Terminal bronchioles belong to the conducting zone and do not take part in gas exchange.
Correct Answer
True
True. The conducting zone ends with the terminal bronchioles and only moves, warms, filters and humidifies air. Gas exchange begins in the respiratory zone, starting with the respiratory bronchioles.
Category: Conducting Zone
Question 2
Inhaled foreign objects lodge more often in the left main bronchus because it is more vertical.
Correct Answer
False
False. The right main bronchus is wider, shorter and more vertical than the left, so aspirated objects more often enter the right side.
Category: Conducting Zone
Question 3
Type I alveolar cells are thin squamous cells that make up most of the alveolar wall surface.
Correct Answer
True
True. Type I alveolar cells are extremely thin, which keeps the diffusion distance short. Together with the capillary endothelium and their fused basement membranes, they form the respiratory membrane.
Category: Alveoli and Membrane
Question 4
The vocal folds are located within the pharynx.
Correct Answer
False
False. The vocal folds are located in the larynx, where air passing between them makes them vibrate to produce sound. The pharynx is the throat passage that lies behind the nasal cavity, mouth and larynx.
Category: Conducting Zone
Question 5
The visceral pleura adheres directly to the surface of the lung.
Correct Answer
True
True. The visceral pleura covers the lung surface and dips into its fissures. The parietal pleura lines the thoracic wall, diaphragm and mediastinum, with the pleural cavity between them.
Category: Lungs and Pleura
Question 6
The hilum is the region on the lateral surface of the lung where the bronchi and vessels enter.
Correct Answer
False
False. The hilum is on the medial (mediastinal) surface of the lung. The main bronchus, pulmonary vessels, lymphatics and nerves enter and leave there.
Category: Lungs and Pleura
Question 7
During inspiration, the volume of the thoracic cavity increases and intra-alveolar pressure falls below atmospheric pressure.
Correct Answer
True
True. As the thoracic cavity enlarges, the lungs expand and the pressure inside the alveoli drops below atmospheric pressure. Air then flows in down the pressure gradient until the pressures equalize.
Category: Mechanics of Breathing
Question 8
Contraction of the internal intercostal muscles raises the rib cage during quiet inspiration.
Correct Answer
False
False. The external intercostals raise the rib cage during inspiration. The internal intercostals pull the ribs down and are used during forced expiration.
Category: Mechanics of Breathing
Question 9
In a poorly ventilated area of the lung, the pulmonary arterioles serving it constrict and send blood to better ventilated areas.
Correct Answer
True
True. This ventilation-perfusion coupling matches blood flow to airflow. Low oxygen in poorly ventilated alveoli causes local pulmonary arterioles to constrict, unlike systemic arterioles, which dilate in response to low oxygen.
Category: Gas Exchange
Question 10
Carbon dioxide is much less soluble in plasma than oxygen is.
Correct Answer
False
False. Carbon dioxide is far more soluble in plasma than oxygen. This high solubility lets it diffuse readily even though its partial pressure gradient is smaller than that of oxygen.
Category: Gas Exchange
Question 11
During internal respiration, oxygen diffuses from systemic capillary blood into the tissue cells.
Correct Answer
True
True. Internal respiration is gas exchange between systemic capillaries and tissues. Oxygen partial pressure is lower in the tissues, so oxygen moves into the cells while carbon dioxide moves into the blood.
Category: Gas Exchange
Question 12
Each hemoglobin molecule can bind a maximum of two oxygen molecules.
Correct Answer
False
False. Each hemoglobin molecule has four heme groups, each with an iron atom, so it can bind up to four oxygen molecules.
Category: Gas Transport
Question 13
Carbon monoxide binds hemoglobin with a much greater affinity than oxygen does.
Correct Answer
True
True. Carbon monoxide attaches to hemoglobin far more strongly than oxygen and is not easily released, so it blocks oxygen transport. This is why carbon monoxide poisoning is dangerous even at low concentrations.
Category: Gas Transport
Question 14
An increase in body temperature shifts the oxygen-hemoglobin dissociation curve to the left.
Correct Answer
False
False. A rise in temperature shifts the curve to the right, lowering the affinity of hemoglobin for oxygen. This helps warm, active tissues receive more oxygen.
Category: Gas Transport
Question 15
Deoxygenated blood can carry carbon dioxide more readily than oxygenated blood, a relationship called the Haldane effect.
Correct Answer
True
True. When hemoglobin has released its oxygen, it binds carbon dioxide and hydrogen ions more easily. This helps blood load carbon dioxide in the tissues and unload it in the lungs.
Category: Gas Transport
Question 16
The basic rhythm of breathing is generated mainly by centers in the cerebellum.
Correct Answer
False
False. The respiratory rhythm is generated by centers in the brainstem, in the medulla oblongata, with the pons helping to adjust it. The cerebellum coordinates movement.
Category: Control and Modifications
Question 17
Peripheral chemoreceptors in the aortic and carotid bodies can increase ventilation in response to a large drop in blood oxygen.
Correct Answer
True
True. Peripheral chemoreceptors sense blood oxygen, carbon dioxide and pH. A substantial fall in oxygen stimulates them to signal the brainstem to increase breathing.
Category: Control and Modifications
Question 18
Hyperventilation raises the level of carbon dioxide in the blood.
Correct Answer
False
False. Hyperventilation blows off carbon dioxide faster than it is produced, lowering blood carbon dioxide and raising blood pH.
Category: Control and Modifications
Question 19
The epithelial lining of the trachea, bronchi and lungs develops from embryonic endoderm.
Correct Answer
True
True. The lung bud grows out of the endodermal foregut, so the epithelium lining the lower airways and alveoli is endoderm. The surrounding cartilage, smooth muscle, connective tissue and blood vessels come from mesoderm.
Category: Development
Question 20
At high altitude, the percentage of oxygen in the air is much lower than at sea level.
Correct Answer
False
False. Air is still about 21 percent oxygen at high altitude. What falls is the total atmospheric pressure, so the partial pressure of oxygen is lower and less oxygen diffuses into the blood.
Category: Control and Modifications