Examine these statements regarding Ventricular Diastole and valve closures:
(i) Ventricular relaxation leads to a fall in ventricular pressure. (ii) The fall in ventricular pressure causes the immediate opening of semilunar valves. (iii) Closure of semilunar valves prevents backflow of blood into ventricles and corresponds to the 'dub' sound. (iv) Further decline in ventricular pressure allows tricuspid and bicuspid valves to be pushed open by atrial pressure.
Explanation: Statements (i), (iii), and (iv) are correct. Statement (ii) is incorrect because a fall in ventricular pressure causes the semilunar valves to close, not open.
Question 42 of 100
📘 CLASS XI
Consider these statements regarding Stroke Volume and Cardiac Output:
(i) Stroke volume is the volume of blood pumped out by each ventricle during a single cardiac cycle (approximately 70 mL). (ii) Cardiac output is calculated by multiplying the stroke volume by the heart rate. (iii) In a healthy individual, the cardiac output averages about 5000 mL (5 litres) per minute. (iv) The cardiac output of an athlete is equal to that of an ordinary man.
Explanation: Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because athletes generally have a greater stroke volume and can achieve a much higher cardiac output during activity.
Question 43 of 100
📘 CLASS XI
Study the statements regarding heart sounds produced during the cardiac cycle:
(i) The first heart sound is 'lub' and is associated with the closure of the tricuspid and bicuspid valves. (ii) The second heart sound is 'dub' and is associated with the closure of semilunar valves. (iii) Both heart sounds are produced during the peak of the ventricular systole phase. (iv) These sounds have high clinical diagnostic significance.
Explanation: Statements (i), (ii), and (iv) are correct. Statement (iii) is incorrect because 'lub' occurs at the beginning of ventricular systole, whereas 'dub' occurs at the beginning of ventricular diastole.
Question 44 of 100
📘 CLASS XI
Read these statements regarding standard ECG connection leads:
(i) In a standard ECG, a patient is connected to the recording machine with three electrical leads. (ii) One lead is attached to each wrist, and one is attached to the right ankle. (iii) For a detailed evaluation of heart function, multiple leads are attached to the chest region. (iv) Electrocardiograph is the name of the graphical recording, while electrocardiogram is the machine used.
Explanation: Statements (i) and (iii) are correct. Statement (ii) is incorrect because the standard leads are attached to each wrist and the left ankle. Statement (iv) is incorrect because the electrocardiograph is the recording machine, while the electrocardiogram is the graphical record.
Question 45 of 100
📘 CLASS XI
Read the statements below regarding standard ECG waves and cardiac events:
(i) The P-wave represents the depolarization of the atria, which leads to atrial contraction. (ii) The QRS complex represents the depolarization of the ventricles, which initiates ventricular contraction. (iii) Ventricular contraction starts shortly after Q and marks the beginning of systole. (iv) The T-wave represents the repolarization of the ventricles, and the end of the T-wave marks the end of diastole.
Explanation: Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because the end of the T-wave marks the end of ventricular systole, not diastole.
Question 46 of 100
📘 CLASS XI
Read the statements regarding the tissue layers of blood vessels:
(i) Both arteries and veins consist of three layers of tissue: tunica intima, tunica media, and tunica externa. (ii) The tunica intima is the middle layer consisting of smooth muscle and elastic fibres. (iii) The tunica externa is the external layer made of fibrous connective tissue with collagen fibres. (iv) The tunica media is comparatively thinner in the veins than in the arteries.
Explanation: Statements (i), (iii), and (iv) are correct. Statement (ii) is incorrect because the tunica intima is the inner endothelial lining, whereas the tunica media is the middle layer composed of smooth muscle and elastic fibres.
Question 47 of 100
📘 CLASS XI
Examine these statements about the systemic and pulmonary pathways of double circulation:
(i) Pulmonary circulation involves pumping deoxygenated blood from the right ventricle to the lungs and returning oxygenated blood to the left atrium. (ii) Systemic circulation carries oxygenated blood from the left ventricle to tissues and returns deoxygenated blood to the right atrium. (iii) In both systems, a moderate mixing of oxygenated and deoxygenated blood occurs within the ventricles. (iv) The systemic circulation provides nutrients, oxygen, and other substances to tissues and removes carbon dioxide and wastes.
Explanation: Statements (i), (ii), and (iv) are correct. Statement (iii) is incorrect because in mammals and birds, oxygenated and deoxygenated blood remain completely separated due to the four-chambered heart.
Question 48 of 100
📘 CLASS XI
Review these statements about the neural regulation of cardiac activity:
(i) A special neural center in the medulla oblongata moderates cardiac functions through the autonomic nervous system. (ii) Sympathetic neural signals increase the heart rate, strength of ventricular contraction, and cardiac output. (iii) Parasympathetic neural signals decrease the heart rate, speed of action potential conduction, and cardiac output. (iv) Adrenal medullary hormones act to decrease overall cardiac output.
Explanation: Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because adrenal medullary hormones increase heart rate, force of contraction, and cardiac output.
Question 49 of 100
📘 CLASS XI
Read the statements below regarding Hypertension and Coronary Artery Disease:
(i) Hypertension is diagnosed when repeated checks show a blood pressure of 140/90 mm Hg or higher. (ii) In a 120/80 mm Hg blood pressure, 120 represents pumping (systolic) pressure and 80 represents resting (diastolic) pressure. (iii) Coronary Artery Disease (CAD) is also known as atherosclerosis. (iv) CAD makes the lumen of arteries narrower due to deposits of calcium and potassium only.
Explanation: Statements (i), (ii), and (iii) are correct. Statement (iv) is incorrect because atherosclerosis results from deposits of calcium, fat, cholesterol, and fibrous tissues, not potassium alone.
Question 50 of 100
📘 CLASS XI
Analyze these statements about Angina and Heart Failure:
(i) Angina pectoris is characterized by acute chest pain when insufficient oxygen reaches the heart muscle. (ii) Angina is a condition that occurs commonly only in children and young teenagers. (iii) Heart failure is the state of the heart when it is not pumping blood effectively enough to meet body needs. (iv) Heart failure is clinically identical to cardiac arrest and heart attack.
Explanation: Statements (i) and (iii) are correct. Statement (ii) is incorrect because angina is more common in middle-aged and elderly individuals. Statement (iv) is incorrect because heart failure, cardiac arrest, and heart attack are distinct clinical conditions.
