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    (Original post by jam277)
    I need help in the brain bit. What are the main things that we need to know for the CT, MRI and fMRI scanning?
    CT:
    -uses X-rays
    -produces cross-section images of the brain
    -different densities of tissue absorb different amounts of radiation and show up as different colours
    -shows major structures in the brain without much detail
    -used to tell the extent of an abnormality and its location in the brain
    -loss of a function may be associated with the abnormality seen

    MRI:
    -uses radio waves
    -cross-section images
    -tissues seen in much more detail
    -extent of abnormality and location
    -loss of a function may be associated with the abnormality seen

    fMRI:
    -like MRI but show changes in brain activity as they happen
    -more oxygenated blood flows to active brain areas, these areas show up in a different colour
    -identify parts of the brain associated with a function whilst it is performed in the scanner
    -study diseases caused by abnormal brain activity rather than structure


    :awesome: CGP
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    (Original post by whizz-kid)
    thats wat i thought aswell arent they
    introns are transcribed but they're not translated... introns are cut out of mRNA during splicing..
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    you are welcome
    Attached Files
  1. File Type: rtf Homeostasis questions.rtf (1.06 MB, 361 views)
  2. File Type: rtf Homeostasis ms.rtf (19.1 KB, 105 views)
  3. File Type: rtf Muscle & Joints questions.rtf (1.28 MB, 1317 views)
  4. File Type: rtf Muscle & Joints ms.rtf (24.8 KB, 117 views)
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    (Original post by whizz-kid)
    thats wat i thought aswell arent they
    Yeah I'm pretty sure they are.

    (Original post by memomemootoo)
    ...
    Omgg thank you sooo much for the muscle questions. I've been looking for some for so long and I couldn't find them. Where did you find them, if you don't mind me asking.
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    what do we have to know about action potentials? orange book is making it too confusing
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    Think of an mRNA sequence as a magazine..... a magazine has got useless advertisements that no one reads (the introns) and the articles that are read (exons).....

    Introns have to be transcribed and they are spliced out by protein complexes in post transcriptional modification
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    (Original post by InItToWinItGetIt?)
    Omgg thank you sooo much for the muscle questions. I've been looking for some for so long and I couldn't find them. Where did you find them, if you don't mind me asking.
    you are welcome)) ...my kind school gave them me ...also, if you're desperate for questions on any other topics let me know and i'll try to upload them aswell...
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    Revising won't help for these exams, there are just going to be some bull**** questions which are ambiguous and require no biological knowledge, in unit 4 they asked you to guess whether you think prescriptions for antibiotics will go below a certain number, and they gave you 4 sets of points which gave a weak negative correlation... FOR 3 MARKS!
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    (Original post by memomemootoo)
    you are welcome)) ...my kind school gave them me ...also, if you're desperate for questions on any other topics let me know and i'll try to upload them aswell...
    Have you got any on the role nature/nurture on the brain? Knowing edexcel they will throw up a ton of waffle.
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    (Original post by Engineer31)
    Revising won't help for these exams, there are just going to be some bull**** questions which are ambiguous and require no biological knowledge, in unit 4 they asked you to guess whether you think prescriptions for antibiotics will go below a certain number, and they gave you 4 sets of points which gave a weak negative correlation... FOR 3 MARKS!
    Lol totallllyy! I f0und the Wavelength Q ridiculous!

    *Sigh* .. But just can't sit around Doing nothing :/

    Article help needed!
    Any1n?
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    (Original post by jklm123)
    what do we have to know about action potentials? orange book is making it too confusing
    firstly, this is how depolarisation happens:
    stimulus arrives
    soduim channels in the cell membrane open
    sodium ions flow in
    the inside of the cell become increasingly positive
    more sodium ion channels open
    the cell is then depolarised up to around +45mV
    sodium channels close and potassium channels open
    potassium ions exit the cell causing it to become increasingly negative
    hyperpolarisation occurs (also known as the refractory period, time is needed for the cation channels to close...)
    the resting potential of -70mV is then reached

    ...in action potentials the sodium ions at the start diffuse sideways causing the area of depolarisation to move across the axon

    also you need to know this:
    -when the cell is at rest the resting potential is reached by pumping out 3 sodium ions for every 2 potassium ions which enter
    -the action potentials are unidirectional and discrete due to the refractory period
    -saltatory conduction happens in myolinated axons where depolarisation can only occur at the nodes of ranvier (where sodium channels are situated)
    -saltatory conduction is faster than what happens in non-myolinated neurones
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    (Original post by jklm123)
    what do we have to know about action potentials? orange book is making it too confusing
    We have to know how they're caused, all the stages, depolarisation, repolarisation, hyperpolarisation and restoring resting potential. I once saw a question where you had to identify the stages from a graph of Voltage and time. Try to remember whether the Na or K channels are open, that comes up quite regularly.
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    hey guys..how s everybody preparing 4 the paper? anybody have any notes or something for the article?
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    (Original post by InItToWinItGetIt?)
    Have you got any on the role nature/nurture on the brain? Knowing edexcel they will throw up a ton of waffle.
    do you mean the stuff on habituation and cute little kittens with sewn up eyes?

    if yes then i've got some questions but they're too heavy to upload on here... i can try sending them to your email if you like..?
    Attached Files
  5. File Type: rtf Nervous system ms.rtf (139.1 KB, 114 views)
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    (Original post by memomemootoo)
    CT:
    -uses X-rays
    -produces cross-section images of the brain
    -different densities of tissue absorb different amounts of radiation and show up as different colours
    -shows major structures in the brain without much detail
    -used to tell the extent of an abnormality and its location in the brain
    -loss of a function may be associated with the abnormality seen

    MRI:
    -uses radio waves
    -cross-section images
    -tissues seen in much more detail
    -extent of abnormality and location
    -loss of a function may be associated with the abnormality seen

    fMRI:
    -like MRI but show changes in brain activity as they happen
    -more oxygenated blood flows to active brain areas, these areas show up in a different colour
    -identify parts of the brain associated with a function whilst it is performed in the scanner
    -study diseases caused by abnormal brain activity rather than structure


    :awesome: CGP
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    (Original post by memomemootoo)
    do you mean the stuff on habituation and cute little kittens with sewn up eyes?

    if yes then i've got some questions but they're too heavy to upload on here... i can try sending them to your email if you like..?
    I've got questions on those I think. I meant like, the role of twin studies, people with damaged brains etc.

    Thanks for offering the other questions though, very nice of you.
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    Hey guys, which practicals do we need to know?

    Thanks x
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    (Original post by samima1)
    hey guys, which practicals do we need to know?

    Thanks x
    habituation, spirometer, respirometer
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    (Original post by darkiee)
    habituation, spirometer, respirometer
    Thanks!!
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    guys anything for the article pleeeeeeeeeease!
 
 
 
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