Slide #14

• If electrical stimulation of a muscle in a frog takes place over the 'A' band nothing happens.
• Contraction only occurs if stimulation occurs at the I-band (over the Z-line)

• This occurs because the T-tubule which transfers the electrical signal from the periphery of the muscle to the inside is located at the Z-line in Frogs.
• To invoke a similar contraction in Mammals the stimulus must be placed at the A/I junction.