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dissection of the frog 3/20/2012 11:11:00 AM
Need this for lab report !
Proximal is the waist—where the stimulator is
The distal end is the knee joint –where te receptor is
This was used in the frog nerve experiment
Contents about lab 9
Between the ankle and the knee
Knee bone is on the upper clamp
The tendon ( ankle) is attached to the needle pen
All the weights are used in the part II
Increase the voltage until you see the first twitch
the needle pen draws the first bump on the revolving graph
you measure the amplitude of the peak /bump
o so first graph: Amplitude vs voltage
you keep incraseing the voltages until the ampliteu of the peak doesn’t
that’s your maximal voltage –level off on the curve
what is ‘spatial summation’?
in compound AP, in have one nerve, and many axons
o see higher and higher peaks of AP , as you recruit more and
same with muscle: many motor units for each muscle fibre
o as you increase V, you increase more and more of the units
o until all the muscle units are activated, and no more increase
in the amplitude of the peak/burp observed ( contraction of
the muscle ) –get your maximal voltage, associated with the
o so the amplitude of the peak means the contraction ability of
what is ‘temporal summation’?
need to make sure that all the motor units are firing—by keeping
at maximal voltage setting
depends on how oftern you force it to fire?
Use the frequency setting ( maximal voltage setting ) on the
stimulator , and increase frequencing setting knob
No weights added to the needle pen
1 amplitue Vs coltage graph –spatial summation
2 each cluster refers to one frequency ( 1Hz, 2Hz)
amplitude Vs frequency graph –tempotral summation
the above 2 nothing to do with weights
now you are adding weights to the needle pen
the weighing pen ( needle pen) starts with no weight—it’s the lever holding
the pen –so you don’t have stretched muscle when you are adding weights s
later ( in stretched muscle condition) you loosen the lever,
starts to see the dropping in the weighing pen—meaning the muscle is
getting stretched out
then add gradually more and more weights, and let the weighing pen to
draw peaks –now you have stretched muscle
notice that each time when you add more weights, you weighing
pen is dropping a bit more meaning the muscle is stretching more
what you see in non-stretched muscle condition?