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AS BIOLOGY:Why are the first signs of a heart attack referred pain down the left arm? Watch

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    Why are the first signs of a heart attack referred pain down the left arm?

    I am so confused, Is it because of angina?
    Or does it have nothing to do with that?

    Help, is what i need.
    :yep:
    Please!

    Does it have anything to do with the nerves?
    Or the medulla?
    Longshots I think :no:
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    I always thought nobody knew why this happens - referred pain.

    I wouldn't put that down as an answer though, haha.
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    Because your heart's on the left hand side, and when it stops pumping there's no oxygen being transported so the cells around there will produce lactate which is toxic and thus causes pain?

    I know that's why anaerobic respiration causes pain, but I'm only guessing that's why it's the arm. :p:

    Edit: Angina's just when the artery's narrowed, a heart attack is where it skips a beat. :p:
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    It's to do with the way the cutaneous nerves of the arm merge with the visceral nerves of the thorax at the dorsal horn. I should be able to give a better answer but I am tired

    And to respond to the person below heart attacks can also refer up the neck and to the jaw .
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    because your heart's on the left side of the body, i think.
    but it doesn't always need to be left arm pain; heart attacks can present with jaw pain, for example.
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    because your heart is in your arm, duh..
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    Its a bit complicated really... but if you want an AS answer I would say: Pain which originates from the heart is refered to the left wrist/arm because the neural pathways which carry information to the CNS from the two areas overlap to a certain degree.

    The sympathetic nerves which innervate the heart originate from the around the spinal level T1. They carry with them some afferent fibres which synapse at the same dorsal route ganglia as the somatic nerves from the same dermatomes ie. around T1 - this includes the arm. The brain usually recieves very little afferent information from the heart and thus, the pain is often perceived as originiating form the high-activity somatic pathway ie. the arm.
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    In my answer I ended up first reffering to angina and because of the narrowing of the arteries enough oxygen isn't getting to the cardiac muscles. Hence the pain "angina pectoris"

    But I also mentioned reffered pain and the overlaping of the left arm and heart nerves.


    Thank you !!:^_^:
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    (Original post by Gingersnaps)
    Why are the first signs of a heart attack referred pain down the left arm?

    I am so confused, Is it because of angina?
    Or does it have nothing to do with that?

    Help, is what i need.
    :yep:
    Please!

    Does it have anything to do with the nerves?
    Or the medulla?
    Longshots I think :no:
    This is likely to be entirely pointless seeing as this is a rather old thread, but here it goes:

    Cutaneous sensation areas can be mapped onto specific spinal nerves – these areas are called dermatomes. For example, sensation at your thumb is usually referred to the spinal nerve at level C6.

    The upper limb, however, embryologically, develops by protruding from the trunk. This means some dermatomes you would expect to be found in the thorax are not there – they have been 'pulled off' to form the upper limb. T1 is one of these dermatomes, corresponding to the medial side of the arm and part of the axilla.

    The heart is innervated by the cardiac plexus, which includes autonomic fibres leaving between the levels T1-T4. When myocardial tissue dies, sensory fibres transmit pain signals back to the spinal cord at these levels. The dermatomes corresponding to these levels are where one feels pain (I may be wrong, but I think visceral pain is usually not felt unless it is caused by extension / crushing), which explains chest (T2-T4) and arm (T1) pain. I can't explain why specifically the left arm, but I hope this was helpful anyway.
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    You get pain down the left arm because of the nerve innervation of the heart causing referred pain. Although, only 65-70% of people get this type of chest pain. Most patients who have a MI are elderly and have high risk factors. Those patients are least likely to present with pain down the left arm. Breathlessness, feeling of indigestion, sweating, general chest discomfort are more common. This group of patients often present to the hospital too late and end up with a poor prognosis. Therefore, it is more important to learn these "atypical symptoms" rather than chest pain. Only about 5-10% of the patients with MI present with jaw pain, which is very uncommon. More info about MIs can be found here: http://www.biologyguide.net/unit1/6b...ar_disease.htm

    Simon
 
 
 
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