Medical Physiology Online

Peer reviewed, open access journal. ISSN 1985-4811.

Archive for January 2008

Ask a Question: a new type of contribution to MPO

leave a comment »

A LETTER FROM THE EDITOR

Dear readers:

I am pleased to inform you that we are inviting a new type of contribution to MPO. This new section is called “Ask a question”. Quite often, we raise questions that we may not have an answer for. It is probably just a matter of asking that question to the right people and the answer will come from somewhere or at least we may know if nobody can answer our question.

MPO will be happy to serve as a platform for fielding questions that are in the direction of the journal’s mission and scope.

To get this section started, we have a question from Pavithran (access here), a student advisor for MPO.

Should this question interest you, we invite you to answer it. We will consider publishing responses that answer the question convincingly. Please submit your response using the “Leave a Comment” option. Depending on the question, I plan to review readers’ responses myself or delegate them to a guest editor who would be interested in working on the question. 

Although at the moment there is no formal limit on the number of responses that will be published in response to a question, I indeed plan to close the discussion when a question has been convincingly answered. When this happens, readers will no longer see a “Leave a Comment” option at the end of such a contribution. Thus, I would encourage you to respond as early as you can (in a week or so).

Please also encourage your colleagues and students to funnel questions into this section of the journal and ignite the spirit of curiosity that is there in all of us to be harnessed. Please also feel free to e-mail this post to your colleagues.

I should finish quoting Albert Einstein: “The important thing is not to stop questioning”.

Yours sincerely,

E.S.Prakash,

Editor, Medical Physiology Online
E-mail: medicalphysiologyonline at gmail dot com

Please cite this letter as: Prakash E.S. Ask a question: a new type of contribution to MPO. Medical Physiology Online 30 Jan 2008, available from http://www.medicalphysiologyonline.org

Advertisements

Written by E.S.Prakash

January 30, 2008 at 11:29 AM

Point of View: What is the difference between tetanus and tetany?

with 9 comments

E.S.Prakash, School of Medicine, Faculty of Medical and Health Sciences,

Asian Institute of Medicine, Science & Technology, 08100 Bedong, Kedah Darul Aman, Malaysia.

E-mail: medicalphysiologyonline at gmail.com

Submitted 1 Jan 2008; accepted 16 Jan 2008; published 16 Jan 2008

Download Full Text

 

Here is a common dialog between a physiology teacher and an undergraduate student during a physiology examination: 

Teacher: What is the difference between tetanus and tetany?

Student: Tetanus is a disease caused by Clostridium tetani whereas tetany is a consequence of hypocalcemia.

Teacher: You are correct.

My comments: While there is nothing really wrong with the above dialog, it reads as though tetanus and tetany are two different things. My point is, in a mechanistic sense, there is little difference between tetanus and tetany but this is not commonly noted. Let me explain.

The clinical condition “tetanus”, caused by Clostridium tetani, is characterized by painful muscle spasms and rigidity; this is because the toxin tetanospasmin which C. tetani produces is a powerful inhibitor of the release of glycine, an inhibitory neurotransmitter, from Renshaw cells in the spinal cord. When this happens, unrestrained high frequency discharge of alpha motor neurons results in sustained skeletal muscle contractions that we call tetanus.

Experimentally, for example with a frog sciatic nerve-gastrocnemius muscle preparation, we “tetanize” the muscle by stimulating the sciatic nerve supplying the muscle (or the muscle itself) at high frequencies (called tetanizing frequencies); in other words, we are exciting α-motor neurons supplying the muscle at high frequencies. Strictly speaking, a muscle is said to be tetanized completely if there is no relaxation between successive contractions. To be tetanized, skeletal muscle needs to be stimulated at a frequency greater than or at least equal to the reciprocal of the contraction period in seconds.

