QCM : Fundamentals of Mammalian and Avian Respiratory Physiology — 12 questions

Explication

The respiratory system maintains blood pH balance by regulating carbon dioxide levels, which is a key function explicitly described as homeostatic regulation of body pH. The other options relate to other organ systems and are not functions of the respiratory system. Review: Functions and comparative anatomy of the respiratory system. Course evidence: "- **External respiration** : The movement of gases between the environment and the body’s cells, specifically the exchange of oxygen and carbon dioxide between the atmosphere and the blood. - **Homeostatic regulation of body pH** : The process by which the…"

Explication

The conducting system is specifically responsible for warming, humidifying, and filtering inspired air before it reaches the alveoli, as stated in the source. Gas exchange occurs in the alveoli, mucus production is a function of other cells, and volume regulation is controlled by respiratory muscles. Review: Structure and components of the mammalian respiratory apparatus. Course evidence: "**Conducting system** : The portion of the respiratory apparatus responsible for warming, humidifying, and filtering inspired air before it reaches the alveoli."

Explication

The source states that surface tension in alveoli increases the work of breathing because the fluid layer resists alveolar expansion, making it harder to inflate the lungs. Review: Mechanics, physical properties, and airway resistance in mammalian breathing. Course evidence: "Surface tension in alveoli increases work of breathing due to fluid layer between air and alveolar cells."

Explication

Parasympathetic stimulation via muscarinic receptors causes bronchoconstriction, increasing airway resistance. β2 receptors mediate bronchodilatation, while nicotinic and alpha-1 adrenergic receptors are not involved in this specific bronchoconstrictive response. Review: Airway resistance and neural control of bronchial smooth muscle. Course evidence: "Parasympathetic stimulation via muscarinic receptors causes bronchoconstriction, increasing airway resistance."

Explication

Tidal volume is defined as the amount of air inhaled or exhaled during normal breathing, distinguishing it from reserve volumes and residual volume. Review: Spirometry and lung volumes in different mammalian species. Course evidence: "- Tidal volume is the amount of air inhaled or exhaled during normal breathing."

Explication

Pulmonary arteries have thinner walls and less muscle compared to systemic arteries, which facilitates their role in carrying blood to the lungs for gas exchange. They do not contain valves and carry deoxygenated blood, unlike systemic arteries. Review: Pulmonary and bronchial circulation and blood flow regulation. Course evidence: "Pulmonary arteries have thinner walls and less muscle compared to systemic arteries."

Explication

Bird lungs separate ventilation and gas exchange via air sacs and parabronchi, with air capillaries providing a large surface area for gas exchange, which enhances efficiency. The other options describe mammalian or incorrect respiratory mechanisms not used by birds. Review: Comparative respiratory anatomy and ventilation in birds. Course evidence: "Bird lungs separate ventilation and gas exchange via air sacs and parabronchi, with air capillaries providing a large surface area for gas exchange."

Explication

The source clearly states that flow-through ventilation in fish gills functions to maintain continuous water movement over respiratory surfaces, which facilitates gas exchange. The other options describe different functions not attributed to flow-through ventilation in the source. Review: Gill structure and ventilation mechanisms in fishes. Course evidence: "Flow-through ventilation in fish gills maintains continuous water movement over respiratory surfaces."

Explication

The source states that hemoglobin affinity for oxygen is influenced by temperature, pH, CO2, and 2,3-BPG concentration. Glucose, sodium, and cholesterol concentrations are not mentioned as influencing hemoglobin affinity. Review: Gas exchange, oxygen transport, and hemoglobin affinity. Course evidence: "Hemoglobin affinity for oxygen is influenced by temperature, pH, CO2, and 2,3-BPG concentration."

Explication

The source states that carbon dioxide is transported in blood dissolved in plasma, bound to hemoglobin, and as bicarbonate ions, which are the main forms of CO2 transport. The other options are incorrect because they exclude these multiple forms or mention forms not supported by the source. Review: Carbon dioxide transport and diffusion in blood. Course evidence: "Carbon dioxide is transported in blood dissolved in plasma, bound to hemoglobin, and as bicarbonate ions. Carbonic anhydrase catalyzes the conversion between CO2 and bicarbonate, facilitating CO2 transport."

Explication

The source explicitly states that breathing is controlled by brainstem centers including the PRG, DRG, and VRG. The other options list brain regions not identified as primary neural centers for breathing control in the source. Review: Neural and chemical control mechanisms of breathing. Course evidence: "Breathing is controlled by brainstem centers including PRG, DRG, and VRG."

Explication

The source states that monoamine oxidase, located in endothelial cells, is responsible for removing and degrading serotonin in the lungs. The other enzymes listed have different functions not related to serotonin degradation in the lungs. Review: Nonrespiratory functions of the lungs including defense and metabolism. Course evidence: "Monoamine oxidase : An enzyme in endothelial cells responsible for removing and degrading serotonin in the lungs."