Reminder: Lecture: General Physiology @ Fri 12 Aug 10am - 11am (UG Calendar: Physiology@KSHEMA)

more details » Lecture: General Physiology Mr. Shrikanth Patil General Physiology When Fri 12 Aug 10am – 11am India Standard Time Where Lecture Hall 1, K.S.Hegde Medical Academy (map) Calendar UG Calendar: Physiology@KSHEMA Who • physiol.kshema@gmail.com- organiser • physioloffice.kshema@gmail.com- creator

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Reminder: Lecture: Ethics @ Thu 11 Aug 2pm - 4pm (UG Calendar: Physiology@KSHEMA)

more details » Lecture: Ethics When Thu 11 Aug 2pm – 4pm India Standard Time Where Lecture Hall 1, K.S.Hegde Medical Academy (map) Calendar UG Calendar: Physiology@KSHEMA Who • physiol.kshema@gmail.com- organiser • physioloffice.kshema@gmail.com- creator

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Reminder: Lecture: General Physiology @ Thu 11 Aug 9am - 10am (UG Calendar: Physiology@KSHEMA)

more details » Lecture: General Physiology Shrikanth Patil General Physiology When Thu 11 Aug 9am – 10am India Standard Time Where Lecture Hall 1, K.S.Hegde Medical Academy (map) Calendar UG Calendar: Physiology@KSHEMA Who • physiol.kshema@gmail.com- organiser • physioloffice.kshema@gmail.com- creator

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Why 3.8% sodium citrate?

Naren, a first year Med student, has a question - why use 3.8% sodium citrate solution as an anticoagulant - why not a higher (or lower) concentration. Here is an attempt at answering it.

Sodium citrate is used as a anticoagulant because of its ability cause chelate calcium ions which as you know are essential for the clotting of blood. Sodium citrate is technically, Sodium tricitrate (Na₃C₆H₅O₇2H₂0). The citrate ions are responsible for chelating calcium ions. Higher the concentration of the sodium citrate solution used, better the anti-coagulation effect. However, with increasing concentration, the osmolarity of the anti-coagulant will increase and the blood cells collected in it will be subjected the effects of this osmolarity. Ideally, the concentration of the anti-coagulant should be equivalent to an osmalarity of about 300 mOsm, which would be iso-osomolar to that of plasma and therefore would have minimum osmolar effects on RBCs. At higher concentrations, the hyperosmolar anticoagulant solution would cause shrinkage of RBCs due to exosmosis and therefore would affect measurements such as packed cell volume and related blood indices.

Two forms of sodium citrate preparations are commonly used for anticoagulantion - 3.8% and 3.2% solutions. Let us see what is the osmolarity of these sodium citrate solutions.

3.8% solution = 3.8g/100L = 38g/L
Molecular weight of sodium citrate = 294g
38g/L = (38/294)Mol/L = 0.129 Mol/L = 129mMol/L
Now each molecule of sodium citrate gives three Na⁺ ions and one citrate ion in solution = total 3 osmotically active particles
129 mMol/L of sodium citrate would therefore have a osmalarity of 129 x 4 = 516 mOsm/L
3.8% sodium citrate provides good anticoagulation but is a little hypersomolar compared to plasma and therefore may have efects on RBC size.

3.2% sodium citrate solution has a osmolarity of 436 mOsm/L (calculation similar to that shown above).
This provides sufficient anticoagulation (although weaker than the 3.8% solution) and its osmolarity is closer to that of plasma (300mOsm/L) and would have less effects on RBC volume.

So the concentration of sodium citrate used is a balance between having enough to provide effective anticoagulation but not too much to prevent hyperosmotic RBC size changes.

