Normal Cardiogram

Overview

This application is an educational simulation of a classic physiological experiment: recording a frog's cardiogram on a smoked drum kymograph using a Starling heart lever. It visually demonstrates the rhythmic, continuous contractions of the frog heart and the localized physiological effects of temperature on heart rate (chronotropy) and contractility (inotropy).

Key Physiological Principles

• The Cardiac Cycle: Unlike isolated skeletal muscle twitches, the frog heart acts as a functional syncytium. The simulation accurately models the overlapping contractions of the Sinus Venosus (SV), Auricles (A), and Ventricle (V) into a single, continuous, multi-peaked complex.
• Temperature on Sinus Venosus (Chronotropic Effects): The sinus venosus acts as the pacemaker of the frog heart.
  • Cold on Sinus: Induces bradycardia (slower heart rate). Due to the intrinsic Frank-Starling mechanism, the increased diastolic filling time stretches the ventricular muscle fibers more, resulting in a significantly stronger secondary ventricular contraction.
  • Warm on Sinus: Induces tachycardia (faster heart rate). Decreased filling time leads to a weaker ventricular contraction.
• Temperature on Ventricle (Inotropic Effects): * Cold on Ventricle: Directly decreases the force of ventricular contraction (negative inotropy) without altering the pacemaker's heart rate.
  • Warm on Ventricle: Directly increases the force of ventricular contraction (positive inotropy) without altering the heart rate.

How to Use the Application

1. Normal Cardiogram Tab:
   • Click "Start Recording (Room Temp)" to see the baseline cardiac cycle.
   • Observe the markers for SV, A, and V and notice how the upstrokes and relaxations merge seamlessly.
2. Effect of Temperature Tab:
   • Use the "Normal (25°C)" button to establish a baseline white trace.
   • Apply localized temperature effects using the respective buttons: "Cold on Sinus", "Warm on Sinus", "Cold on Ventricle", and "Warm on Ventricle".
   • Compare the overlapping, color-coded traces to visually distinguish changes in cycle length (horizontal stretch/compression) and amplitude (vertical height).
   • Use "Clear Drum" to reset the kymograph canvas.