Breathing and Exchange of Gases
Test 3

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following statements about respiratory disorders is correct?

Emphysema is caused by bacterial infection of the lungs.
Asthma involves inflammation of the bronchi and bronchioles.
Pneumonia results from excessive dust accumulation in the lungs.
Silicosis is a genetic disorder affecting alveoli.
2

Asthma is a condition where bronchi and bronchioles become inflamed, leading to difficulty in breathing.

Which condition is caused by bacterial or viral infection leading to inflammation of alveoli?

Emphysema
Asthma
Pneumonia
Bronchitis
3

Pneumonia is an infection that causes inflammation and fluid accumulation in the alveoli, leading to difficulty in breathing.

Which of the following lung volumes includes the volume of air remaining in the lungs after a forced expiration?

Vital Capacity
Inspiratory Reserve Volume
Expiratory Reserve Volume
Residual Volume
4

Residual Volume (RV) is the air that remains in the lungs even after a forceful expiration, preventing lung collapse.

Which component of blood is mainly responsible for buffering pH changes due to carbon dioxide transport?

Hemoglobin
Bicarbonate ions
Plasma proteins
Red blood cell enzymes
2

Bicarbonate ions (HCO₃⁻) play a major role in buffering pH changes caused by CO₂ transport in the blood.

Which factor increases the affinity of hemoglobin for oxygen?

High pCO₂
High temperature
Low H⁺ concentration
Both 2 and 3
3

Low H⁺ concentration (higher pH) increases hemoglobin's affinity for oxygen, favoring oxygen uptake in the lungs.

Which of the following is NOT a function of the pleural fluid?

Reduces friction during breathing
Maintains lung expansion
Facilitates gas exchange
Provides lubrication to the lungs
3

Pleural fluid reduces friction and helps maintain lung expansion but does not directly facilitate gas exchange.

What is the primary stimulus for breathing in a healthy individual?

Low oxygen levels
High carbon dioxide levels
High oxygen levels
Low nitrogen levels
2

High CO₂ levels stimulate the respiratory centers in the brain to regulate breathing rate.

Which of the following statements about the human respiratory system is correct?

The larynx prevents the entry of food into the trachea during swallowing.
The bronchioles are lined with cartilaginous rings for support.
Gas exchange occurs in the bronchioles.
The right lung has two lobes, while the left lung has three lobes.
1

The larynx contains the epiglottis, which prevents food from entering the trachea during swallowing.

Which of the following statements regarding pulmonary ventilation is incorrect?

Inspiration occurs when intrapulmonary pressure decreases below atmospheric pressure.
Expiration occurs when intrapulmonary pressure is lower than atmospheric pressure.
Diaphragm contraction increases thoracic cavity volume.
External intercostal muscle contraction lifts the ribs during inspiration.
2

Expiration occurs when intrapulmonary pressure is **higher** than atmospheric pressure, forcing air out of the lungs.

Which of the following statements regarding alveolar gas exchange is correct?

O₂ diffuses from the alveoli into the blood due to a lower pO₂ in the alveolar air.
CO₂ diffuses from blood into alveoli due to its lower solubility in plasma.
Alveoli are lined with a thin epithelial layer to facilitate gas diffusion.
Gas exchange in alveoli occurs by active transport.
3

Alveoli are lined with a thin squamous epithelial layer to facilitate efficient gas diffusion.

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