Trachea divides into two right and left primary bronchi at the level of:

1. Seventh cervical vertebra

2. Third thoracic vertebra

3. Fifth thoracic vertebra

4. Seventh thoracic vertebra

Contraction of diaphragm:

Volume of air that will remain in the lungs after a normal expiration is about:

1. 1200 ml

2. 2300 ml

3. 4600 ml

4. 5800 ml

The partial pressure of oxygen is equal in

1. Atmospheric air and Alveoli

2. Alveoli and Oxygenated blood

3. Alveoli and Deoxygenated blood

4. Deoxygenated blood and Tissues

The solubility of carbon dioxide is about _____ times higher than that of oxygen across the respiratory membrane.

1. 20-25

2. 25-50

3. 125-150

4. 200-250

What amount of carbon dioxide is delivered by every 100 ml of deoxygenated blood to the alveoli?

1. 4 ml

2. 5 ml

3. 15 ml

4. 20 ml

A center that moderates the functions of the respiratory rhythm center is located in:

1. Dorsal medulla oblongata

2. Ventral medulla oblongata

3. Pons Varolii

4. Pre-central gyrus of the cerebrum

Premature infants may develop respiratory distress and can land up in respiratory failure sometimes needing an intensive care for such infants. This may be due to:

1. the sudden change from the uterine environment to the air

2. the incomplete development of the lung surface

3. inadequate production of surfactant

4. mutations in the genes involved in lung formation

What keeps the lungs inflated even during expiration?

1. The smooth muscles of the lung

2. The diaphragm and the intercostal muscles alone

3. The visceral pleurae and the changing volume of the lungs

4. Surface tension from pleural fluid and negative pressure in the pleural cavity

Oxygen is mainly transported as oxyhaemoglobin in the blood. Identify the correct statement regarding oxygen transport in blood:

1. During normal activity, a molecule of hemoglobin returning to the lungs carries one molecule of O₂

2. During conditions of acidosis, hemoglobin is able to carry oxygen more efficiently.

3. Increased BPG levels in the red blood cells enhance oxygen-carrying capacity.

4. A 50% oxygen saturation level of blood returning to the lungs might indicate an activity level higher than normal.