ATAR Notes: Forum
Uni Stuff => Universities - Victoria => University of Melbourne => Topic started by: Turtle on September 02, 2013, 05:32:34 pm
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Hey all,
Since the PHYS20008 mid sem is coming up, I thought I'd create a question thread :) Hope it helps you all!
I'll start it off...
I am having serious issues understanding this...What is the difference between pre-synaptic inhibition and post-synaptic inhibition?
The lecture notes don't explain it very well!
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Hey Turtle!
This is a good idea. Are you thinking of doing past papers in preparation too, there are some tricky questions on that we could look at too.
One of the textbooks (sherwoood or silverthorn) goes through it pretty well. I think I used silverthorn. Presynaptic inhibition is when an inhibitory neuron directly synapses on say, one axon termial of a presynaptic neuron. So say there are 3 axon terminals, one is modulated such that it will not release a neurotransmitter thus there will be no response in the target cell and the other 2 since they have not been directly affected can still release neurotransmitter and there is a response for those target cells. That's the way I understand it but i'm not sure if it's entirely correct. Postsynaptic inhibition is to do with summation of the signals generated by inhibitory and excitatory neurons. So here there is a postsynaptic cell which an inhibitory presynaptic neuron and an excitatory neuron both synapse to. The IPSP produced by the inhibitory neuron exerts the dominant effect such that the EPSP produced by the excitatory neuron (remembering it's a gp) is not of high enough amplitude by the time it reaches the axon hillock to fire an action potential. Thus there is no action potential reaching the axon terminals which would cause it to release neurotransmitter. The target cells in this case for each axon terminal are all inhibited equally, and we would see no response in the target cell.
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Thanks El!!
Also, did anyone save last semesters PHYS20008 MST?
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How did you find MST2?
When did you guys say the SL valves closed, end of t wave? I had no idea
and for the question 1 does cutting the vagus nerve reduce gastric motility in response to distension or was it the one about the initial phases of the stimuli? If it was the latter i'm wrong.
Was the last question about clearance to clear Na+ out of the plasma??
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How did you find MST2?
When did you guys say the SL valves closed, end of t wave? I had no idea
and for the question 1 does cutting the vagus nerve reduce gastric motility in response to distension or was it the one about the initial phases of the stimuli? If it was the latter i'm wrong.
Was the last question about clearance to clear Na+ out of the plasma??
I found it okay. It was a little harder than the 1st mid sem.
I said the same as you for the SL valve question, so that is a good start :)
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I found it okay. It was a little harder than the 1st mid sem.
I said the same as you for the SL valve question, so that is a good start :)
Haha I assume I got all the other stuff wrong
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I don't expect to do well lol. I've been feeling so light-headed this whole week I can barely keep my head up let alone concentrate enough to study/do a test. Where's that baroreceptor reflex when you need it most? No wonder I've been craving salt lately. Hahah.
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I don't expect to do well lol. I've been feeling so light-headed this whole week I can barely keep my head up let alone concentrate enough to study/do a test. Where's that baroreceptor reflex when you need it most? No wonder I've been craving salt lately. Hahah.
I might have seen you today BelVP but i'm not sure. Do you have a fringe by any chance?
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I might have seen you today BelVP but i'm not sure. Do you have a fringe by any chance?
Fringe yes. & I look obviously anemic.
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Fringe yes. & I look obviously anemic.
Were you on the left hand side of the lecture theatre, towards the front and wearing black?
Yep that should narrow it down haha
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I found it okay. It was a little harder than the 1st mid sem.
I said the same as you for the SL valve question, so that is a good start :)
I put that one too!!
But honestly the last 18 mins or something was crazy for me. I really want to kick myself for spending so much time on the digestion and cardiovascular questions. I didn't really have time to think through some of the kidney questions. :(
I actually thought it was a lot harder than the first.
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Yeah you're right.
When did you guys say the SL valves closed, end of t wave? I had no idea
Assuming SL is semi lunar, that's right.
and for the question 1 does cutting the vagus nerve reduce gastric motility in response to distension or was it the one about the initial phases of the stimuli? If it was the latter i'm wrong.
Vagus nerve acts to stimulate gastric emptying, loss will reduce contractions/motility.
