BGYC34; First Assignment (2012)
PhysioEx Lab 6 (Cardiovascular Physiology)
Due Date: Friday, January 27, 2012
Perform the experiments in PhysioEx lab 6 (Cardiovascular Physiology). Provide the results requested, and answer the questions, for each of the following activities. There are a total of 25 marks.
Note: The activity names and numbers listed below correspond to those in PhysioEx version 9.0. If you are using an older version of PhysioEx the exact activity names and numbers may not match. In this case, identify which activities in the older versions correspond to the ones listed below and place the appropriate data in the corresponding section.
Activity 1: Investigating the Refractory Period of Cardiac Muscle
Results: Briefly describe what happened when you applied the electrical stimuli to the heart. (2 marks)
Question 1: Explain why the larger waves seen on the oscilloscope represent ventricular contraction. (1 mark)
Activity 2: Examining the Effect of Vagus Nerve Stimulation
Results: Briefly describe what happened when you electrically stimulated the vagus nerve. (2 marks)
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. (3 marks)
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. (2 marks)
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...