Otago HSFY chat - archive

[Steve]

What happened in chem?

 

[Sam]

What happened in chem?

I haven't a clue. The lecturer was.. so dull and covered really strange stuff. Really out of the blue.

 

[Bluerock]

I haven't a clue. The lecturer was.. so dull and covered really strange stuff. Really out of the blue.

Agreed. Had a hard time staying awake for that one.
Has anyone else found some revision materials for the terms test? Practice exams, etc? I've done the aptitute one already, and have thrashed peerwise. Apparently the PE students get copies of practice tests.

 

[frootloop]

Apparently the PE students get copies of practice tests.

I don't think so (there were like 4 on my floor at UniCol last year, and I never heard of any 'practice tests' being given to them, although they did get extra tutorial-type stuff, I think). I think if the PE students got practice tests, they'd be circulated through the HSFY cohort pretty quickly

 

[Bluerock]

Have a copy of it right here It's got misspellings all through it, looks like some sort of dodgy tutor group as you said.

[OFFTOPIC]Also, location the cook? LOL, brilliant![/OFFTOPIC]

 

[Caesar]

[MENTION=11852]Shaunasaur[/MENTION] HAVE I MENTIONED YOU'RE THE COOLEST GUY EVER

canihavethetestnowkthanks

Also, menisci, bony congruence, what. My understanding of bony congruence is that it has to be... bony. The menisci in the knee serve to provide shock absorption, along with a greater surface area for articulation at the joint amirite guys? Does it allow anything else? (eg would we say it is the structure of the menisci which allows slight (...rotation or abd/adduction?) of the flexed joint?)

 

[Sam]

@Shaunasaur HAVE I MENTIONED YOU'RE THE COOLEST GUY EVER

canihavethetestnowkthanks

Also, menisci, bony congruence, what. My understanding of bony congruence is that it has to be... bony. The menisci in the knee serve to provide shock absorption, along with a greater surface area for articulation at the joint amirite guys? Does it allow anything else? (eg would we say it is the structure of the menisci which allows slight (...rotation or abd/adduction?) of the flexed joint?)

I thought they said that bony congruence was just a measure of how much bone is support by x object. Aka the menisci in the knee provides the knee itself with increased bony congruence.

 

[Cathay]

Also, menisci, bony congruence, what. My understanding of bony congruence is that it has to be... bony. The menisci in the knee serve to provide shock absorption, along with a greater surface area for articulation at the joint amirite guys? Does it allow anything else? (eg would we say it is the structure of the menisci which allows slight (...rotation or abd/adduction?) of the flexed joint?)

It's a description of how stable the joint is - large contact area = good bony congruence = stable joint. Imagine two tennis balls on top of each other, is this a stable structure? No. Now imagine said tennis balls with a biconcave disc (meniscus) inbetween, which is much better.

 

[SeeKay]

Bony congruence is the sum of the bone surfaces which makes an articulation.

From my understanding, and to add to what's been said above, the LESS the bony congruence the more soft tissue support present in order to make the joint stable - which is where the meniscus comes in.

 

[Bluerock]

[MENTION=5278]Caesar[/MENTION], I'll post pictures of it to the study group page on facebook. Note it was the PE kid who did these answers and not me.

And my interpretation of bony congruence was how much bone touches bone. The knee joint has less bony congruence, and thus the fibrocartilage miniscue give some soft tissue support to the otherwise weak joint. This occurs by dispersing the same force over a larger area. That's how my lecture notes read.

 

[Ruth]

It's a description of how stable the joint is - large contact area = good bony congruence = stable joint. Imagine two tennis balls on top of each other, is this a stable structure? No. Now imagine said tennis balls with a biconcave disc (meniscus) inbetween, which is much better.

So could you say that the tennis balls now have better bony congruence with the meniscus then? Or would the low bony congruence mean there's a meniscus there, and because of that it's more stable?

 

[Cathay]

EDIT: This post tried to explain and got something wrong, so it has been wiped so as not to mislead others.

 

[greenglacier]

Menisci DON'T increase bony congruence. They're not bone, so they couldn't possible do that.

What menisci do (in part) is help to compensate for a lack of bony congruence.

 

[Cathay]

Ah, so I was wrong about that.

In fact, I've just gone and found the podcast of that lecture (which luckily I was too lazy to transfer to my hard drive that later died), and it would appear to prove me wrong and back gg up: "Bony congruence is the sum of bone surfaces that form an articulation. In the knee joint, there is relatively little congruence, so we need more soft tissue support. And you'll find that throughout the skeleton, wherever there is less bony congruence, there is more soft tissue to provide more stability. "

In fact, the lecturer goes on to say that if you think about the hip joint, where the femoral head (a round ball) is completely wrapped around by the socket of the hip bone, there's a lot of bony congruence there because there's a lot of bone meeting bone, meaning it needs less soft tissue support.