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Were you on the left hand side of the lecture theatre, towards the front and wearing black?
Yep that should narrow it down haha
Yep xD
Ah well. I got a H1 in the first MST which will hopefully compensate.
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I guess results won't be coming out today :/
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I really want mine back :( The anticipation is killing me!
I almost fainted with grade centre had 3 grade notifications.
I also really want my research based phys report back!
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Hopefully they will be released before the revision session on Monday. It would be great to have a chance to go through the questions before then :)
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Hopefully they will be released before the revision session on Monday. It would be great to have a chance to go through the questions before then :)
I agree. Welcome to AN btw neatfeet :)
I really want mine back :( The anticipation is killing me!
I almost fainted with grade centre had 3 grade notifications.
I also really want my research based phys report back!
Haha don't think we will get research back until mid next-week at the earliest, just my predictions.
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I agree. Welcome to AN btw neatfeet :)
Thanks El :)
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I think there might be some resonant grade centre issues because in our class on Thursday our lecturer was going through 'what questions people got wrong on the MST' but our grades are still not up...haha.
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I think there might be some resonant grade centre issues because in our class on Thursday our lecturer was going through 'what questions people got wrong on the MST' but our grades are still not up...haha.
Hm yeah maybe they aren't bothering to put the grades up until they know grade centre is working 100%
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hgkjasdbksadbdskb please can we get out physiology results back NOW.
Why is it taking soo longgggg!
I keep seeing updates on the physiology facebook page that have nothing to do with results aaaarghhgh
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I really want mine back :( The anticipation is killing me!
I almost fainted with grade centre had 3 grade notifications.
I also really want my research based phys report back!
Research results won't come out till after exams.. at least thats was how it was last semester
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Research results won't come out till after exams.. at least thats was how it was last semester
Did they give you the actual mark for the research report or was it just integrated into the final subject mark?
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Did they give you the actual mark for the research report or was it just integrated into the final subject mark?
They will give you the mark for the report as well as it being broken down into its sections to show like where you lost marks.
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El, I think they are manually releasing the results right now. I've got this nice juicy red "1" sitting on the grade centre icon but when I click it nothing comes up. But in the updates it says that my grade for #2 midsem has been updated. :/
Don't know what's going on, but I think I'll wait till Charles puts up a formal notification saying its up so I'm sure this is my actual mark.
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El, I think they are manually releasing the results right now. I've got this nice juicy red "1" sitting on the grade centre icon but when I click it nothing comes up. But in the updates it says that my grade for #2 midsem has been updated. :/
Don't know what's going on, but I think I'll wait till Charles puts up a formal notification saying its up so I'm sure this is my actual mark.
I'm hoping it is. If so I passed. Could have done better but my other marks should make up for it.
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BelVP, looking at the range of marks, a pass is really good!
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I got 25/30, same as last time :o
This test was harder guys, I wouldn't compare your marks too much to the previous ones.
I know someone who got 22/30 on this one, and ended up with 93 in Phys, so if you aren't happy with your mark, don't take it too much to heart!
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I got 25/30, same as last time :o
This test was harder guys, I wouldn't compare your marks too much to the previous ones.
I know someone who got 22/30 on this one, and ended up with 93 in Phys, so if you aren't happy with your mark, don't take it too much to heart!
I'm sure they did incredibly well on the first mid semester test though. Unfortunately for me, it doesn't really apply in my case.
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At least you improved El. And I don't think it's your study method. It must have been the exam which was harder than the first.
But I understand your frustration. I went down by 3. And I put in the same effort I did for the first one. I have to blame my exam technique. It's like a billion times I've heard the advice "don't spend too much time on any question that you are struggling with, skip and come back to it later" but when I'm in the exam I totally forget it and waste so much of time. Oh well! Gonna work on that for the exam.
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I know i'll sound incredibly stupid in writing this. But I just want to clarify, that in the exam there will be absolutely NO questions which require a written paragraph but they are entirely ALL questions which utilize multiple choice answer sheets (A-D or A-Z) ? ? ?
I don't want to go into the exam and be caught by surprise by anything.
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There are none El :) I'm not sure what to think about that..
