AN INVITATION TO READERS
T
he editors welcome readers’ contributions in the form of letters about any aspect of physiology education. Please write to the Editor,Advances in Physiology Education, American Physiological Society, 9650 Rockville Pike, Bethesda, MD 20814-3991.LETTERS TO THE EDITOR
Misconceptions in Physiology
To the Editor:
I was delighted to read the article on students’ misconceptions by Michael et al. (1). It brings to fore an issue that has engrossed me for nearly a decade and one-half. My own con-cern for students’ misconceptions finds a mention too in another article in the same issue of Advances in Physiology Education(5), wherein I have pleaded that encouraging stu-dents to write multiple-choice ques-tions may be a systematic way of bringing to light some of their mis-conceptions. I am, however, more concerned about teachers’ miscon-ceptions that tend to propagate widely.
For years, I had believed that miscon-ceptions were largely prevalent among teachers in India and other third-world countries that do not have easy access to good, authentic textbooks. For the same reason, I thought that the issue of misconcep-tions would not interest an interna-tional audience. However, working at the University of Texas Austin as a Fellow of the International Union of Physiological Sciences, I was con-vinced about the universality of mis-conceptions. At the Human Anatomy
and Physiology Conference in 1996 held in Portland, Oregon, I gave a spot quiz (a questionnaire with 13 questions) to the participants. Thirty-two teachers responded. Some of those questions are reproduced be-low. The figures in brackets indicate the percentage of respondents who checked each option. Without de-bating the most appropriate an-swers, whatcanbe said is that there is little agreement among teachers on certain basic questions in physi-ology that can be enough reason for creating confusion among students.
A patient is said to be anemic if his/ her . . .
a. hemoglobin concentration is sub-normal (15.6%)
b. red cell count is subnormal (15.6%)
c. either (43.8%)
d. both (25%)
During exercise . . .
a. the end-diastolic volume of the heart increases (43.8%)
b. the end-systolic volume of the heart decreases (9.4%)
c. both (31.3%)
d. neither (12.5%)
During exercise, hyperventilation occurs due to . . .
a. increased arterial PCO2(59.4%)
b. decreased arterial PO2(6.3%)
c. both (12.5%)
d. neither (21.9)
The apical alveoli of the lungs have a greater PO2because . . .
a. apical alveoli are larger (6.3%)
b. apical alveoli are better ventilated (53.1%)
c. both (6.3%)
d. neither (25%)
During sphygmomanometry, the ma-nometer should be kept at the level of . . .
a. the eye (12.5%)
b. the heart (65.6%)
c. both (3.1%)
d. neither (18.8%)
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It is noteworthy that only 12.5% of the teachers felt that during sphygmoma-nometry, the manometer needs only to be kept at the eye level. The popu-lar misconception that the manometer should be at the heart level during sphygmomanometry probably stems from the principles of direct blood pressure measurement. For over a de-cade, I have been frustrated in my ef-forts to eradicate this misconception. A letter published by myself in a pop-ular Indian medical journal for practi-tioners (4) not unexpectedly had little impact, largely because the books are not on my side. Most of them, includ-ing cardiology books (3), are silent on the issue. An article in theBritish Med-ical Journal(2), although mentioning that the manometer was to be kept at eye level, does not stress the redun-dancy of keeping the manometer at the heart level. However, one illustra-tion in it does show the manometer-placed well above the heart level.
Hutchison’s Clinical Method (6), a book that is widely read by medical students, maintained through succes-sive editions that “the manometer is placed so as to be at the same level as
the observer’s eye.” However, in a complete turnabout in its 20th edition (7), the book modified the statement, saying “The manometer is placed so as to be at the same level as the cuff on the patients arm and the observer’s eye.” It meant by implication that the manometer had to be placed at the level of the heart (since the cuff must be at the heart level), and the observ-er’s eyes had to be brought to that level. It goes to show how misconcep-tions, if sufficiently widespread, can make inroads into some of the best books! It has left me feeling the need for a forum at which such questions can be authoritatively addressed and misconceptions effectively weeded out. A column in the Advances in Physiology Education in which emi-nent teachers and research scholars are invited to answer readers’ queries in physiology might just be the right step in that direction.
SABYASACHI SIRCAR Department of Physiology
University College of Medical Sciences Delhi, India 110095
sircarss@bol.net.in
REFERENCES
1. Michael JA, Richardson D, Rovick A, Modell H, Bruce D, Horwitz B, Hudson M, Silverthorn D, Whitescarver S, and Williams S.Undergraduate students’ mis-conceptions about respiratory physiology.
Am J Physiol Adv Physiol Educ277: S127– S135, 1999.
2. O’Brien ET, and O’Malley K. ABC of blood pressure measurement.BMJ2: 775– 776, 1979.
3. O’Rourke RA, Shaver JA, Salerni R, Sil-verman ME, and Schlant RC.The his-tory, physical examination and cardiac aus-cultation: measurement of systemic blood pressure. In:Hurst’s Heart, Arteries and Veins, edited by Alexander RW, Schlant RC, and Fuster V. New York: McGraw-Hill, 1998, p. 254 –256.
4. Sircar SS.The level of the heart: its rele-vance in sphygmomanometry.J Ind Med Assoc92: 381, 1994.
5. Sircar SS and Tandon OP.Involving stu-dents in question writing: a unique feed-back with fringe benefits.Am J Physiol Adv Physiol Educ22: S84 –S91, 1999. 6. Swash M and Mason S.Hutchison’s
Clin-ical Method. East Sussex, UK: Bailliere Tin-dal, 1989: p. 225.
7. Swash M.Hutchison’s Clinical Method. London: Saunders, 1995, p. 169.
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