I don't expect all of it to be answered but questions 2-5 are giving me some trouble. If you want to chime in with the results, just to see if I'm in line with what others got, that would be nice as well. Any help would be greatly appreciated though. Thanks.
Activity 2: Examining the Effect of Vagus Nerve Stimulation
Results: Briefly describe what happened when you electrically stimulated the vagus nerve. Question 2: Explain how possible mechanisms of vagal escape would differ in an isolated heart preparation such as the one used in this experiment versus a heart in a live animal/human.
Activity 3: Examining the Effect of Temperature on Heart Rate
Results: Provide the heart rate values recorded when the heart was bathed with Ringer’s solution of different temperatures.
Question 3: Homeothermic animals such as humans have a thermoneutral zone (i.e., a range of external environmental temperatures) in which internal body temperature remains at a constant level while simultaneously maintaining metabolic rate (i.e., energy expenditure) constant. If the environmental temperature drops below the thermoneutral zone, humans can still keep internal body temperature constant (as long as it isn’t too cold). However, in this case, metabolic rate does not simultaneously remain constant but, rather, it increases.
a) In this case (below the thermoneutral zone), what would happen to heart rate (in an intact living human)? Explain your answer.
b) If an isolated human heart were used in an experiment such as the one in this lab exercise, what would be the effect of bathing the heart with cold Ringer’s solution (compared to regular temperature Ringer’s)? Explain your answer.
Activity 4: Examining the Effects of Chemical Modifiers on Heart Rate
Results: Provide the heart rate values recorded when the heart was bathed with normal Ringer’s solution, epinephrine, pilocarpine, atropine and digitalis. Question 4: a) What would be the effect on heart rate of bathing an isolated human heart (in a preparation such as the one used here) with nicotine? b) What would be the effect, on heart rate, of injecting nicotine into the blood in a live human? Explain your answers.
Activity 5: Examining the Effects of Various Ions on Heart Rate
Results: Provide the heart rate values recorded when the heart was bathed with normal Ringer’s solution, calcium, sodium and potassium. Question 5: The calcium channel blocker, verapamil is used to treat angina (a form of chest pain) that is associated with coronary artery disease. What is the mechanism of action by which verapamil treats and prevents the occurrence of angina?
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