I kind of like just regurgitating information, that's what I'm best at :o
I wouldn't say I'm the best thinker in the world!
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I studied much more for this mid-sem and ended up with the same mark I got for the 1st one :( Gah!
Pink, I have trouble with that too! Except that when I don't know the answer to a question, I leave it straight away and continue with the rest of the paper. Then once I've answered all the questions I do know, there's less than 10 minutes left and I don't have time to work through the ones I left as thoroughly as I would like to! asdfghjkl.
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Welcome to ATAR notes neatfeet!! ;D
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Pink, I have trouble with that too! Except that when I don't know the answer to a question, I leave it straight away and continue with the rest of the paper. Then once I've answered all the questions I do know, there's less than 10 minutes left and I don't have time to work through the ones I left as thoroughly as I would like to! asdfghjkl.
That happens to me too! And sometimes I skip the questions, do the easy ones fast and come back to the hard ones. But then I'm so careless I end up losing marks are the easy ones!! >:(
But I think we did well overall guys The average improved from last sem!
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BelVP, looking at the range of marks, a pass is really good!
Hahah yeah x) Was worried I'd failed since I was terribly anemic that week and had some personal problems (partner is hospital). Did about average though.
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Hahah yeah x) Was worried I'd failed since I was terribly anemic that week and had some personal problems (partner is hospital). Did about average though.
I know the tiredness that comes with anemia!! I had it for a year!
Iron tablets fixed me up quickly though!
Hope you feel better soon :) sorry to hear about your partner :(
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Ugh, also a sufferer of anaemia at one stage in my life- fainted one time, yeah that wasn't fun. But yeah as turtle said, definitely recommend iron tablets as the most practical treatment.
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Hahah GUYYSS.... I'm anaemic too!!! I know how it feels since I had it throughout 1st year of uni :( This year is much better
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I'm on iron tablets but don't absorb it well at all >_<
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For anyone doing Research Based Phys (PHYS20009), I wonder when we will get our marks back for the Thermoreg report?
It says that the post date is tomorrow, so perhaps we might get them back then?
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For anyone doing Research Based Phys (PHYS20009), I wonder when we will get our marks back for the Thermoreg report?
It says that the post date is tomorrow, so perhaps we might get them back then?
Someone said (I think it was seretide) that for last semester they received their results for thermoreg after the exam
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Someone said (I think it was seretide) that for last semester they received their results for thermoreg after the exam
I hope not!! Deanne told us that they would hopefully come back during SWOTVAC. Hopefully they have changed it from last year :/
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I'm on iron tablets but don't absorb it well at all >_<
If you're not a massive meat eater, maybe try some other iron-enriched foods :)
I know weet bix has 25% of your daily iron intake and there's also iron-enriched soy milk. Together they can give up to 50% of your daily intake.
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If you're not a massive meat eater, maybe try some other iron-enriched foods :)
I know weet bix has 25% of your daily iron intake and there's also iron-enriched soy milk. Together they can give up to 50% of your daily intake.
Sorry to butt in but Spinach is good too! :D
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Spinach is actually not good at all, the majority of its iron is in a form not readily absorbable by our body - it turns out to be, nutrition-wise, a pretty poor source of iron compared to other foods.
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Spinach is actually not good at all, the majority of its iron is in a form not readily absorbable by our body - it turns out to be, nutrition-wise, a pretty poor source of iron compared to other foods.
Probably not the most convenient source either, consulted a doctor about it and he said you need to it bushes of it for it to have it's effect.
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Probably not the most convenient source either, consulted a doctor about it and he said you need to it bushes of it for it to have it's effect.
You learn something new everyday! :0 I do eat quite a bit though xD
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Spinach is still a good food to eat :3 and nice in salads :D
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Hey, was just wondering if anyone has started any past exams for physiology?
There was a few questions I had about some of the ones on the kidneys...
