The time required for the atrial impulse to travel through the atrioventricular node is defined as which of the following?
a. P–R segment c. QRS interval
b. P–R interval d. ST segment
ANS: B
The P–R interval ranges from 0.12 to 0.2 second and is the time it takes for the impulse initiated in the atria to travel through the atrioventricular node. The P–R segment occurs between the end of the P wave and the beginning of the QRS interval, corresponds to the 0.1-second delay that occurs within the atrioventricular node. The P–R segment is included in the P–R interval. The QRS interval represents ventricular depolarization, and the ST segment represents ventricular depolarization.
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When pressure increases, flow:
A) stays the same. B) varies. C) increases. D) decreases.
Which of the following statements accurately describe pulmonary vascular capacitance? I. During lung inflation, vascular capacitance increases within the alveolar vessels. II. During hypervolemic states, lung inflation causes a discharge of alveolar blood volume into the left atrium. III. During dehydration, lung inflation will cause a transient decrease in the pulmonary venous overflow as blood
pools in the extra-alveolar vessels. IV. Vascular capacitance decreases in the extra-alveolar vessels during lung inflation. A. III only B. I, II, IV only C. I, III, IV only D. II, III, IV only