Related Experiment Video
Updated: Dec 1, 2025

Deep Vascular Imaging in the Eye with Flow-Enhanced Ultrasound
Published on: October 4, 2021
Physiology and evolution of oxygen secreting mechanism in the fisheye
1Aarhus Institute of Advanced Studies, Aarhus University, Aarhus C, Denmark; Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus C, Denmark.
Abstract:
Most teleost fishes possess a unique system for tissue oxygen supply, where oxygen is delivered to the retina at partial pressures that exceed one atmosphere, providing a steep gradient for oxygen diffusion through their thick avascular retinas. This exceptional physiological system works through the elaborate interplay between highly pH-sensitive hemoglobins, acid-producing metabolic pathways, and a retinal vasculature with specialized structural and functional properties. This graphical review summarizes recent advances in understanding the mechanisms underlying retinal oxygen secretion and their impact on visual processing. Further, it discusses how the evolution of this complex physiological system provided the essential physiological exaptations for the adaptive improvements of vision in early teleost evolution. Finally, it summarizes knowledge gaps and directions for future research on this unique system for tissue oxygen supply.
Related Concept Videos
Anoxygenic Photosynthesis
Osmoregulation in Fishes
Oxygenic Photosynthesis
Mechanism of Breathing III: The Accessory Muscles
The respiratory system is a complex network that relies on primary respiratory muscles like the diaphragm, but also involves accessory muscles to enhance lung expansion and airflow during both inhalation and exhalation.
Enhancing Inhalation with Accessory Muscles:
Accessory muscles such as the sternocleidomastoid, scalene, intercostal, and abdominal muscles are crucial when additional respiratory effort is required, such as during deep...
Physiological Control of Respiration
Breathing, a seemingly passive process, is regulated by the respiratory center in the brainstem. This center coordinates the involuntary control of respirations, which means it occurs without conscious effort, ensuring a smooth and uninterrupted pattern.
Regulation of Ventilation
The body maintains ventilation by monitoring levels of carbon dioxide (CO2), oxygen (O2), and hydrogen ion concentration (pH) in the arterial blood. Among these factors, the level of CO2 plays a crucial...
Gas Exchange and Transport