The Anatomy Lesson of Nicolaes Tulp

I recently received via E-mail a funny story about "a anatomy lecture by Nicolaes Tulp". The story is something about an attempt by a beer-bamboozled Tulp claiming to tell the future by looking at forearm muscles or something to that effect. I thought some of you may want to know the real story behind "The Anatomy Lesson of Nicolaes Tulp"

(Image source: http://en.wikipedia.org/wiki/File:The_Anatomy_Lesson.jpg)

The Anatomy Lesson of Nicolaes Tulp is the title of a painting by the legendary Dutch painter Rembrandt van Rijn. Dr. Nicolaes Tulp was a popular surgeon in the early 1600s in the city of Amsterdam as well as a seasoned politician who in fact served as the Magistrate of this European city. Dr. Tulp was appointed as the Praelector Anatomiae of the Amsterdam Gulid of Surgeons which was something like being named the head of anatomy faculty by the Surgeons association. As the Praelector, he conducted anatomy dissection demonstrations and lectures for the guild members (something like present day Continuing Medical Education – CME programs or Workshops!). Such dissections were performed on male criminals who were hung to death. In 1632, Rembrandt, who was just 26 at the time, was commissioned to paint a group portrait of the Praelector Dr. Tulp and the guild members. This painting is acclaimed as one of his finest works and is an example of the use of a technique called chiaroscuro – the dramatic use of light and shadows.

A Self Portrait - Rembrandt van Rijn (1606 - 1669)

(Image source: http://en.wikipedia.org/wiki/File:Rembrandt_van_rijn-self_portrait.jpg)

Interestingly, this painting is actually one in a series of “Lesson series” of paintings. The others include The Osteology Lesson of Dr Sebastiaen Egbertsz by Thomas de Keyzer (1619) and The Anatomy Lesson of Dr Jan Deijman by Rembrandt van Rijn, 1656.

The Osteology Lesson of Dr Sebastiaen Egbertsz by Thomas de Keyzer (1619)
(Image Source: http://z.about.com/d/arthistory/1/0/u/W/dp_ngl_0707_02.jpg)

The Anatomy Lesson of Dr Jan Deijman by Rembrandt van Rijn, 1656.

(Imagesource: http://www.pandorawordbox.com/image.php?image=011634283)

To read more about these paintings, you could follow the following links

http://www.usyd.edu.au/hps/staff/hans/medart.htm

http://en.wikipedia.org/wiki/Nicolaes_Tulp

What do these results mean?

Take a look at my previous two posts on the examination results (scroll down). I think it is clear that the Internal assessment and viva marks have been critical for many of the students to pass in Physiology and Biochemistry. IA and viva marks were least in Anatomy and surprisingly performance in the University examination was best in Anatomy. In fact only two candidtaes depended on IA / viva for attaining the pass grade in Anatomy - the rest of you did well enough to pass in theory ON YOUR OWN!
The picture is quite different for Physiology and Biochemistry - 15 candidates passed thanks to IA / viva in Physiology while 17 needed a similar boost in Biochemistry.
So what does this suggest? A more frugal IA in Anantomy motivates students to work harder in that subject while the more liberal marking in Physiology means you take it less seriously?!
This is the way I look at it -

• Most of you are definitely capable of doing well enough in the theory examination PROVIDED you decide to work at it - the Anatomy results prove this
• Higher IA marks lulls you into a false security and is a cause for reduced motivation - the Physiology results suggests this
• Scoring well in Internal assessment tests is critical for a substantial number of students - it decides whether they pass or not
  

Well, do me a favour. If you think that this line of reasoning is right, then share your experience truthfully with your Juniors. Warn them about the complacency that high IA marks breed, stress the advantages of consistent performances in the Internal Assessment tests and most importantly, tell them that its possible to pass / do well in the University exams IF THEY APPLY THEIR MIND TO IT.

And the interesting point...

Now, here is a bit of revealing statistics
What if the performance in the theory paper alone was considered for determining the eligibilty of a candidate for promotion? In other words if Internal assessment was not considered...

No. of students who have scored 50% and above in the theory examination (papers alone):

Anatomy: 81/97 (83.50%)
Physiology: 71/97 (73.20)
Biochemistry: 60/97 (61.86%)
All three subjects: 54/97 (55.70%)