Hypocalcemia is said to increase neuromuscular excitability by reducing the magnitude of depolarization necessary to initiate changes in the Na and K conductance that produce an action potential [1]. The carpopedal spasm that occurs in hypocalcemia is evidence of increased neuromuscular excitability and must be due to increased discharge of motor neurons supplying the corresponding muscles. Indeed, Mullin and colleagues [2] have demonstrated the occurrence of opisthotonus, pleurothotonus, and rigidity of abdominal musculature in experimental dogs in which hypocalcemia was induced by injecting calcium poor solutions into the cisterna magna. Thus, the neuromuscular consequences of tetanotoxin and hypocalcemia are similar.

Conflict of interest: the author is the editor of Medical Physiology Online.

Reference: [1] Ganong WF. Chapter 2. Excitable Tissue: Nerve; In: Review of Medical Physiology, 22nd edition, Mc Graw Hill Co, New York, 2005.

Please cite this article as: Prakash ES. What is the difference between tetanus and tetany? Medical Physiology Online, 16 Jan 2008; available from http://www.medicalphysiologyonline.org

Copyright © 2008 E.S.Prakash. This is an open access article distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by-nc-sa/3.0/

Guest editor for this manuscript: Dr. Madanmohan, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India. E-mail: drmadanmohan123 at gmail dot com

Conflict of interest: E.S.Prakash invited me to review this manuscript. He was my student from 2001 through 2006. We have worked and published several articles together.

Prepublication record: The prepublication record for this manuscript MPO-001-2008 containing the draft manuscript, readers and editor’s comments can be accessed from http://www.medicalphysiologyonline.org

 

Written by E.S.Prakash

January 16, 2008 at 12:20 PM

Restoring the joy in learning

leave a comment »

Eugene A. Stead*, Jr. and C. Frank Starmer

Duke-National University of Singapore Graduate Medical School, Singapore 169547

E-mail: frank.starmer at gms.edu.sg

* deceased.

Original source of this article: http://frank.itlab.us/stead/joy.html, accessed 16 Jan 2008

Reproduced in Medical Physiology Online 16 Jan 2008 with permission from Dr Starmer

Download Full Text

Each time our grandchildren visit, we have the opportunity to observe what is exciting and what is boring. Up to the age of 10 or 12, they visit with a curiosity and energy that fills us with a bit of their energy and excitement. The visits are fun and we enjoy the opportunity to expand the fire of their curiosity.

Then something happens – as they enter the teenage years, their curiosity and excitement dwindles. Each of us has observed this with multiple grandchildren. The question for us, two individuals excited by the opportunities to grow the next generation of folks that will contribute to our social and economic fabric, is what happens to extinguish their curiosity?

We think back to our own youth and remember that we were part of an education system – something that was formal, structured and focused on pushing us to remember our arithmetic tables, correct spelling, and historical facts. One of us was a good memorizer (Gene) while the other was a poor memorizer (Frank) – but both of us struggled to find the fun in education and came to the conclusion that there is no fun in education – simply because it is the process of filling our heads with concepts and facts we may never use again. Where is the relevance? Fortunately, we were rebel enough to discover that there was another world – that of learning, and we had fun learning. Learning for each of us was experimental, we tried this and that; we disassembled a motor and could not correctly reassemble it. But our parents were fond of us and became our facilitators, helping us with reassembling a motor or radio or developing photographs or cooking a loaf of bread.

There are very few families today where there is one stay-at-home parent so that fueling curiosity is left to our public and private schools. They struggle with maintaining curiosity but are limited by the requirement that their classes must touch the least talented student while maintaining the excitement of the most talented student.

We believe that the attenuated curiosity of our grandchildren is a reflection of the averaging of the educational process that occurs in the traditional classroom. We believe, though, that with a little imagination, the averaging process can be abandoned in favor of what we call internet-centric learning.

