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    (Original post by flower123456)
    They may bring it up so its worth going over it.
    Thanks


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    (Original post by nukethemaly)
    Could someone please define oxidative stress?

    Oxidative stress is caused by an imbalance between the prodution of reactive oxygen and a biological system's ability to readily detoxify the reactive intermedidiates or easily repair the resulting damage.
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    (Original post by Zahra333)
    Heyyy this was a question that came up in the june 2010 paper.
    "Describe how the cardiovascular centre, in the medulla oblongata, affects the SAN during exercise."

    the answer was
    That increased impulses sent via the sympathetic nervous system to the SAN which stimulates frequent depolarisation which in turn increases the heart rate.

    Does that help?
    Yes I saw that one and it is helpful so thank you
    However I was wondering about where the chemoreceptors are for the heart rate control and the breathing rate control :/
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    (Original post by thegreenchildren)
    Yes I saw that one and it is helpful so thank you
    However I was wondering about where the chemoreceptors are for the heart rate control and the breathing rate control :/
    They're in the carotid arteries and aortic arch, near the heart - I think the textbook has a diagram. There are some found in the medulla itself.
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    How do we use traces from a spirometer to compare the tidal volume and breathing rates of human female and male subjects? Does anyone have a complete answer for this?
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    (Original post by bubblegummer)
    How do we use traces from a spirometer to compare the tidal volume and breathing rates of human female and male subjects? Does anyone have a complete answer for this?
    calculate the amplitude to find the tidal volume.
    count the number of breaths per minute to find the rate
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    Guys, during exercise do your blood vessels dilate or constrict? Your muscles will be working harder so you need more blood to them, but I'm a bit confused as to which one is the right one
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    (Original post by joan2468)
    Guys, during exercise do your blood vessels dilate or constrict? Your muscles will be working harder so you need more blood to them, but I'm a bit confused as to which one is the right one

    Blood vessels dilate because your body need to lose heat. More blood flow to the surface of the skin to increase the temperature so that water from sweat can be evaporated.
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    (Original post by joan2468)
    Guys, during exercise do your blood vessels dilate or constrict? Your muscles will be working harder so you need more blood to them, but I'm a bit confused as to which one is the right one

    (Original post by bubblegummer)
    Blood vessels dilate because your body need to lose heat. More blood flow to the surface of the skin to increase the temperature so that water from sweat can be evaporated.
    The dilate also to reduce blood pressure
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    (Original post by Lujain Al Omari)
    free radicals attach to proteins, lipids, and other structures in a cell, causing damage
    Thank you!

    How do these free radicals form? By cancer?
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    Could some please describe this in detail?
    1. Describe the techniques that would be used to insert the cancer causing genes into the cells of rats.
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    (Original post by joan2468)
    Guys, during exercise do your blood vessels dilate or constrict? Your muscles will be working harder so you need more blood to them, but I'm a bit confused as to which one is the right one
    I'm gonna exercise a bit for real so this might help. During the exercise my arterioles near the skin will dilate to lose heat because during exercise core body temperature increases. Adrenaline can cause vasodilation of arterioles going to my muscles for a good supply of blood flow so enough oxygen gets to it and removes carbon dioxide.
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    (Original post by EstebanK0)
    How much revision have you done?
    errmm...not a lot I only read the article properly yesterday

    (Original post by Sravya)
    I agree with you! What do you need in nuit5? have you got c4 in the morning on Tuesday?that's my last exam
    Yeah I have c4 on tuesday, i'm even more worried for that! I need an A

    (Original post by jojo1995)
    ahh bless i feel your pain i have chem too .... you'll be fine with maths and everything... it should go well considering they messed up c3 (i dont know why i have concluded that but lol). i tend to do better when i have less time to revise lol good luck .. you wont need it though
    ah i really do need it but thanks, good luck to you too! Yeah, c3 was a *****. If c4 is the same I don't know what I'm gonna do with my life ahah
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    (Original post by nukethemaly)
    Thank you!