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Just post questions, people will answer them anyway :P
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I was having a bit of trouble with the kidney hormones and was wondering if anyone could help me out with the following (check if these are correct?)
a) Increase in ECF osmolarity, increase in ECF volume= Decrease aldosterone (to decrease ecf osm), increase vasopressin? (prioritising ecf osmolarity)
b) Decrease ECF osmoalrity, increase ECF volume= Increase aldosterone (increase ecf osm), decrease vasopressin (eliminate excess h2O)
c) Increase ECF osmolarity, decrease ECF volume= decrease aldosterone, increase vasopressin
d) Decrease ECF osmolarity, increase ecf volume= increase aldosterone, decrease vasopressin
I was most confused about a. There is the stimulus for increasing ECf osmolarity which is a stimulus for increasing vasopressin release, however an increase in ecf volume is supposed to decrease vasopressin release :/
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bump?
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Hey El, sorry, I haven't look at Physiology much yet.
Just focussing on Pathology at the moment.
I'll answer after Pathology :)
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PHYS20009 Thermoreg report comments are on our assignments!
But strangely, no marks hahaha...
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I've got my marks back for thermoreg turtle :O
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I'm checking now...This better not screw me up for pathology haha!!
Lets see what I got :/
Edit: I got 87% so I'm fairly happy with that :)
It makes handing in all the drafts worth it!
Judging by your " :O " I assume your mark was really good?! I hope you were happy with it!!
Good luck for Pathology too!! :)
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I got a reaaaally really horrible mark in one of my sections which i dont think is right, i expected a lil higher, (i even got better in another section which was actually horrible!), can I email them? its weird because supervisors actually read through them before its released to ensure the appropriate mark is given .. :/
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I got a reaaaally really horrible mark in one of my sections which i dont think is right, i expected a lil higher, (i even got better in another section which was actually horrible!), can I email them? its weird because supervisors actually read through them before its released to ensure the appropriate mark is given .. :/
Yes definatly email them. I got given an N on one of my pracs because their computer system stuffed up and said I didn't hand it in when I did.
A quick email, and 4 hours later, they gave me an H1.
Its clear from my situation that they make mistakes, and I see no harm by emailing them :)
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Edit: I got 87% so I'm fairly happy with that :)
It makes handing in all the drafts worth it!
Judging by your " :O " I assume your mark was really good?! I hope you were happy with it!!
84.5 :)
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84.5 :)
Yes!!!!! well done El!!!!!!
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Yes!!!!! well done El!!!!!!
Thanks :) Great effort on your mark too
Just want to do really well on the exam now!!
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is Tidal volume:
total lung capacity - inspiratory reserve volume - expiratory reserve volume ORRRR total lung capacity - inspiratory reserve volume - functional residual capacity
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For Physiology, we have to know this according to Charles:
"What are the structural differences to a neurone-neuron synapse, that allow it to have a 1-1 AP ratio?".
I know that the motor end plate has folds, which increases the SA, meaning there are more nicotinic receptors for acetylcholine.
But what are the other structural differences?
Also, I don't really get allow this means that there is a 1-1 AP ratio, unlike a neuron-neuron synapse?
Can someone explain this to me? thanks :)
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I'm pretty sure it's the latter.
If it were TV=TLC-IRV-ERV, you wouldn't be taking into account the residual volume of air left in the lungs. Another way of calculating TV is vital capacity - IRV - ERV. There's a handy diagram on slide 20 of the 2nd respiration lecture that outlines this.
Hope that helps :)
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For Physiology, we have to know this according to Charles:
"What are the structural differences to a neurone-neuron synapse, that allow it to have a 1-1 AP ratio?".
I know that the motor end plate has folds, which increases the SA, meaning there are more nicotinic receptors for acetylcholine.
But what are the other structural differences?
Also, I don't really get allow this means that there is a 1-1 AP ratio, unlike a neuron-neuron synapse?
Can someone explain this to me? thanks :)
These kinds of questions confuse me because I don't know how they can be integrated into a fill in the blanks type question :S
1-1 means when a motor neuron fires an action potential there's always going to be a contraction in the muscle fibre that it innervates.
