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.

During normal respiration, the ventral respiratory group located in the medulla oblongata:

1. Establishes the basic respiratory rhythm

2. Controls the switch off point of inspiration

3. Remains inactive

4. Excites chemosensitive zone neurons

Pneumotaxic centre which can moderate the functions of the respiratory rhythm centre is present at:

1. Pons region of brain

2. Thalamus

3. Spinal cord

4. Right cerebral hemisphere

The following statements refer to gas carriage by blood. Choose the correct statement:

1. After leaving the lungs, each litre of blood contains about 20 ml of oxygen.

2. Haemoglobin is half saturated with oxygen when the PO₂ is about 30 mm Hg

3. As the PCO₂ rises, the affinity of haemoglobin for oxygen is increased.

4. Each litre of arterial blood contains about 50 mL of carbon dioxide.

Study the spirograph and identify the correctly matched volumes from the codes given:

         TV        IRV     ERV       RV      VITAL CAPACITY
1.       A          c         B          D              E
2.       A          B        C          D               E
3.       B          A        C          D               E
4.       C          B        A          D               E

Fibrous connective tissue builds up in the lungs causing them not to inflate properly, and actually deflating them is called:

1. chronic bronchitis

2. emphysema

3. pulmonary fibrosis

4. asthma

The C-shaped cartilaginous rings around the trachea are open posteriorly to:

(1) allow for expansion of the esophagus during swallowing 

(2) allow the vocal cords to relax

(3) prevent food from entering the nasal cavity during swallowing

(4) prevent food from entering the trachea

The trachea is lined with

1. ciliated simple squamous epithelium
2. stratified squamous epithelium
3. pseudostratified ciliated columnar epithelium
4. pseudostratified squamous epithelium

When you hold your breath which of the following gas changes in blood would first lead to the urge to breathe?

(1) Falling O₂ concentration

(2) Rising CO₂ concentration

(3) Falling CO₂ concentration

(4) Rising CO₂ and falling O₂ concentration