Dubb." - **Conclusion**: This statement is **incorrect**. 3. **Statement C**: "The QRS complex in ECG represents the depolarization of the ventricles." - In an electrocardiogram (ECG), the QRS complex corresponds to the depolarization of the ventricles, which occurs just before the ventricles contract. This is a correct representation of the electrical activity in the heart. - **Conclusion**: This statement is **correct**. ### Final Evaluation: - **Statement A**: Incorrect - **Statement B**: Incorrect - **Statement C**: Correct ### Appropriate Option: Based on the analysis, the correct answer is that only Statement C is true. ---
Promotional Banner

Similar Questions

Explore conceptually related problems

Read the following statement and choose the correct option. A. The first heart sound (lub) is associated with the closure of both semilunar valves. The duration between the adjacent second heart sound and first heart sound is 0.3 seconds C. The cardiac output is the stroke volume multiplied by the number of heartbeats per minute.

Read the following statement (I - IV) I. The machine that is used to obtain ECG of a patient is called an electrocardiograph . II. The volume of blood pumped out by each ventricle per cardiac cycle is called the cardiac output . III. The second heart sound is associated with the opening of both semilunar values . IV. Hypertension is denoted by the ratio of systolic and diastolic pressure in mm of mercury pressure. How many statement (s) is/ are correct from the above ?

Which of the following statement is CORRECT ? I. Heart, the mesodermally derived organ, is situated in the thoracic cavity, in between the two lungs , slightly tilted to the left. II. During joint diastole , tricuspid and bicuspid valves are open and the semilunar values are closed. III. The first heart sound (lub) is associated with the closure of the tricuspid and biscuspid valves whereas the second heart sound (dub) is associated with the closure of the semilunar valves . IV. Neural signals through the sympathetic nerves can increases the rate of hearbeat, the strength of ventricular contraction and thereby the cardiac output.

Read the following statements (i) The nodal musculature of the heart has the ability to generate action potentials without any external stimuli. (ii) The AV node is located in the right ventricle close to the AV septum (iii) The stroke volume is the amount of blood pumped out by each ventricle per minute. Which of these are correct ?

Read the following statements (A-D) A. Coronary Artery Disease is also called atherosclerosis that affects the vessels that supply blood to the heart muscle. B. The electrocardiogram (ECG) on graph paper. During a cardiac cycle , the right ventricle pumps out about 70ml of oxygenated blood which is called stroke volume. D. The second heart sound is associated with the closure of the semilunar valves. How many statements from the above is / are incorrect ?

Read the following statements and select the correct option. A. Damage to chordae tendinae of semilunar valves in aorta causes back flow of blood in left ventricle. B. Closure of atrio-ventricular valves during ventricular systole generates first heart sound.

Read the following statements (A – D ) (A) QRS complex in ECG indicates ventricular depolarization. (B) The electrocardiograph machine is used to obtain Electrocardiogram a (ECG ) on graph paper . (C) During a cardiac cycle , the left ventricular pumps out about 70 ml is of Oxygenated blood which is called the cardiac output . (D) The second heart sound is associated with the closure of the semilunar valves . How many statements from the above is /are incorrect ?

Read the following statements carefully (i) In fishes, the heart pumps out deoxygenated blood which is oxygenated by the gills and supplied to the body parts from where deoxygenated blood is returned to the heart. (ii) The openings of the right and the left ventricle into pulmonary artery and aorta respectively are provided with the mitral valves. (iii) The nodal musculature has the ability to generate action potential without any external stimuli, i,e., it is autoexcitable. (iv) The T-wave of ECG represents depolarisation of the ventricles. Which of the above four statements are incorrect?

Read the following statements carefully and select correct choice from below: br (a) First heart sound lub is produced due to closure of atrioventricular valves, br (b) First heart sound is of longer duration than second heart sound dub.

Read the following statements about the internal structure of the human heart. I. Humans have a an auto - excitable , chambered , muscular and myogenic heat. II. The heart is mesodermal in origin and is present symmetrically between two lungs in the thoracic cavity. III. The opening between the right atrium and left ventricle is guarded by a tricuspid valve. IV. Only the sino - atrial node of the heart has hte ability to generate action potentials without any external stimuli. How many statement/s is/ are incorrect from the above ?