Lab 12: Cardiac Function

Frog pinned to dissection tray, chest open with heart exposed.

Chapter 16

Using the same equipment set-up from the previous week, this lab's focus is on the anatomy and physiology of the heart. Again using a frog, students carefully hook up the apex of the frog's heart to the force transducer to obtain a recording of the frog's normal heartbeat. One of the objectives of this lab is to identify differences between skeletal muscle students saw last week and cardiac muscle. To observe these differences, students observe the refractory period, effect of stretch on contraction strength and attempt to obtain tetanus.

Amplifier and force transducer hooked to suspended muscle sample.

Students also note what can happen when the electrical activity of the heart is altered, as in heart block.

Bottles of epinephrine, nicotine and acetylcholine next to a syringe.

Finally, students examine the effects of three drugs on the heart's contractions: epinephrine, nicotine and acetylcholine.