The mechanism of breathing depends on animal’s
1. habitat
2. level of organisation
3. Both A and B
4. Body segmentation

Which of the following is the part of the thoracic chamber
1. ribs and vertebral column
2. diaphragm
3. sternum
4. All of these

During inspiration there is __________pressure in the lungs with respect to atmospheric pressure.
(1)positive

(2)negative

(3)neither positive nor negative

(4)All of these

Pressure gradient between the lungs and atmosphere is maintained by
(1)diaphragm

(2)external intercostal muscles

(3)internal intercostal muscles

(4)All of these

Breathing is best described as

1. Utilisation of O₂ by the cells for catabolic reaction.

2. Transport of gases by the blood.

3. The movement of air into and out of the lungs.

4. Diffusion of gases across alveolar membrane

Inspiration occurs when intra-pulmonary pressure is

1. Higher than atmospheric pressure

2. Lower than atmospheric pressure.

3. Equal to atmospheric pressure.

4. Zero compared to atmospheric pressure.

Select the correct statement:

Contraction of diaphragm:

1. Increases the volume of the thoracic chamber in the antero-posterior axis

2. Increases the volume of the thoracic chamber in the dorso-ventral axis

3. Decreases the volume of the thoracic chamber in the antero-posterior axis

4. Decreases the volume of the thoracic chamber in the dorso-ventral axis

The movement of air into the lungs occurs due to a pressure gradient between the lungs and the atmosphere. So, inspiration occurs when/due to

1. Intra pulmonary is less than the atmospheric pressure

2. Increase in the volume of the thoracic chamber in the dorso-ventral axis

3. Contraction of external inter-costal muscles and phrenic muscles

4. All of these

During inspiration, the diaphragm

1. Contracts

2. Expands

3. Does not move

4. Relaxes