NBME 27 Flashcards
what is the bicarbonate carbonic acid buffer?
In healthy subjects, blood pH concentration is maintained at or near a physiologic value of 7.4 by several acid buffer systems, the most important of which is the bicarbonate-carbonic acid buffer.
It is coupled to the respiratory system through the exchange of carbon dioxide between the blood and the alveolo.
Changes in the ventilation affect the relationship of the buffer constituents and are responsible for appropiate compensation to acid base disturbances
moving the cut point higher for a test does what?
decreases sensitivity and increases specificity by increasing the number of false negatives and decreasing the number of false positive.
In this case, point A represents 100% sensitivity, the cut off point at which all people who have the disease test positive.
what does a arterivenous fistula result in?
AV fistulas result in a large flux of blood from the high pressure arterial system into the low resistance venous system.
In a normal heart, the increase preload results in greater cardiac output. High output heart failure may develop over time.
what is Pierre Robin syndrome?
abnormalities in the development of the first pharyngeal arch result in hypoplasia of the mandible and micrognathia leading to posterior displacement of the tongue.
The downward displacement of the tongue can lead to airway obstruction, hypoxia, feeding difficulty, and respiratory distress.
what happens to the nephron with aging?
the concentrating ability of the nephron in response to ADH decreases with time, which is reflected as a lower urine osmolality in older men as compared to younger men in the setting of water deprivation.
