09 Quiz info

09 Quiz info - Physiology 202 CCO Summer 2011 Lesson 9 Quiz...

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Physiology 202 CCO, Summer, 2011 Lesson 9 Quiz The mean (average) on this quiz was 88.15%. Seven students scored 90% or above and one student scored 100%!!! The distribution of scores is shown in the graph to the right. Explanations for Selected Questions 1. For a normal adult, systemic arterial pressure, measured with a sphygmomanometer from the left brachial artery, was 125/65. Pressure in the pulmonary arteries was 24/10. Choose the best answer for the following questions based on the information provided above. Choices are in parentheses. Consider a normal cardiac cycle. The most logical way to approach this sort of question is to identify the “givens”. It was given that the systemic arterial pressure was “125/65”. This means that systemic arterial systolic pressure is 125 mmHg and systemic arterial diastolic pressure is 65 mmHg during each cardiac cycle. It was also given that the pulmonary arterial pressure was “24/10”. This means that pulmonary arterial systolic pressure is 24 mmHg and pulmonary diastolic pressure is 10 mmHg during each cardiac cycle. These are illustrated in the following figure. Note that the following illustrates 4 cardiac cycles for each component. 1
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We can also put those given pressures on a Wiggers diagram for the left heart… and for the the right heart. 2
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You can also put the givens in the following representation. The givens are in boxes. So, now let’s look at the questions. Contraction of the left ventricle increases left ventricular pressure to a maximum of about [A] mmHg. Left ventricular pressure then drops to nearly [B] mmHg and rises only a slight amount until the left ventricle contracts again. (125, 100, 65, 24, 10, 3) This question is essentially the same as Question 2 in Lesson 8 Quiz. During each cardiac cycle, left ventricular pressure increases up to a peak that is essentially the same as systolic arterial pressure and then drops to close to 0 mmHg. So, the best answers from the choices given are: Contraction of the left ventricle increases left ventricular pressure to a maximum of about 125 mmHg. Left ventricular pressure then drops to nearly 3 mmHg and rises only a slight amount until the left ventricle contracts again. If you are confused about this, please refer back to the explanations for Lesson 8 Quiz. You were given that systemic arterial pressure was 125/65. Because the pressure in the aorta is essentially the same as pressure in other systemic arteries, the answers to the next question are: Aortic pressure rises to a maximum of about 125 mmHg and then decreases to a minimum of about 65 (125, 100, 65, 24, 10, 3) The aortic semilunar valve opens when the rising pressure in the left ventricle just exceeds the pressure in the aorta. For this individual, the pressure in the aorta and the pressure in the left ventricle when the aortic semilunar valve opens is about [E] mmHg. (125, 100, 65, 24, 10, 3) The above question forces you to understand some of the origins of arterial diastolic pressure and its relationship to ventricular pressure. When we say that systemic arterial pressure is “125/65” (this example), we are saying that the pressure 3
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This note was uploaded on 06/14/2011 for the course PHYI 202 taught by Professor Shea during the Summer '09 term at UNC.

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09 Quiz info - Physiology 202 CCO Summer 2011 Lesson 9 Quiz...

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