Respiratory System

Which of the following is the primary muscle involved in respiration?

• Diaphragm
• Pectoralis major
• Latissimus dorsi
• Biceps brachii

Answer explanation

The diaphragm is the main muscle involved in respiration. During inhalation, it contracts and moves downward, increasing the thoracic cavity's volume and allowing air to enter the lungs.

What is the main function of the alveoli in the lungs?

• Transport oxygen to tissues
• Produce mucus
• Exchange gases between air and blood
• Filter out dust and particles

Answer explanation

The alveoli are tiny air sacs in the lungs where gas exchange occurs. Oxygen from inhaled air passes through the alveolar walls into the blood, and carbon dioxide from the blood passes into the alveoli to be exhaled.

Which part of the brain controls the respiratory rate?

• Cerebellum
• Medulla oblongata
• Hypothalamus
• Thalamus

Answer explanation

The medulla oblongata is responsible for regulating the respiratory rate by sending signals to the respiratory muscles based on the body's oxygen and carbon dioxide levels.

During inhalation, the diaphragm:

• Contracts and moves upward
• Relaxes and moves upward
• Contracts and moves downward
• Relaxes and moves downward

Answer explanation

During inhalation, the diaphragm contracts and moves downward, creating a negative pressure within the thoracic cavity that draws air into the lungs.

What is the normal partial pressure of oxygen (PaO2) in arterial blood?

• 35-45 mmHg
• 50-70 mmHg
• 75-100 mmHg
• 90-120 mmHg

Answer explanation

The normal partial pressure of oxygen in arterial blood is 75-100 mmHg, indicating the amount of oxygen available for tissues.

What is the significance of surfactant in the lungs?

• Increases oxygen binding to hemoglobin
• Reduces surface tension in the alveoli
• Enhances mucus production
• Facilitates carbon dioxide removal

Answer explanation

Surfactant is a substance produced by Type II alveolar cells that reduces surface tension, preventing the alveoli from collapsing and ensuring efficient gas exchange.

Which structure prevents food from entering the respiratory tract?

• Epiglottis
• Trachea
• Bronchi
• Larynx

Answer explanation

The epiglottis is a flap of tissue that covers the opening of the trachea during swallowing, preventing food and liquids from entering the respiratory tract.

The trachea bifurcates into:

• Two bronchioles
• Two alveolar ducts
• Right and left bronchi
• Two pleural cavities

Answer explanation

The trachea divides into the right and left bronchi, which carry air to the right and left lungs, respectively.

What term describes the maximum amount of air that can be expelled from the lungs after maximum inhalation?

• Residual volume
• Tidal volume
• Vital capacity
• Inspiratory reserve volume

Answer explanation

Vital capacity is the maximum amount of air that can be exhaled after a maximum inhalation, indicating the total capacity of the lungs.

Which disease is characterized by chronic bronchitis and emphysema?

• Asthma
• Chronic obstructive pulmonary disease (COPD)
• Pneumonia
• Tuberculosis

Answer explanation

COPD is a chronic inflammatory lung disease that causes obstructed airflow from the lungs, primarily due to chronic bronchitis and emphysema.