Physio Practice Test 2

Diffusion defect hypoxia refers to a type of hypoxia where there is impaired diffusion of oxygen from the alveoli into the bloodstream. This can occur due to conditions such as pulmonary fibrosis or pneumonia, where the alveolar membrane becomes thickened and impairs gas exchange. Therefore, the correct answer is C. hypoxic, as diffusion defect hypoxia is a specific type of hypoxia.

Transection of the brainstem below the medulla refers to a complete severing of the neural connections in the brainstem below the medulla. The medulla is responsible for controlling basic automatic functions such as respiration. Therefore, if the brainstem is transected below the medulla, the connection between the brain and the respiratory muscles is disrupted, leading to the cessation of respiration. This means that breathing will stop completely.

The work of breathing refers to the effort required to inhale and exhale air. Surface tension elasticity refers to the property of the alveoli in the lungs to resist collapsing during exhalation. This resistance is due to the presence of a thin layer of fluid lining the alveoli, which creates surface tension. This surface tension elasticity plays a significant role in reducing the work of breathing by preventing the alveoli from collapsing completely and making it easier for air to be exhaled. Therefore, surface tension elasticity is mostly responsible for the work of breathing.

The Pre-Botzinger nucleus is responsible for generating the automatic rhythmic respiration in the body. It is a group of neurons located in the medulla oblongata that acts as a pacemaker for breathing. These neurons generate the basic rhythm for breathing and coordinate the activity of the respiratory muscles. Therefore, option b) is the correct answer.

The VA/Q ratio at the base of the lungs is 0.6. This means that the ventilation-perfusion ratio at the base of the lungs is 0.6, indicating that there is a higher ratio of ventilation (VA) compared to perfusion (Q). This could be due to factors such as gravity causing increased ventilation at the base of the lungs or decreased blood flow to the base of the lungs.

Specific compliance refers to the compliance of a specific region or part of the lungs, rather than the overall lung compliance. It is calculated by dividing the change in volume by the change in pressure in that specific region. In this case, the correct answer is a. C/FRC, which means that specific compliance is measured by dividing the change in volume by the change in pressure at functional residual capacity (FRC), which is the volume of air remaining in the lungs after a normal exhalation.

The normal ratio of physiological to anatomical dead space is 1:1. Physiological dead space refers to the portion of the respiratory system that does not participate in gas exchange, such as the trachea and bronchi. Anatomical dead space refers to the volume of air in the conducting airways. The ratio of 1:1 indicates that the physiological dead space is equal to the anatomical dead space, meaning that there is an equal amount of non-functional airways as there is air that participates in gas exchange.

Lung diffusion capacity is measured by carbon monoxide because it is a gas that has a high affinity for hemoglobin in the blood. When inhaled, carbon monoxide binds to hemoglobin and is transported to the lungs, where it can be measured to determine how efficiently oxygen is being transferred from the lungs to the bloodstream. This test helps to evaluate lung function and diagnose conditions such as emphysema and pulmonary fibrosis.

The ventilation/perfusion ratio refers to the ratio of the amount of air reaching the alveoli (ventilation) to the amount of blood flow reaching the alveoli (perfusion). In the upright position, the gravitational force causes more blood to flow to the base of the lungs compared to the top. As a result, the ventilation/perfusion ratio is lower at the base because there is less ventilation relative to perfusion. This means that the base of the lungs is less efficient in terms of gas exchange compared to the top.

The correct answer is d) bicarbonate in plasma. Carbon dioxide is mainly carried in the blood as bicarbonate ions. When carbon dioxide enters the red blood cells, it combines with water to form carbonic acid, which then dissociates into bicarbonate ions and hydrogen ions. The bicarbonate ions are transported out of the red blood cells and into the plasma, where they are carried to the lungs for elimination. This bicarbonate transport mechanism helps to regulate the pH of the blood and maintain the acid-base balance in the body.