Gas exchange Knowledge-Based Download PDF

Questions

1. 1.

   In human circulation and respiration, what is the primary form in which carbon dioxide is transported through the bloodstream to the lungs for gas exchange?

   • A) Bound to plasma albumin proteins
   • B) Dissolved directly as carbon dioxide gas in plasma
   • C) Precipitated as calcium carbonate crystals within red blood cells
   • D) As bicarbonate ions dissolved in the blood plasma
2. 2.

   Which statement correctly distinguishes external respiration from internal respiration in human physiology?

   • A) External respiration produces metabolic carbon dioxide via cellular respiration, whereas internal respiration vents carbon dioxide to the atmosphere.
   • B) External respiration relies on active transport carrier proteins, whereas internal respiration occurs exclusively via bulk liquid flow.
   • C) External respiration involves gas exchange between the alveoli and pulmonary blood, whereas internal respiration involves gas exchange between systemic capillaries and body tissues.
   • D) External respiration takes place during inhalation only, whereas internal respiration occurs exclusively during exhalation.
3. 3.

   What is the primary function of pulmonary surfactant in facilitating efficient gas exchange within human lungs?

   • A) It actively pumps carbon dioxide out of pulmonary capillary plasma into the alveolar airspace.
   • B) It lowers surface tension at the air-water interface of the alveoli, preventing alveolar collapse and preserving surface area.
   • C) It binds directly to oxygen molecules in the fluid lining of the alveoli to transport them across the epithelial layer.
   • D) It increases the thickness of the respiratory membrane to protect underlying pulmonary capillaries from atmospheric pressure.
4. 4.

   Which structural feature of the alveoli and pulmonary capillaries most directly minimizes the diffusion distance required for respiratory gas exchange?

   • A) A thick lining of pseudostratified ciliated columnar epithelial cells
   • B) An extremely thin respiratory membrane composed of simple squamous epithelium and capillary endothelium
   • C) A dense layer of smooth muscle tissue encircling each individual alveolar sac
   • D) A continuous barrier of stratified cuboidal cells lining the inner alveolar surface
5. 5.

   Which mechanism directly drives the exchange of oxygen and carbon dioxide across the respiratory membrane between alveoli and pulmonary capillaries?

   • A) Primary active transport utilizing ATP-dependent carrier proteins in type I alveolar cells
   • B) Bulk fluid movement driven by differences in hydrostatic and osmotic pressures
   • C) Facilitated transport mediated by voltage-gated ion channels along the capillary endothelium
   • D) Passive diffusion down the partial pressure gradients of each individual gas