Cardiovascular Physiology Exercise 6

Terms | Definitions | Explan why the larger waves seen on the oscilloscope represent ventricular contraction | the ventricle contraction is of greater force than the atrial contraction, this is due to the fact that ventricle's fxn is to send blood throughout the body. | Explain why the amplitude of the wave did not change when you increased the frequency of the stimulation in cardiac muscle. | amplitude does not change because the cardiacs long refractory period prevents summation. | Why is it only possible to induce an extrasystole during relaxation? | the extrasystole can not occur until relaxation and so we could not achieve wave summation tetanus | Explain why wave summation and tetanus are not possible in cardiac muscle tissue. | Cardiac cells have longer APs and twitches than any other muscle cells,therefore they do not show temporal summation | explain the effect that extreme vagal stimulation had on the heart. | the HR decreases and stopped the heart temporarily | Explain two ways that the heart can overcome excessive vagal stimulation. | 1: Sympathetic reflexes
2: initiation of a rhythm by the Purkinje Fibers | Describe how the sympathetic and parasympathetic nervous system work together to regulate heart rate | Sympathetic increases HR
Parasympathetic decreases HR | What do you think would happen to the HR if the vagus nerve was cut? | It would increase and go back to the 100bpm | Explain the effect that decreasing temperature had on the frog heart. | It slows the HR | Describe why Ringer's solution is required to maintain heart contractions. | it contains all the ions, pH, glucose, ATP need to keep the heart beating. | Explain the effect that increasing the temperature had on the frog heart. | it increase the HR | describe the effect that pilocarpine had on the heart and why it had this effect | -It decreases the HR
-it stimulates the parasympathetic nerves | Atropine is an acetylcholine antagonist. Does atropine inhibit or