The portion of hemoglobin that contains iron and binds oxygen is called
Heme
Collagen
Myosin
Globin
The Correct Answer is A
A. Heme: Heme is the iron-containing component of hemoglobin responsible for binding oxygen molecules. Each hemoglobin molecule contains four heme groups, and the iron ion at the center of each heme binds one oxygen molecule, allowing hemoglobin to transport oxygen efficiently from the lungs to peripheral tissues.
B. Collagen: Collagen is a structural protein found in connective tissues, skin, and bones. It does not participate in oxygen transport or bind oxygen and is unrelated to hemoglobin function.
C. Myosin: Myosin is a motor protein in muscle tissue responsible for contraction and movement. It has no role in oxygen transport or hemoglobin structure.
D. Globin: Globin refers to the protein chains (alpha and beta) of hemoglobin that provide structural support and influence hemoglobin’s shape and function. While essential for hemoglobin stability, globin does not directly bind oxygen; that role is performed by the heme groups.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Correct answer: True
Ventilation, the movement of air into (inhalation) and out of (exhalation) the lungs, depends on pressure gradients between the atmosphere and the alveoli. During inspiration, the diaphragm and intercostal muscles contract, expanding the thoracic cavity and lowering intrapulmonary pressure below atmospheric pressure, allowing air to flow into the lungs. During expiration, these muscles relax, thoracic volume decreases, intrapulmonary pressure rises above atmospheric pressure, and air flows out. Without a pressure gradient, airflow cannot occur because gases move passively from regions of higher pressure to regions of lower pressure. This principle is fundamental to understanding normal respiratory mechanics and breathing physiology.
Correct Answer is A
Explanation
A. Diameter of the bronchioles: Airway resistance is most directly influenced by the radius of the airways, particularly the bronchioles. According to Poiseuille’s law, small changes in airway diameter result in exponential changes in resistance, making bronchiole constriction or dilation a primary determinant of airflow in the respiratory system.
B. Volume of alveolar fluid: While excessive alveolar fluid, as seen in pulmonary edema, can interfere with gas exchange, it has minimal direct impact on airway resistance. Resistance is determined by the path through which air flows, rather than the fluid volume within the alveoli themselves.
C. Thoracic wall elasticity: Thoracic wall elasticity affects lung compliance and the ease of lung expansion but does not directly regulate the resistance within the airways. Stiffness of the thoracic cage influences the work of breathing but is not the primary factor controlling airflow resistance.
D. Pulmonary surfactant levels: Surfactant reduces alveolar surface tension, preventing collapse and facilitating ventilation, but it has only an indirect effect on airway resistance. The main influence on resistance remains the bronchiole diameter rather than surfactant concentration.
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