A few reason's as to why this is the case:
- Corregations on the muscle fibre provide a high surface area which has many different neurotransmitter receptor-channels that acetylcholine can bind to
- There is lots more acetylcholine which is stored in the alpha motor neuron than neurotransmitter storage in a presynaptic neuron
- More receptor channels on the muscle membrane are opened up in response to an acton potential in an alpha motor neuron which means there is a greater rate of depolarization occuring than in a presynaptic neuron-> muscle fibre always reaches threshold -> always fires an action potential in response to an alpha motor neuron firing
Neuron-neuron synapse may not always have the post synaptic neuron having it's graded potential reaching threshold at the trigger zone therefore may not fire action potentials
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These kinds of questions confuse me because I don't know how they can be integrated into a fill in the blanks type question :S
1-1 means when a motor neuron fires an action potential there's always going to be a contraction in the muscle fibre that it innervates.
A few reason's as to why this is the case:
- Corregations on the muscle fibre provide a high surface area which has many different neurotransmitter receptor-channels that acetylcholine can bind to
- There is lots more acetylcholine which is stored in the alpha motor neuron than neurotransmitter storage in a presynaptic neuron
- More receptor channels on the muscle membrane are opened up in response to an acton potential in an alpha motor neuron which means there is a greater rate of depolarization occuring than in a presynaptic neuron-> muscle fibre always reaches threshold -> always fires an action potential in response to an alpha motor neuron firing
Neuron-neuron synapse may not always have the post synaptic neuron having it's graded potential reaching threshold at the trigger zone therefore may not fire action potentials
I was wondering about this too. El, what you've said sounds pretty good to me :) Not sure if this is on the right track, but does it also have something to do with each muscle fibre being innervated by a single alpha motor neuron, meaning that there are no inhibitory neurons that can patch on to the alpha motor neuron and inhibit the release of AcH?
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I was wondering about this too. El, what you've said sounds pretty good to me :) Not sure if this is on the right track, but does it also have something to do with each muscle fibre being innervated by a single alpha motor neuron, meaning that there are no inhibitory neurons that can patch on to the alpha motor neuron and inhibit the release of AcH?
I'm pretty sure this is the case for the golgi tendon reflex though, the alpha motor neuron is inhibited as a result of an inhibitory neuron in the spinal cord. For example a person with their eyes closed and all of a sudden you drop a load in their hand, the person will drop the load in order to protect their muscle fibres from being damaged.
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I was having a bit of trouble with the kidney hormones and was wondering if anyone could help me out with the following (check if these are correct?)
a) Increase in ECF osmolarity, increase in ECF volume= Decrease aldosterone (to decrease ecf osm), increase vasopressin? (prioritising ecf osmolarity)
b) Decrease ECF osmoalrity, increase ECF volume= Increase aldosterone (increase ecf osm), decrease vasopressin (eliminate excess h2O)
c) Increase ECF osmolarity, decrease ECF volume= decrease aldosterone, increase vasopressin
d) Decrease ECF osmolarity, increase ecf volume= increase aldosterone, decrease vasopressin
I was most confused about a. There is the stimulus for increasing ECf osmolarity which is a stimulus for increasing vasopressin release, however an increase in ecf volume is supposed to decrease vasopressin release :/
does anyone know this one
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I'm pretty sure this is the case for the golgi tendon reflex though, the alpha motor neuron is inhibited as a result of an inhibitory neuron in the spinal cord. For example a person with their eyes closed and all of a sudden you drop a load in their hand, the person will drop the load in order to protect their muscle fibres from being damaged.
Thanks El :)
does anyone know this one
Okay, so I just typed out the pathways responsible for this when I finally understood your question lol. Because there are 2 pathways at work (one that responds to increased osmolarity and another that responds to increased blood volume) they would balance each other out. So vasopressin levels would remain the same....I think....
Please correct me if I'm wrong. The urinary system makes me want to repeatedly headdesk.
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Thanks El :)
Okay, so I just typed out the pathways responsible for this when I finally understood your question lol. Because there are 2 pathways at work (one that responds to increased osmolarity and another that responds to increased blood volume) they would balance each other out. So vasopressin levels would remain the same....I think....
Please correct me if I'm wrong. The urinary system makes me want to repeatedly headdesk.
Haha. I think aldosterone levels when definitely decrease because of the increase in Osm, as far as I can tell- that has been taught as a direct inhibitory mechanism. I think gaby said that it has to be a major decrease in volume to increase vasopressin so I imagine an increase in ecf volume wouldn't do all that much to vasopressin levels (i.e. decrease them) if there was an increase in ecf osmolarity (prioritise the latter).
