Respiratory system Knowledge-Based Download PDF

Questions

1. 1.

   Which physiological change promotes the unloading of oxygen from hemoglobin at systemic tissues by shifting the oxygen-hemoglobin dissociation curve to the right?

   • A) An increase in blood pH
   • B) A decrease in local tissue temperature
   • C) An increase in the partial pressure of carbon dioxide
   • D) A decrease in 2,3-bisphosphoglycerate levels
2. 2.

   Under normal resting conditions, which physiological change serves as the primary chemical stimulus to increase the rate and depth of ventilation in a healthy human?

   • A) A moderate decrease in the arterial partial pressure of oxygen
   • B) A decrease in the concentration of hydrogen ions in the cerebrospinal fluid
   • C) An elevation in the percentage of hemoglobin oxygen saturation
   • D) An increase in the arterial partial pressure of carbon dioxide
3. 3.

   What is the primary physiological function of pulmonary surfactant produced by type II alveolar cells in the human lungs?

   • A) It increases airway resistance by stimulating the contraction of bronchial smooth muscle.
   • B) It lowers surface tension within the alveoli to prevent them from collapsing during expiration.
   • C) It actively transports oxygen molecules across the alveolar-capillary membrane into the bloodstream.
   • D) It traps foreign particles and pathogens so they can be swept toward the pharynx by cilia.
4. 4.

   In human blood, in which form is the majority of carbon dioxide transported from systemic tissues to the lungs?

   • A) As bicarbonate ions dissolved in the blood plasma
   • B) Bound directly to hemoglobin as carbaminohemoglobin
   • C) As dissolved carbon dioxide gas in the blood plasma
   • D) Combined with plasma proteins to form carbamino compounds
5. 5.

   During quiet inhalation in a healthy human, which physiological mechanism directly causes air to flow into the lungs?

   • A) Contraction of the diaphragm and external intercostal muscles increases thoracic volume, reducing intrapulmonary pressure below atmospheric pressure.
   • B) Relaxation of the diaphragm flattens the thoracic floor, elevating alveolar pressure above atmospheric pressure.
   • C) Contraction of the internal intercostal muscles raises the rib cage, compressing the lungs and generating a positive pressure gradient.
   • D) Elastic recoil of alveolar tissues expands pulmonary volume, drawing atmospheric gases down an active osmotic gradient.