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THERMAL INCREMENTS FOR PULSATION-FREQUENCY IN "ACCESSORY HEARTS" OF NOTONECTA.

W J Crozier¹, T J Stier

¹Laboratory of General Physiology, Harvard University, Cambridge.

The Journal of General Physiology

|October 30, 2009

Summary

This summary is machine-generated.

Pulsation frequencies in Notonecta swimming-leg "accessory hearts" were analyzed concerning temperature. Findings support specific thermal increment interpretations in isolated biological systems.

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Area of Science:

Zoology
Insect Physiology
Thermodynamics

Background:

Accessory hearts in Notonecta (water boatmen) are isolated systems.
Studying these organs may reveal insights into critical thermal increments.
Central nervous control is absent in these accessory hearts.

Purpose of the Study:

To investigate the relationship between temperature and pulsation frequencies in Notonecta accessory hearts.
To find evidence supporting the significance of critical thermal increments in isolated biological systems.

Main Methods:

Isolated swimming-legs of Notonecta were used.
Pulsation frequencies were measured.
Frequencies were analyzed in relation to varying temperatures.

Main Results:

Observed micro values for pulsation frequencies included 8,200, 16,200, 32,200, 11,400, 19,800, and 24,500.
These values differed significantly from typical arthropod heart beat frequencies (e.g., 12,300).
Irreversible changes in pulsation frequency occurred, sometimes with altered thermal increments.

Conclusions:

The observed thermal relations in Notonecta accessory hearts confirm previous interpretations.
The study provides further evidence for the role of critical thermal increments in isolated physiological systems.