Lol this was never an exam question, I think I just decided to make up a really tricky one. I think i'll stick by what I have said for a, it just makes more sense to me that we would priortisie increase in ecf osm to increase vasopressin release over decreasing it due to an increase in ecf volume.
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Haha. I think aldosterone levels when definitely decrease because of the increase in Osm, as far as I can tell- that has been taught as a direct inhibitory mechanism. I think gaby said that it has to be a major decrease in volume to increase vasopressin so I imagine an increase in ecf volume wouldn't do all that much to vasopressin levels (i.e. decrease them) if there was an increase in ecf osmolarity (prioritise the latter).
Lol this was never an exam question, I think I just decided to make up a really tricky one. I think i'll stick by what I have said for a, it just makes more sense to me that we would priortisie increase in ecf osm to increase vasopressin release over decreasing it due to an increase in ecf volume.
Just checked my notes and I've noted that osmolarity is prioritised over volume. Probably should have checked that before I answered haha!
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These kinds of questions confuse me because I don't know how they can be integrated into a fill in the blanks type question :S
1-1 means when a motor neuron fires an action potential there's always going to be a contraction in the muscle fibre that it innervates.
A few reason's as to why this is the case:
- Corregations on the muscle fibre provide a high surface area which has many different neurotransmitter receptor-channels that acetylcholine can bind to
- There is lots more acetylcholine which is stored in the alpha motor neuron than neurotransmitter storage in a presynaptic neuron
- More receptor channels on the muscle membrane are opened up in response to an acton potential in an alpha motor neuron which means there is a greater rate of depolarization occuring than in a presynaptic neuron-> muscle fibre always reaches threshold -> always fires an action potential in response to an alpha motor neuron firing
Neuron-neuron synapse may not always have the post synaptic neuron having it's graded potential reaching threshold at the trigger zone therefore may not fire action potentials
Thanks El!!
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I found something else that we need to know for the exam according to Charles: "*For exam, how do skeletal muscles and cardiac muscles differ in terms of AP and EC coupling?".
I understand how they differ in terms of action potential generation/spread etc...
But, I don't quite understand what he means in terms of EC coupling? Or how they differ? Because it is not in the notes clearly..
Can anyone help me?
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Also, just going back through a few key PRS questions...I came across this one:
Removing ECF calcium would prevent which of the following cells from firing an action potential when stimulated directly?
1. Neurons
2. Skeletal muscle cells
3. Cardiac autorhythmic cells
4. Cardiac contractile cells
5. Smooth muscle cells
Apparently 3 and 5 is the answer.
I understand why 1 and 2, and 4 would be fine if they were stimulated directly.
And I understand why 3 would not be able to fire an action potential.
However, why wouldn't 5 be able to fire it were stimulated directly, even if the ECF Ca2+ was removed?
Smooth muscle cells have a sarcoplasmic reticulum, which releases calcium...so this doesn't make sense?
I am obviously very confused somewhere!
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Also, just going back through a few key PRS questions...I came across this one:
Removing ECF calcium would prevent which of the following cells from firing an action potential when stimulated directly?
1. Neurons
2. Skeletal muscle cells
3. Cardiac autorhythmic cells
4. Cardiac contractile cells
5. Smooth muscle cells
Apparently 3 and 5 is the answer.
I understand why 1 and 2, and 4 would be fine if they were stimulated directly.
And I understand why 3 would not be able to fire an action potential.
However, why wouldn't 5 be able to fire it were stimulated directly, even if the ECF Ca2+ was removed?
Smooth muscle cells have a sarcoplasmic reticulum, which releases calcium...so this doesn't make sense?
I am obviously very confused somewhere!
Smooth muscle also uses the calcium-dependent calcium coupling... See page 429 of 6th edition Silverthorn "an increase in cytosolic Ca initiates contraction..." hehe
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I found something else that we need to know for the exam according to Charles: "*For exam, how do skeletal muscles and cardiac muscles differ in terms of AP and EC coupling?".
I understand how they differ in terms of action potential generation/spread etc...
But, I don't quite understand what he means in terms of EC coupling? Or how they differ? Because it is not in the notes clearly..
Can anyone help me?