The internet simply reflects electronic connections between computer memories located around the world. Because this memory is electronic, it has a degree of reliability far beyond that of our biological memory. So we ask, why do we insist that our grandchildren memorize the same information we memorized (but rarely used)? The internet levels the knowledge playing field. The curious student from a depressed region has access to the same information that the brightest Duke professor has. The only missing link is the facilitator.

We believe it is time to revisit our educational paradigm and question the utility of mastering facts we’ll rarely use. We believe it is time to revisit the relationship between members of our educational programs. We prefer to dismiss the concept of education and replace it with learning. We prefer to dismiss the concept of faculty and students and replace it with a community of learners, senior (experienced) and junior (inexperienced) learners. We prefer to dismiss the concept of broad-based content mastery and replace it with mastery of essential core skills (reading, writing, arithmetic and searchology – the skilled use of google.com).

Educational reform starts in the home, where parents must equip their children with access to the world’s information stores. Education continues in the schools where we can compress the 12 years of primary and secondary education required to memorize basic information to perhaps 6-8 years of understanding basic concepts and supplementing our human memory with the memory of the internet. Education continues within our universities and professional schools, where we can produce workers that can make significant contributions to society with less faculty and less time than at any time in the past. Why? Because the repetitive actions needed to memorize and then understand will be replaced by the repetitive actions needed to simply master concepts within the context of our internet memory. Moreover, forgetting is less of a problem. Many educators fail to understand that there is a sort of symmetry in learning and maintaining that which we learned. If we rarely use a concept or rarely recall a fact, we forget it. You can view a sort of forgetting curve [1] where the less frequently we use something, the more likely we are to forget it.

Our internet, our internet memory, our search engine skills, for the first time can address both the learning process and the forgetting process. By focusing our learning within a problem based framework, we know we are learning only that necessary to solve the problem, i.e. just-in-time learning. Thus forgetting is less an issue simply because we have not invested considerable time in learning things we rarely use.

Conflict of interests: none

Reference:

[1] The forgetting curve. http://frank.itlab.us/forgetting/index.html#curve accessed 16 January 2008

Copyright © C Frank Starmer. This is an open access article distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by-nc-sa/3.0/

Editor’s note: I wanted to reproduce this article in Medical Physiology Online. I am grateful to Dr C Frank Starmer for granting us permission to do so. Dr Starmer is a member of the advisory board of Medical Physiology Online. Please visit Dr. Starmer’s internet laboratory at http://frank.itlab.us. The web site of the late Dr. Eugene Stead now maintained by Dr Starmer is http://easteadjr.org. I have no conflict of interests to disclose.

E.S.Prakash, Editor, Medical Physiology Online

Written by E.S.Prakash

January 16, 2008 at 10:30 AM

The Power of Pranayam

leave a comment »

Madanmohan, Department of Physiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry 605006, India. E-mail: drmadanmohan123 [at] gmail [dot] com

Received 14 January 2008; accepted 15 January 2008; published 16 January 2008

Download Full Text

Indian classical traditions including yoga emphasize the existence of pran, the infinite and omnipresent cosmic energy. This whole creation, Mother Nature is bountiful. So is pran. At the physical level, pran manifests as light and other forms of physical energy. In our body, pran is the vital force that energizes us. The science of pranayam (a yogic breathing technique) deals with the knowledge, control and enrichment of this vital force. The classical Upanishads, which were written over 5000 years ago, give us guidelines about pranayam. Prashn Upanishad (2:13) describes pran as the universal governing force that protects and enhances us like our mother. The Bhagavad Gita describes pran and pranayam in a number of verses. Patanjali’s Rajayog and many tantrik texts describe a number of graded practices including pranayams that help us understand and harness this infinite reservoir of energy. The popular complementary healing systems pranic healing and reiki are based on the concept of pranic energy. Indian yogis and ayurvedic physicians have used the power of pranayam for healing since time immemorial.

