Regarding inspiration in human breathing, consider the following statements:
I. Inspiration occurs when intra-pulmonary pressure is less than atmospheric pressure. II. Intra-pulmonary pressure during inspiration is negative with respect to atmospheric pressure. III. Inspiration occurs when intra-pulmonary pressure is higher than atmospheric pressure. IV. Air is forced out of the lungs during inspiration.
Statements I and II are correct: Inspiration occurs if intra-pulmonary pressure is less than atmospheric pressure (negative pressure), forcing outside air into lungs. Statements III and IV describe expiration, not inspiration.
Question 32 of 100
📘 CLASS XI
Regarding expiration in human breathing, analyze the following statements:
I. Expiration takes place when intra-pulmonary pressure is higher than atmospheric pressure. II. Expiration involves expulsion of alveolar air from lungs. III. Expiration occurs when intra-pulmonary pressure is negative relative to atmospheric pressure. IV. Intra-pulmonary pressure during expiration is lower than atmospheric pressure.
Statements I and II are correct: Expiration takes place when intra-pulmonary pressure is higher than atmospheric pressure, expelling air out. Statements III and IV are incorrect because negative/lower intra-pulmonary pressure leads to inspiration.
Question 33 of 100
📘 CLASS XI
Which muscles are primarily involved in generating pressure gradients for breathing?
I. Diaphragm II. External intercostal muscles III. Internal intercostal muscles IV. Cardiac muscle of left ventricle
Statements I, II, and III are correct: Diaphragm and specialised set of muscles (external and internal intercostals between ribs) help generate pressure gradients for breathing. Statement IV is incorrect as cardiac muscle pumps blood, not creating pulmonary pressure gradients.
Question 34 of 100
📘 CLASS XI
Consider the following statements regarding the role of diaphragm in inspiration:
I. Inspiration is initiated by the contraction of diaphragm. II. Contraction of diaphragm increases the volume of thoracic chamber in the antero-posterior axis. III. Contraction of diaphragm decreases the volume of thoracic chamber. IV. Relaxation of diaphragm increases thoracic volume in dorso-ventral axis.
Statements I and II are correct: Inspiration is initiated by contraction of diaphragm, which increases thoracic chamber volume in the antero-posterior axis. Statements III and IV are incorrect because contraction increases volume (antero-posterior), whereas relaxation decreases volume.
Question 35 of 100
📘 CLASS XI
Analyze the statements regarding external inter-costal muscles during inspiration:
I. Contraction of external inter-costal muscles lifts up the ribs and the sternum. II. Lifts up of ribs and sternum causes an increase in thoracic volume in the dorso-ventral axis. III. Contraction of external inter-costals decreases pulmonary volume. IV. It increases thoracic volume in the antero-posterior axis.
Statements I and II are correct: Contraction of external inter-costal muscles lifts ribs and sternum, increasing thoracic volume in the dorso-ventral axis. Statements III and IV are incorrect because it increases pulmonary volume, and diaphragm (not intercostals) increases volume in antero-posterior axis.
Question 36 of 100
📘 CLASS XI
Examine the overall mechanical changes leading to inspiration:
I. Overall increase in thoracic volume causes a similar increase in pulmonary volume. II. An increase in pulmonary volume decreases intra-pulmonary pressure. III. Intra-pulmonary pressure becomes less than atmospheric pressure. IV. Outside air is forced to move into the lungs.
All four statements (I, II, III, and IV) are correct: Increased thoracic volume -> increased pulmonary volume -> decreased intra-pulmonary pressure below atmospheric pressure -> air forced into lungs (inspiration).
Question 37 of 100
📘 CLASS XI
Consider the changes occurring during normal expiration:
I. Relaxation of the diaphragm returns it to its normal position. II. Relaxation of inter-costal muscles returns sternum to normal position. III. Thoracic volume and thereby pulmonary volume are reduced. IV. Intra-pulmonary pressure increases to slightly above atmospheric pressure, causing expulsion of air.
All four statements are correct: Relaxation of diaphragm and intercostals reduces thoracic/pulmonary volume, raising intra-pulmonary pressure above atmospheric pressure to expel air.
Question 38 of 100
📘 CLASS XI
Regarding additional breathing capability and breathing rate in humans, consider the statements:
I. Humans have the ability to increase the strength of inspiration and expiration with the help of additional muscles in the abdomen. II. On an average, a healthy human breathes 12-16 times/minute. III. Volume of air involved in breathing movements can be estimated using a spirometer. IV. A healthy human breathes 72-80 times/minute at rest.
Statements I, II, and III are correct: Abdominal muscles help increase breathing strength, healthy human breathes 12-16 times/min, and spirometer estimates breathing volumes. Statement IV is incorrect because 72-80 is resting heart rate, while breathing rate is 12-16 times/min.
Question 39 of 100
📘 CLASS XI
Examine the functional utility of a spirometer in clinical medicine:
I. Estimates the volume of air involved in breathing movements. II. Helps in clinical assessment of pulmonary functions. III. Measures partial pressure of O2 directly in arterial blood. IV. Directly measures cardiac output during exercise.
Statements I and II are correct: Spirometer estimates volume of air in breathing movements and helps in clinical assessment of pulmonary functions. Statements III and IV are incorrect because spirometer measures lung volumes/capacities, not arterial partial pressures or cardiac output.
Question 40 of 100
📘 CLASS XI
Which axis change corresponds correctly to which muscle action during inspiration?
I. Diaphragm contraction → Increases thoracic volume in Antero-posterior axis. II. External inter-costal contraction → Increases thoracic volume in Dorso-ventral axis. III. Diaphragm contraction → Increases thoracic volume in Dorso-ventral axis. IV. External inter-costal contraction → Increases thoracic volume in Antero-posterior axis.
Statements I and II are correct: Diaphragm contraction increases thoracic volume in antero-posterior axis, while external inter-costal contraction lifts ribs/sternum increasing volume in dorso-ventral axis. Statements III and IV invert these axes.
