Otago HSFY chat - archive

[Wongtong]

Is it likely for examples in the lectures to be tested on (I'm referring to the past few CELS lectures) or is it best to just stick to learning the objectives in the lecture handout?

 

[Caesar]

Hey guys, of 0.45% NaCl and 5% glucose, which is safe for intravenous injection?

I guessed the 0.45% NaCl seeing as glucose would end up being taken up by cells and/or metabolised.

 

[informedconsent]

Hey guys, of 0.45% NaCl and 5% glucose, which is safe for intravenous injection?

I guessed the 0.45% NaCl seeing as glucose would end up being taken up by cells and/or metabolised.

The "Normal" IV value for NaCl is 0.90% and Glucose at 5% is also a standard concentration. As I haven't actually seen the question I can't tell you if those values mean anything in relation to the test, but those are the values nonetheless.

 

[juna]

Hi guys! I hope everyone did well for HUBS! Personally I hated that test...... Why on earth did I spend that much time learning ABSOLUTELY everything in the lecture slides!!!!!!!!!!!!
A question- I have been doing group worksheets on blackboard and I was wondering how the actual exam compared with those worksheets? I know that the content will be different, but as far as the style of questions and level of difficulty- detail goes, would you say its quite similar? Thanks

 

[frootloop]

A question- I have been doing group worksheets on blackboard and I was wondering how the actual exam compared with those worksheets? I know that the content will be different, but as far as the style of questions and level of difficulty- detail goes, would you say its quite similar? Thanks

I assume you mean CELS? If so, then I found the worksheets required more detail than the terms test did. That said, our terms test was done ludicrously well by students on average (so it was pretty easy), and so it may be made a little harder this year.

 

[Cathay]

A question- I have been doing group worksheets on blackboard and I was wondering how the actual exam compared with those worksheets? I know that the content will be different, but as far as the style of questions and level of difficulty- detail goes, would you say its quite similar? Thanks

And if you were asking about the final exams, I shall refer you to the library exams website where you can get the past exam papers and have a lookie yourself.

 

[juna]

And if you were asking about the final exams, I shall refer you to the library exams website where you can get the past exam papers and have a lookie yourself.

Oops, sorry, I did not make that clear at all. I meant for cels worksheets and the upcoming cels mid semester test

 

[Cathay]

Hey guys, of 0.45% NaCl and 5% glucose, which is safe for intravenous injection?

I guessed the 0.45% NaCl seeing as glucose would end up being taken up by cells and/or metabolised.

0.45% NaCl has an osmolarity of 154mmol/L -> hypo-osmotic -> hypotonic -> cells would swell up and pop if you injected it. So unfortunately that's a no-go.

Just to clarify, 5% glucose IS hypotonic, because you're quite right, glucose would end up being taken up (and metabolized) by cells, but, and this is a fairly significant but, glucose isn't nearly as permeable as urea (which was another option I believe?), so glucose is taken up by cells gradually via transporters, so the solution's water concentration (which is the important part - it dictates whether water goes into or out of the cell via osmosis) increases gradually. Because of this gradual increase of water concentration, rather than rapid increase (urea solution) or just very high to start with (0.45% NaCl), the solution mixes with blood as this gradual increase of water concentration is happening, so instead of flooding cells around the injection site with water (which both the 0.45% NaCl and the urea would end up doing), the glucose solution eventually increases the water concentration (i.e. lowers the osmolarity) of blood, but this is normally corrected by the kidneys which get rid of the excess water. (Many thanks to @skyglow1 and @greenglacier for explaining this to me!)

So as you can see, the deal with glucose is complicated, so I'm more inclined to think that this question was seeing whether you guys knew that 1) 0.45% NaCl is not iso-osmotic, you can calculate it, 2) you don't want to inject KCl (refer to homeostasis lecture where normal potassium level is mentioned, and what happens if you raise it is mentioned too), and 3) an iso-osmotic urea solution is not isotonic - that was the example in the lecture about why iso-osmotic =/= isotonic. In other words, it was about eliminating the ones you know are wrong, and sometimes in MCQs that's what you have to do - see which ones are definitely wrong, rather than which one is definitely right.

