Chapter 10: Cardiovascular System
Erika J. Eliason, Andreas Ekström, Albin Gräns, Georgina K. Cox, and Erik Sandblom
The typical fish cardiovascular system comprises four major parts: a heart, blood vessels, blood, and control systems. Most water-breathing fishes have a closed, single-circuit circulatory system in which blood flows in a loop from the heart, through the gills, to the peripheral tissues, and back to the heart (Figure 10.1). Air-breathing fishes have more complicated circulatory systems (see Burggren et al. 1997). For a comprehensive review of the form, function, and control of the fish vasculature and heart, see Farrell and Smith (2017) and Sandblom and Gräns (2017).
The cardiovascular system transports oxygen, carbon dioxide, nutrients, wastes, immune factors, and hormones around the body. As such, it plays an essential role in supporting physiological processes such as digestion, locomotion, reproduction, osmoregulation and immune function (Farrell 2011; Gamperl and Shiels 2013).
This chapter outlines some of the most common techniques used to assess cardiovascular function in fishes. We specifically address the technical aspects of vascular cast use to assess blood vessel morphology, single and repeated blood sampling, major hematological techniques, and in vivo measurements of heart rate, blood pressure, and blood flow. We do not address any histological or microscopy techniques to evaluate morphology, cellular techniques to measure electrical excitability of the cardiomyocytes, or in vitro or isolated perfused heart techniques to measure cardiac function. For these methods, see Farrell and Smith (2017), Shiels (2017), and Vornanen (2017).