The mind and body are intricately interrelated. Besides wasting energy, irregular breathing is associated with a restless mind. In contrast, slow, deep and uniform pranayam breathing produces psychosomatic relaxation especially when it is associated with meditative awareness. During pranayam, one can follow the breath as it flows in and out. One can also visualize cosmic pran flowing into the body and mind with each inspiration enlightening the whole being. According to yogic texts, the practice of pranayam results in inner peace and joy, broadening of vision and development of positive emotions like unselfish love. Pranayam is described as a means to achieving divinity and perfection. According to Patanjali (Yoga Darshan, 2: 52–53) pranayam unfolds the inner light and improves the power of concentration.

We have previously reported [1] that savitri pranayam (slow, rhythmic and deep breathing with a ratio of 2:1:2:1 between inspiration, breath held in inspiration, expiration and breath held in expiration) produces a significant reduction in oxygen consumption and deep psychosomatic relaxation within 5 minutes. Telles and Desiraju [2] have demonstrated that a variant of pranayam breathing is associated with a 19% reduction in oxygen consumption. In a study on healthy children who underwent pranayam training for 3 months, Udupa et al [3] have inferred modulation of ventricular performance as indicated by systolic time intervals. In an 18-year old female with frequent premature ventricular complexes (PVC), Prakash et al [4] found that deep breathing at 6 breaths per minute abolished PVC; a significant reduction in the frequency of PVC during deep breathing at 6 breaths per minute has been reported in at least a subset of patients with unifocal PVC. The beneficial effect of deep breathing was suggested to be due to increased vagal modulation of sinoatrial and atrioventricular nodes. Ravindra et al [5] have shown that pranayam and relaxation training for 2 months reduced the frequency of palpitations in two patients with frequent PVC.

Given this evidence, I believe it is important to continue to investigate the physiologic effects of pranayam using scientifically valid methods and apply encouraging results to determine their effects on human health. The power of pranayam is there for all of us to harness. That is my opinion.

Conflict of interests: none

References:

[1] Madanmohan, Rai UC, Balavittal V, Thombre DP. Cardiorespiratory changes during savitri pranayam and shavasan. The Yoga Review 3: 25-34, 1983

[2] Telles S and Desiraju T. Oxygen consumption during pranayamic type of very slow-rate breathing. Indian Journal of Medical Research 1991; 94: 357-363, abstract available at http://www.ncbi.nlm.nih.gov/pubmed/1794892 accessed 15 Jan 2008

[3] Udupa K, Madanmohan, Bhavanani AB, Vijayalakshmi P, Krishnamurthy N. Effect of pranayam training on cardiac function in normal young volunteers. Indian Journal of Physiology and Pharmacology 43: 27-33, 2003; full text available at http://www.ijpp.com/vol47_1/vol47_no1_orgn_artcl_1.htm accessed 15 Jan 2008

[4] Prakash ES, Ravindra PN, Madanmohan, Anilkumar R and Balachander J. Effect of deep breathing at six breaths per minute on the frequency of premature ventricular complexes. International Journal of Cardiology 111: 450-452, 2006; abstract available at http://www.ncbi.nlm.nih.gov/pubmed/17004338 accessed 15 Jan 2008

[5] Ravindra PN, Madanmohan and Pavithran P. Effect of pranayam (yogic breathing) and shavasan (relaxation training) on the frequency of benign ventricular ectopics in two patients with palpitations. International Journal of Cardiology 108: 124-125, 2006; link to full text at  http://www.ncbi.nlm.nih.gov/pubmed/16516708

Please cite this article as: Madanmohan. The power of pranayam. Medical Physiology Online, 16 Jan 2008, available from http://www.medicalphysiologyonline.org

Editor’s note – conflict of interest: I commissioned, reviewed and edited this manuscript. I was Dr. Madanmohan’s student from 2001 through 2006. We have worked and published several articles together.

E.S.Prakash, Editor, Medical Physiology Online.

Written by E.S.Prakash

January 16, 2008 at 10:00 AM

Posted in Uncategorized