 

[Caesar]

0.45% NaCl has an osmolarity of 154mmol/L -> hypo-osmotic -> hypotonic -> cells would swell up and pop if you injected it. So unfortunately that's a no-go.

Just to clarify, 5% glucose IS hypotonic, because you're quite right, glucose would end up being taken up (and metabolized) by cells, but, and this is a fairly significant but, glucose isn't nearly as permeable as urea (which was another option I believe?), so glucose is taken up by cells gradually via transporters, so the solution's water concentration (which is the important part - it dictates whether water goes into or out of the cell via osmosis) increases gradually. Because of this gradual increase of water concentration, rather than rapid increase (urea solution) or just very high to start with (0.45% NaCl), the solution mixes with blood as this gradual increase of water concentration is happening, so instead of flooding cells around the injection site with water (which both the 0.45% NaCl and the urea would end up doing), the glucose solution eventually increases the water concentration (i.e. lowers the osmolarity) of blood, but this is normally corrected by the kidneys which get rid of the excess water. (Many thanks to @skyglow1 and @greenglacier for explaining this to me!)

So as you can see, the deal with glucose is complicated, so I'm more inclined to think that this question was seeing whether you guys knew that 1) 0.45% NaCl is not iso-osmotic, you can calculate it, 2) you don't want to inject KCl (refer to homeostasis lecture where normal potassium level is mentioned, and what happens if you raise it is mentioned too), and 3) an iso-osmotic urea solution is not isotonic - that was the example in the lecture about why iso-osmotic =/= isotonic. In other words, it was about eliminating the ones you know are wrong, and sometimes in MCQs that's what you have to do - see which ones are definitely wrong, rather than which one is definitely right.

Oh balls. So it wouldn't "split out" and have an osmolarity of 0.9% for a 0.45% solution of NaCl, as NaCl produces 2mol osmotically active particles per mol in solution?

 

[Calem]

Oh balls. So it wouldn't "split out" and have an osmolarity of 0.9% for a 0.45% solution of NaCl, as NaCl produces 2mol osmotically active particles per mol in solution?

iso-osmolar = roughly 300 mOsmol/L
=150mmol/L NaCl
=15mmol/100mL
=877.5mg/100mL
=0.9g/100mL
=0.9%

 

[Ruth]

I assume you mean CELS? If so, then I found the worksheets required more detail than the terms test did. That said, our terms test was done ludicrously well by students on average (so it was pretty easy), and so it may be made a little harder this year.

[offtopic]Dammit, why couldn't you guys have done badly D:[/offtopic]

Is the cels test just the lectures or do we have to know the lab stuff too, like meiosis and mitosis? (I feel like I should know this but I can't find the info about the test anywhere...)

 

[frootloop]

[offtopic]Dammit, why couldn't you guys have done badly D:[/offtopic]

Is the cels test just the lectures or do we have to know the lab stuff too, like meiosis and mitosis? (I feel like I should know this but I can't find the info about the test anywhere...)

Trust me, a hard test wouldn't be a bad thing. Lets you separate yourself from the pack (assuming you've done the work ). Last year lab stuff wasn't examinable, although you'd best double-check that with your course book/blackboard/teaching fellows.

 

[Cathay]

Oh balls. So it wouldn't "split out" and have an osmolarity of 0.9% for a 0.45% solution of NaCl, as NaCl produces 2mol osmotically active particles per mol in solution?

It does split up, but as calem pointed out, "0.9% osmolarity" doesn't really cut it.

 

[Sam]

Miles for president

 

[Proshot]

Hey guys, just going through surface tension in the textbook, there wasn't any formulaes for anything to do with surface tension on the lecture notes and im sure the lecturer didn't really say anything.... do we need to know the formulaes for surface tension? plus the textbook questions are rediculous..

 

[Wongtong]

Miles for president

I want a tshirt with his face on it.

 

[Profiterole]

I want a tshirt with his face on it.

lol hell yea, he presence makes physics sooo much better

 

[Bluerock]

<3 Miles

 

[Nimbus2000]

people who DON'T love miles, should be lynched. they are definitely JEALOUS.

... the thermodynamics lecturer/physics head is pretty awesome too

 

[Cathay]

If this is the physics technician we're talking about, his name is Myles... an easy mistake to make