In line with what I posted just now, skeletal muscle needs acetylcholine to initiate contraction. Cardiac muscles need ECF Ca+...
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In line with what I posted just now, skeletal muscle needs acetylcholine to initiate contraction. Cardiac muscles need ECF Ca+...
Thanks Crescendo!
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For anyone who did PHYS20009, lets pray for a question on Restrictive vs. Obstructive lung diseases haha!
I will cry with joy if that appears on the exam, because we all know is so well know after spending so much time on it!
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For anyone who did PHYS20009, lets pray for a question on Restrictive vs. Obstructive lung diseases haha!
I will cry with joy if that appears on the exam, because we all know is so well know after spending so much time on it!
Agreed! The respiration stuff came quite naturally for me because I had already learnt nearly half of it before! :)
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Ok, I am still having serious issues with one area on muscles.
For smooth muscles:
If we remove ECF Ca2+, but still stimulate the muscle, shouldn't it be able to fire?
Because it has a sarcoplasmic reticulum that releases calcium itself.
I don't understand how a cardiac muscle can fire when stimulated directly, while a smooth muscle cannot.
Cardiac muscles also have Ca2+ dependant Ca2+ release from the SR, just like smooth muscles?
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Ok, I am still having serious issues with one area on muscles.
For smooth muscles:
If we remove ECF Ca2+, but still stimulate the muscle, shouldn't it be able to fire?
Because it has a sarcoplasmic reticulum that releases calcium itself.
I don't understand how a cardiac muscle can fire when stimulated directly, while a smooth muscle cannot.
Cardiac muscles also have Ca2+ dependant Ca2+ release from the SR, just like smooth muscles?
Yea, I'm a bit confused too. I think it has something to do with the rising phase of the action potential for cardiac contractile cells being Na+ dependent.
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Ok, I am still having serious issues with one area on muscles.
For smooth muscles:
If we remove ECF Ca2+, but still stimulate the muscle, shouldn't it be able to fire?
Because it has a sarcoplasmic reticulum that releases calcium itself.
I don't understand how a cardiac muscle can fire when stimulated directly, while a smooth muscle cannot.
Cardiac muscles also have Ca2+ dependant Ca2+ release from the SR, just like smooth muscles?
In smooth muscles, the Ca2+ in the sacroplasmic reticulum is only released as a result of calcium-induced calcium release due to an influx of Ca2+ from the ECF. This stands in contrast to skeletal muscle cells in which the DHP receptors in the t-tubules are mechanically linked to the calcium release channels in the sarcoplasmic reticulum (i.e. no calcium-induced calcium release). As such, ECF Ca2+ is required for smooth muscle contraction.
In addition, smooth muscle action potentials use Ca2+ instead of Na+ for depolarization, so if you remove ECF Ca2+ action potentials won't be able to fire in the first place, even if the cells are directly stimulated.
Now, cardiac contractile muscle cells also have calcium-induced calcium release. As such, their contraction requires ECF Ca2+, but the propagation of action potentials in these cells does not require ECF Ca2+.
Does that help...? I think part of the problem might be that you're forgetting to separate whether or not a given cell will be able to contract from whether a given cell will be able to fire an action potential.
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Easiest way to remember -> Depolarization of Smooth muscle cells & cardiac autorhythmic cells depends on calcium
Depolarization of calcium= SMAC (SM= Smooth muscle AC= autorhythmic cardiac) the mechanisms will only confuse you.
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Did you guys learn anything about smooth muscle action potentials in phys? I read somewhere that the rising phase is actually due to Ca2+ influx but we didn't learn it in our course and i think i recall seeing it in one of your past exams.
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Did you guys learn anything about smooth muscle action potentials in phys? I read somewhere that the rising phase is actually due to Ca2+ influx but we didn't learn it in our course and i think i recall seeing it in one of your past exams.
No we didn't have a diagram with a rising phase or anything but it's definitely good to know. We only learnt about excitation-contraction coupling.
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No we didn't have a diagram with a rising phase or anything but it's definitely good to know. We only learnt about excitation-contraction coupling.
I'm pretty sure that Charles did actually mention it in the lecture though (even though it's not on the slides).
