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While it definitely slowed, the contractions were sporadic at best. The heart lost its regularity and showed random contraction intervals, some ranging shorter than normal while others had greater time gaps between contractions.
Procedure 5: Effects of a Ligature on the Heart
After the knot had been tied around the AV groove, no noticeable alterations were noticed to heart contraction. Upon tightening of the thread however, the heart appeared in clear distress. Beat irregularities ensued with an increase in magnitude of each pulse. The heart ceased functioning before the allotted time period had elapsed.
Discussion
Procedure 1: The Heart Rate
The resting heart rate of the frog was perfectly normal. Steady, rhythmic contractions around 60 beats per minute were observed and used as a baseline for other experiments. The frog appeared healthy, showing no signs of beat irregularities or any other defects that may have impacted the experiment’s …show more content…
The heart contains many adrenergic receptors which are responsive to epinephrine, especially near the SA node, which initiates the contractions of the heart. Epinephrine acts to increase the release time of calcium from the sarcoplasmic reticulum via a cascade of reactions. The fact that epinephrine had a positive impact on the heart indicates that the heart was healthy and responsive to normal physiological chemicals and pathways.
Addition of acetylcholine predictably lowered the heart rate of the frog. Acetylcholine blocks the cAMP cascade pathway that ultimately leads to calcium release, thus the frequency at which calcium is released is lowered and as a result, the contraction rate follows suit and lowers as well which is what you would expect from a fully functional heart. This part of the experiment was a …show more content…
It is produces electrical currents that travel to the AV node and through the Bundles of His and the Purkinje fibers and stimulates the cells of the atrium and ventricles to contract. This is electrical conduction that is carried through gap junction of the intercalated disks separating heart cells and thus it is reasonable to infer that applying an electric current directly to the heart would interfere with the steady, rhythmic contractions normally observed in a healthy, undisturbed heart. Accordingly, as we applied a current to the heart, the cyclic contractions of the heart became erratic and unpredictable. No steady pattern was detectable in the muscular contractions. Some had longer periods between contractions while others had shorter time gaps between beats. This was expected as the heart would be receiving constant signals to contract along with the rhythmic electrical signals from the SA node itself and would result in interference and overlap of contraction signals which is exactly what was observed. This leads us to believe that both the electrical apparatus and the heart were working exactly as
Procedure 5: Effects of a Ligature on the Heart
After the knot had been tied around the AV groove, no noticeable alterations were noticed to heart contraction. Upon tightening of the thread however, the heart appeared in clear distress. Beat irregularities ensued with an increase in magnitude of each pulse. The heart ceased functioning before the allotted time period had elapsed.
Discussion
Procedure 1: The Heart Rate
The resting heart rate of the frog was perfectly normal. Steady, rhythmic contractions around 60 beats per minute were observed and used as a baseline for other experiments. The frog appeared healthy, showing no signs of beat irregularities or any other defects that may have impacted the experiment’s …show more content…
The heart contains many adrenergic receptors which are responsive to epinephrine, especially near the SA node, which initiates the contractions of the heart. Epinephrine acts to increase the release time of calcium from the sarcoplasmic reticulum via a cascade of reactions. The fact that epinephrine had a positive impact on the heart indicates that the heart was healthy and responsive to normal physiological chemicals and pathways.
Addition of acetylcholine predictably lowered the heart rate of the frog. Acetylcholine blocks the cAMP cascade pathway that ultimately leads to calcium release, thus the frequency at which calcium is released is lowered and as a result, the contraction rate follows suit and lowers as well which is what you would expect from a fully functional heart. This part of the experiment was a …show more content…
It is produces electrical currents that travel to the AV node and through the Bundles of His and the Purkinje fibers and stimulates the cells of the atrium and ventricles to contract. This is electrical conduction that is carried through gap junction of the intercalated disks separating heart cells and thus it is reasonable to infer that applying an electric current directly to the heart would interfere with the steady, rhythmic contractions normally observed in a healthy, undisturbed heart. Accordingly, as we applied a current to the heart, the cyclic contractions of the heart became erratic and unpredictable. No steady pattern was detectable in the muscular contractions. Some had longer periods between contractions while others had shorter time gaps between beats. This was expected as the heart would be receiving constant signals to contract along with the rhythmic electrical signals from the SA node itself and would result in interference and overlap of contraction signals which is exactly what was observed. This leads us to believe that both the electrical apparatus and the heart were working exactly as