VPB 121: Veterinary Physiology - II (2+1)

EFFECT OF TWO SUCCESSIVE STIMULI - PROCEDURE

• Arrange the apparatus and the muscle nerve preparation as for recording a simple muscle curve.
• Adjust the point of attachment of the muscle to the lever so as to give a curve of about 3” height.
• Separate the two contract arms sufficiently apart and record two separate simple muscle curves in one revolution of the drum on the lower third of the drum.
• Mark the point of stimulation, point of initiation of contraction, point of maximum contraction and point of complete relaxation. Compare the second curve with the first.
• Using the first curve and lever point as reference bring the second contact arm near the first so that the second stimulus falls within the period of relaxation of the first muscle contraction.
• Lower the drum and record the contractions on the middle third of the drum.
• Mark the point of stimulation, point of initiation of contraction, point of maximum contraction and point of complete relaxation and compare this curve with the first.
• Similarly, adjust the second stimulus to fall with in the period of contraction of the first contraction. Record the contractions on the upper third of the drum.
• Mark the point of stimulation, point of initiation of contraction, point of maximum contraction and point of complete relaxation and compare it with the first.