Respiratory Flashcards
What is vital capacity?
The exhaled volume after a maximal inspiration
What is tidal volume?
The amount of air entering the lung while breathing
What is residual volume?
The gas remaining in the lung after a maximal expiration
What is the functional residual capacity?
The volume of gas in the lung after a normal expiration
What is the alveolar ventilation?
The volume remaining in the anatomic dead space. It represents the amount of fresh inspired air available for gas exchange.
*Anatomic dead space is the volume of the conducting airways (where no gas exchange occurs)
What is total ventilation?
The total volume leaving the lung each minute.
Can be measured = (tidal volume x respiratory frequency )
What is called recruitment?
It’s the opening of vessels and conduction of blood through these vessels to lower overall vascular resistance. This happens when there is a rise in the pulmonary arterial or venous pressure.
What is called distension?
Is the increase in caliber of the capillaries when there is an increase in vascular pressure. Often occurs together with recruitment.
What effect do drugs like serotonin, histamine and norepinephrine (drugs that cause muscle contraction) have on the pulmonary vascular resistance?
They increase pulmonary vascular resistance. They are potent vasoconstrictors, specially when lung volume is low. This is due to the role of smooth muscle in determining extra-alveolar vessels caliber.
What is Zone 1 and when does it occur?
The region at the top of the lung when pressure falls below alveolar pressure impeding blood flow, therefore it becomes in alveolar dead space (it is ventilated but unperfused lung).
This only occurs when pressures are significantly reduced (after severe hemorrhage) or if alveolar pressures are raised (during positive pressure ventilation).
Rhodococcus equi is a ….
Gram-positive facultative intracellular bacterium. It is one of the most common causes of pneumonia in foals between 3 weeks and 5 months of age.
What is the pathogenesis of R. equi?
The ability of R. equi to persist in, and eventually destroy, alveolar macrophages seems to be the basis of its pathogenicity and inhalation the major route of pulmonary infection in foals.
Incubation period in experimental intrabronchial challenge (9 days to 2 - 4 weeks when a lower inoculum is administered). Incubation period under field conditions is unknown and varies depending several factors (number of virulent bacteria, age, host defense mechanisms). Lung consolidation can be detected as early as 3 days following heavy intrabronchial challenge.
What virulence factor is requiered for R. equi to grow within the macrophages?
Vap A, which encodes an immunodominant, temperature-inducible, and surface-expressed lipoprotein (it is the only vap gene with a demonstrated role in virulence).
VapA is required for intracellular growth in macrophages, once in the macrophage, it prevents maturation of the phagosome to the stage of fusion of R. equi –containing vacuoles with lysosomes.
