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bio DAT question

Discussion in 'Pre-Dental' started by ALI, Aug 2, 2002.

  1. ALI

    ALI Senior Member
    10+ Year Member

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    Hi everyone

    I have a question for everyone

    Cardiac muscle

    A. Is innervated by the somatic motor nervous system
    B. Is not striated
    c. is multi nucleated
    d. has voluntary contraction
    e. does not require Ca2+

    I don't know the anwer to this problem

    I think the answer is E or C. Because I know it is innervated by autonomic motor system, striated, has involuntary contraction. In kaplan book, it says it has one or two nucleus. Only one nucleus in some other books. I'm not sure if it require calcium or not. What do u think.

    Also what does myogenic mean. Why is cardiac and smooth muscle myogenic?
    Thanks in advance
     
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  3. bres

    bres Member
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    I have a question for everyone

    Cardiac muscle

    A. Is innervated by the somatic motor nervous system
    B. Is not striated
    c. is multi nucleated
    d. has voluntary contraction
    e. does not require Ca2+

    I don't know the anwer to this problem

    I think the answer is E or C. Because I know it is innervated by autonomic motor system, striated, has involuntary contraction. In kaplan book, it says it has one or two nucleus. Only one nucleus in some other books. I'm not sure if it require calcium or not. What do u think.

    Also what does myogenic mean. Why is cardiac and smooth muscle myogenic?
    Thanks in advance
    ___________________________________________________
    Yes, I saw that question somewhere in Kaplan.
    My opinion, this is not a good question..though.
    The book says cardiac muscle has 1-2 nuclei per cell, which we do not want to call it mutinucleated. As a matter of fact, even cardiac muscle is innervated with automonic nerves(which is involuntary), it can generate voluntary action in LAB condition.....?

    All muscles contain actin and myosin filaments even in smooth nuscle. But smooth muscles lack the organization of skeletal sarcomeres, this is why no striations in smooth muscles. Since all muscles have actin and myosin, Ca2+ is required in all muscle cells.

    myogenic activity = property of reflexively contracting without nervous stimulation, as being one of characteristics in cardiac and smooth muscles.
     
  4. DesiDentist

    DesiDentist G. S. Khurana, DMD, MBA
    Moderator Emeritus Exhibitor 10+ Year Member

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    I just looked over this question yesterday. Cardiac muscle is striated, and is not multinucleated (multi =3+ in my opinion) and it does requrire Ca++. The answer to this question according to kaplan was that it has voluntary contraction. I got this one wrong and I was like what the "heck" Because voluntary to me means a person can influence the heart's contraction. However, if you read the answer it means that if heart tissue was extracted and put into a ionic medium (with Na, Ca++, etc) the tissue would contract by itself. I think this is a worthless and very badly worded question.

    DesiDentist
     
  5. Beagle

    Beagle Meet BEAGLE
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    I got this one wrong too for the same reason as Desi.
    So does the heart contract volutnarily or not (assuming it is NOT in a petri dish)???
     
  6. DesiDentist

    DesiDentist G. S. Khurana, DMD, MBA
    Moderator Emeritus Exhibitor 10+ Year Member

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    Yeah, this questions is not good. Because in Kaplan they said only skeletal muscle contracts voluntarily. Cardiac and smooth muscle cannot be controlled voluntarily. So when I looked at this question the first answer choice i eliminated was "voluntary."

    DesiDentist
     

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