Related Experiment Video
Updated: Sep 20, 2026

High-Frequency Ultrasound Echocardiography to Assess Zebrafish Cardiac Function
Published on: March 12, 2020
Form and function of the bulbus arteriosus in yellowfin tuna (Thunnus albacares): dynamic properties
Marvin H Braun1, Richard W Brill, John M Gosline
1Department of Zoology, Cambridge University, Downing Street, Cambridge, UK, CB2 3EJ. mhb31@cam.ac.uk
Abstract:
The bulbus arteriosus of the teleost heart possesses a static inflation curve that is r-shaped over the in vivo pressure range. To examine the possible significance of this in living animals, we recorded arterial blood pressure from anaesthetized yellowfin tuna and utilized a video dimensional analyser to simultaneously record changes in bulbar diameter. By plotting the changes in pressure against the changes in diameter, it was possible to create dynamic pressure-diameter (P-D) loops as well as calculate the instantaneous volume changes within the bulbus. The dynamic P-D loops showed the same features exhibited by static inflation. When nearly empty, a small stroke volume caused a large increase in blood pressure, while around systolic pressure large changes in volume resulted in small changes in pressure. We conclude that these features allow the bulbus to maintain ventral aortic flows and pressures over a large range of volumes.
Related Concept Videos
Structure of Blood Vessels
Heart Valves
The AV valves prevent the backflow of blood from the ventricles to the atria during ventricular contraction. These valves function with the assistance of the chordae tendineae and papillary muscles. When the ventricles are relaxed, the chordae tendineae are slack, allowing blood to flow from the atria into the...
Chambers of the Heart
Deoxygenated blood from the body is received in the right...
Fascicle Arrangement in Skeletal Muscles
The four primary types of muscle based on fascicle arrangement are:
Anatomy of the Circulatory System
Arteries and Arterioles