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I'm pretty sure that Charles did actually mention it in the lecture though (even though it's not on the slides).
I'm pretty sure we would only need to know about the depolarization of the AP cycle for smooth muscle in that case
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I'm pretty sure we would only need to know about the depolarization of the AP cycle for smooth muscle in that case
Everything else is the same as a "standard" action potential anyway =)
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Everything else is the same as a "standard" action potential anyway =)
Cool, thanks! :)
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No matter how much I study for this exam I feel like I'm going to screw up anyway. :( I'm definitely going to get confused when it comes to those extended matching response type questions. I don't understand why but when I see all those answers on the page my brain goes all asdnasndaijnsdjnasikjcnjrbf... I would much rather have short answer questions :-[
Anyway Good luck with the exam tomorrow guys!! And El good luck with Genes and genomes too- smash both of them ;)
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No matter how much I study for this exam I feel like I'm going to screw up anyway. :( I'm definitely going to get confused when it comes to those extended matching response type questions. I don't understand why but when I see all those answers on the page my brain goes all asdnasndaijnsdjnasikjcnjrbf... I would much rather have short answer questions :-[
Anyway Good luck with the exam tomorrow guys!! And El good luck with Genes and genomes too- smash both of them ;)
You'll do great pink0829, if you feel a bit nervous just shake them out a little bit (lol I did that in one of my exams) but it worked. Remember charles mentioned that these questions are decided to test your thinking and if you can't process a question the first time then that's fine, just read it again until you understand what it is saying. Maybe you might want to try leaving the extended matching questions last in that case, always good to get the easiest stuff done first. And thanks so much! :) All the best to you guys too.
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How did we do? I didn't like the respiration one with the hose, I was confused was it supposed to resemble an obstructive lung disease? If so then it should have been written saying that.
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I liked that exam quite a lot!
I hated the question with the hose too...
I loved all the questions on muscles, and all the questions on the kidneys.
I was a tad disappointed that there was nothing on the baroreceptor reflex!
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Well that was a bit hard. I kinda expected it would be because last sem was apparently really easy.
Yeah, what was with that pool question?!? Some of the kidney questions were a bit hard for me to figure out but the rest wasn't too bad.
The muscle, digestive system, reproduction and nerve questions were really good and the respiration multiple choice questions were nice to me :)
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Did you guys treated the decrease in blood volume as an increase in blood pressure? Even though the osmolarity stayed the same..
I hope that was right, because it threw me off a bit!
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I thought that if blood volume drops -> pressure drops.. but I may be wrong. Kidney section was not my favourite part of phys.
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I said decrease in blood pressure too.. I think it was on the renin-angiotensin diagram..
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OOPS I MEAN DID YOU TREAT A DROP IN BLOOD VOLUME AS A DROP IN BLOOD PRESSURE.
embarrassing…awkward turtle :o
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OOPS I MEAN DID YOU TREAT A DROP IN BLOOD VOLUME AS A DROP IN BLOOD PRESSURE.
embarrassing…awkward turtle :o
lol I don't remember the question anymore, hope I went okay in it :S
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lol I don't remember the question anymore, hope I went okay in it :S
I referred to the Renin ANG diagram too, so hopefully we did it correctly!!
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Just saw this on LMS:
Final exam average: 68.5
Total subject average: 69.2 (edited .. . . . . .)
Subject outcomes:
H1: 27.6%
Apparently we've done better than the previous semester. Charles reeeeeeeeeeealllly likes us lol!
And we should expect our results by the end of the week (tomorrow??) according to the announcement.
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Considering I was too busy stressing over biochem the day before the physiology exam I am probably the idiot who brought down the average xD
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Hopefully it comes out today-this is the subject I'm more keen to find out my mark for!
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Hello beautiful, smart, funny, fascinating, classy and most importantly, generous and kind PHYS20008 students. Do any of you still have your lecture notes or any content related to PHYS20008, such as recommended textbook pages/tutorial PDFs/lectures from LMS? I was hoping to study Human Physiology over the holidays because I'm pulling more shifts next year at work and want to be able to juggle the courseload.
If anyone has material from cognitive psychology/research-based physiology/principles of human structure/biological psychology/compariative nutrition and digestion as well, you would make my life.