    How do these free radicals form? By cancer?
    They don't form from cancer (well some might but this isn't the case with Oxygen radicals). They can be caused as a side product of metabolic processes, they can come from molecules being exposed to heat, radiation or generally anything that can break the bonds between molecules really. Sometimes the immune system will even produce them on purpose so they can be used to damage the cell walls and membrane of Pathogens!

    The building up of these radicals is what can be a factor in cancer development as they cause damage to DNA etc, which can lead to Mutation.
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    Do we need to know how anabolic steroids work?
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    (Original post by bubblegummer)
    Blood vessels dilate because your body need to lose heat. More blood flow to the surface of the skin to increase the temperature so that water from sweat can be evaporated.

    (Original post by Lujain Al Omari)
    The dilate also to reduce blood pressure

    (Original post by Sly1)
    I'm gonna exercise a bit for real so this might help. During the exercise my arterioles near the skin will dilate to lose heat because during exercise core body temperature increases. Adrenaline can cause vasodilation of arterioles going to my muscles for a good supply of blood flow so enough oxygen gets to it and removes carbon dioxide.
    Thanks for the answers guys, but I was wondering about the blood pressure during exercise - I thought if you need blood to flow faster to the muscles you need higher blood pressure? I'm thinking higher pressure = blood travels faster, but I'm not sure about this...
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    (Original post by Mjwilson1988)
    They don't form from cancer (well some might but this isn't the case with Oxygen radicals). They can be caused as a side product of metabolic processes, they can come from molecules being exposed to heat, radiation or generally anything that can break the bonds between molecules really. Sometimes the immune system will even produce them on purpose so they can be used to damage the cell walls and membrane of Pathogens!

    The building up of these radicals is what can be a factor in cancer development as they cause damage to DNA etc, which can lead to Mutation.
    Oh thank you!
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    (Original post by I Hate Edexcel)
    Do we need to know how anabolic steroids work?
    It's unlikely to come up but just learn everything to be safe, especially on this unit.
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    (Original post by nukethemaly)
    Could some please describe this in detail?
    1. Describe the techniques that would be used to insert the cancer causing genes into the cells of rats.
    Start by identifying the gene which is cancer causing (might be a Protoncogene etc).

    Isolate it and remove it using Restriction Enzymes (Restriction endonuclease is an example).

    Amplify it (copy it) using the Polymerase chain reaction, mention how you use DNA Polymerase to do this. Now you've got a load of copies, you need to insert it into a vector.

    Choose a Vector, such as a virus or a bacteria, I'll go for Bacteria, as I like the Plasmids. Using a Plasmid you need to open the ring of DNA (again, using Restriction Enzymes), and insert the gene into it, the enzyme used to fix a gene into a plasmid is call DNA Ligase. Now insert the plasmid into Bacteria (usually done by just mixing it with Bacteria and then killing off the ones who don't have the plasmid so you're just left with the ones who have the plasmid)

    Infect the rat with the bacteria/virus/whatever vector. The vector will carry the gene into the cells of the rat. The Cancer causing Gene will now be fused with the DNA of the rat and will be expressed, causing cancerous cell growth in the rat.
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    (Original post by nukethemaly)
    Could some please describe this in detail?
    1. Describe the techniques that would be used to insert the cancer causing genes into the cells of rats.
    1) microinjections: genes are injected into cells
    2) microprojectiles: genes are attached to gold and tungsten pellets and bombarded at high speed at the cells
    3) vectors: the whole unit 2 thing: restriction endonucleases, insert gene, DNA ligase...
    4) liposome wrapping: liposomes have phospholipid bilayer membrane, so contents enter cells when the 2 membranes fuse (endocytosis)
    6) electroporation: genes are introduced through temporary tiny holes in cell's plasma membrane that are induced by rapid brief electrical impulses introduced to cell membrane
 
 
 
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