This document discusses the effects of temperature, ions, drugs, and nerve stimulation on the frog heart as measured by cardiograms. It includes: 1) Drawings and explanations of ideal graphs showing how warm and cold saline affect the heart rate and amplitude of the sinus venosus and ventricle. 2) Descriptions of how the first and second Stannius ligatures prove the sinus venosus is the pacemaker and demonstrate auto rhythmicity. 3) A graph and definition of vagal escape along with its causes when stimulating the vagus nerve. 4) Graphs and explanations of how sodium, calcium, potassium, adrenaline, and acetylcholine affect heart rate and

1. Amphibian Graphs
Cardiac muscle
Dr. Sai Sailesh Kumar G
Associate Professor
Department of Physiology
RDGMC, Ujjain

2. Normal cardiogram
• Draw neat labelled ideal graph of normal
cardiogram
• Name pacemaker of the frog heart

4. Effect of temperature
• Draw neat labelled ideal graph of effect
of temperature on frog heart
• Explain effect of warm and cold saline
on the frog heart

7. Effect of warm saline on SV
• Warm saline
 Sinus venous is pacemaker of frog heart. So it
determines heart rate. When warm saline
applied, it speed up biological activities and
increases heart rate.
When heart rate increases, the end diastolic
volume decreases due to decrease in the
diastolic period. So force of contraction
decreases ( amplitude decreases)

8. Effect of cold saline on SV
• Cold saline
 Sinus venous is pacemaker of frog heart. So
it determines heart rate. When cold saline
applied, it slow down biological activities and
decreases heart rate.
When heart rate decreases, the end diastolic
volume increases. So force of contraction
increases ( amplitude decreases)

9. Effect of warm saline on Ventricle
• Ventricle is not the pacemaker. So there is no
change in heart rate.
• When warm saline is applied, due to increase in
the metabolism, there will be increase in the
amplitude.

10. Effect of cold saline on Ventricle
• Ventricle is not the pacemaker. So there is no
change in heart rate.
• When cold saline is applied, due to decrease in
the metabolism, there will be decrease in the
amplitude.

11. Effect of Stannius ligature
• Draw a neat labelled ideal graph of
effect of stannius ligature on frog’s
cardiogram.
• What are the properties proved by first
stannius ligature?
• What are the properties proved by
second stannius ligature?

13. Effect of Stannius ligature
• The primary pacemaker in the frog
heart is present in the sinus venosus.
(first stannius ligature)
• Auto rhythmicity (second stannius
ligature)

14. Effect of vagal stimulation
• Draw a neat labelled ideal graph on the
effect of stimulation of vagus nerve on
frog’s heart.
• Define vagal escape and give causes.

16. Effect of vagal stimulation
• Vagal escape
Even though vagal stimulation is continued, after
some time, the heart starts beating at a slower
rate. This is vagal escape.
• Causes
1. Exhaustion of stored acetyl choline in the nerve
2. Increases destruction of acetylcholine by heart
tissues
3. Liberation of adrenaline by simultaneous
stimulation of sympathetic fibers
4. Idio ventricular rhythm

17. Effect of ions on isolated frog heart
• Draw a neat labelled ideal graph of the effect
sodium/potassium/calcium on isolated frog’s
heart.
• Explain observed effects

19. Effect of ions on isolated frog heart
• Sodium- No change in heart rate. Amplitude of
contraction decreases.
• Calcium- Increases force of contraction. No effect on
heart rate.
• Excess of calcium- No effect on heart rate. Increase the
force of contraction with out allowing the relaxation to
complete. Finally heart stops in systole. This is called
calcium rigor.

20. Effect of ions on isolated frog heart
• Potassium- heart rate decreases and finally stops in
diastole.

21. Effect of drugs on isolated frog heart
• Draw a neat labelled ideal graph of the
effect of adrenaline/ acetylcholine on
frog heart
• Explain observed effects

23. Effect of drugs on isolated frog heart
• Adrenaline
• Increase in the heart rate and force of
contraction
• Acetylcholine
• Decrease in the heart rate and force of
contraction

24. THANK YOU