So to recap, as [MENTION=5278]Caesar[/MENTION] correctly pointed out, bony congruence is a result of articulation between bones only. Soft tissue structures such as menisci help make the joint more stable when there isn't much bony congruence, but as [MENTION=5161]greenglacier[/MENTION] pointed out, the soft tissue do not increase bony congruence.

PS: I was wrong in my assumption that "congruency = bony congruence" when I was reading Gray's about this matter. I apologize for this mistake, and will endeavour to find solid evidence before committing to an answer in the future. Sorry guys.

 

[sunny123]

Thanks for the clarification re menisci everyone

 

[sunny123]

erm...just for the calcutations to figure out tonicity of cells, how do we know that solutions are ionic and therefore will dissociate in water(haven't done chem since 5th form)..do we even need to know this or will it specifically be stated in questions?

also am i right in saying that calcium from the reticulum allows myosin and actin to interact?

thanks again guys

 

[alice]

erm...just for the calcutations to figure out tonicity of cells, how do we know that solutions are ionic and therefore will dissociate in water(haven't done chem since 5th form)..do we even need to know this or will it specifically be stated in questions?

also am i right in saying that calcium from the reticulum allows myosin and actin to interact?

thanks again guys

To answer your second question first, basically calcium DOES allow myosin and actin to interact, but I'd say it's important to understand the structure of myosin and actin so you can see that Calcium first binds to Troponin (which is only on the actin). Tropomyosin then moves to expose the actin binding sites to which myosin can attach (therefore causing the sarcomere to contract).

I had tried to answer the second but pretty sure I was incorrect when I read over it. But I think it's safe to say that if they do ask us to calculate tonicity/osmolarity whatever, the substance will be able to dissociate into ions

 

[Ruth]

erm...just for the calcutations to figure out tonicity of cells, how do we know that solutions are ionic and therefore will dissociate in water(haven't done chem since 5th form)..do we even need to know this or will it specifically be stated in questions?

Ionic substances are normally made up of a metal ion and a non-metal ion (eg. NaCl, PbCl2), but there's other ions like thiosulfate and phosphate, which I guess you just have to know? There's a chart in our Chem lab book of the common ions (altho the complex ions probably aren't gonna come up in hubs anyways)

 

[sunny123]

To answer your second question first, basically calcium DOES allow myosin and actin to interact, but I'd say it's important to understand the structure of myosin and actin so you can see that Calcium first binds to Troponin (which is only on the actin). Tropomyosin then moves to expose the actin binding sites to which myosin can attach (therefore causing the sarcomere to contract).

I had tried to answer the second but pretty sure I was incorrect when I read over it. But I think it's safe to say that if they do ask us to calculate tonicity/osmolarity whatever, the substance will be able to dissociate into ions

thanks very much for the clarification, i remember hearing that in the lec but didn't have time to note it down

Ionic substances are normally made up of a metal ion and a non-metal ion (eg. NaCl, PbCl2), but there's other ions like thiosulfate and phosphate, which I guess you just have to know? There's a chart in our Chem lab book of the common ions (altho the complex ions probably aren't gonna come up in hubs anyways)

thanks, i'm not doing chem lol(just hubs), i guess they'll tell us!

couple other q's:

Do we have to be able to identify things from pictures (e.g different bones/muscles/organs)..anything really?

Do we need to know about nerve supplies to different muscles? This wasn't covered in lecture 14 but was included in the readings to that lecture.

 

[Nimbus2000]

Do we have to be able to identify things from pictures (e.g different bones/muscles/organs)..anything really? Do we need to know about nerve supplies to different muscles? This wasn't covered in lecture 14 but was included in the readings to that lecture.

Hey sunny 1) No-one knows, (sorry, i know this answer is probably really unhelpful), but I am completely convinced that nobody on this forum, nor any student can know for sure whether there will be pictures asking us to identify the structures - that is based entirely on what the lecturers would like to do. So the only way to find out, is ask one of the lecturers? BUT, I highly doubt that they will give you an answer :S... From memory, the structures that we learnt, often had descriptions about what they did/what they linked to etc... I think maybe just have a look at the pictures on the slides.
2) No we don't (thank god) ... that is if you're asking about nerve supply to each particular muscle that we learnt in Lecture 14... we only need to know about the general idea of a nerve impulse (electric) being sent down the axons to the NMJ (where an unspecified chemical exchange/signal occurs) which then goes into the muscle as an electric impulse and stimulates the actin myosin blah blah blah... actually, she only told us to know the various areas that the electrical signals convert to a chemical signal and then convert to an electrical signal again.

Hope that answers your question