Human Organs Lab Report

Investigating and comparing the relative masses of main fish organs to human organs.

Introduction

In biology an organ is defined as a collection of tissues structurally joined together in a unit to perform a specific function (Boyle). Humans and other animals have organs, for example; a brain. Due to evolution, all living things are very similar yet different from each other, for example all living things have cells but not all living things are able to speak. By taking a look at the internal organs of a fish, it can be found that certain systems and organs in fish are similar to those in humans; and also other systems and organs that are not. Fishes are aquatic cold-blooded aquatic vertebrates who have streamlined bodies that aid in swimming.

The heart of the fish comprised of 0.31% of the fish’s overall mass and the human heart contributed to 0.40% of its overall mass. These numbers show that the human heart is heavier than the fish’s heart and this could be due to evolutionary and physiological reasons. One of the reasons the fish heart was less heavy than hyman heart was that blood flows in the fish in a single circuit because fish heart is 2-chambered unlike regular 4-chambered heart found in mammals and birds. (Environmental Science Investigation) (See fig.4 )In fish, blood is pumped from the atrium of the fish into the heart’s ventricle and from the ventricle , the blood moved into the gills where gas exchange occurs in the gill filaments. CO2 is then expelled and O2 enters the bloodstream, from there the re-oxygenated blood flows into organs and tissues expelling CO2 from and replacing it with oxygen. The blood finally pumps back to the atrium where the process begins again. (University of Waikato) (See fig.5 ) In humans, blood enters the heart from the posterior and anterior veins vena cava which carries de-oxygenated blood from parts of the body into the right atrium. From the right atrium the blood flows into the right ventricle and through the tricuspid valve which shuts when the ventricle is full. The blood exits the heart through the pulmonic valve, into the pulmonary artery and then into the lungs where gas exchange occurs. Oxygenated blood is then carried by the pulmonary vein and into the left-atrium. The blood into the left ventricle through the mitral valve. The blood exits the heart through the aortic valve, into the aorta and the rest of the body. The complexity of the human circulatory system and the simplicity of the fish’s serves as a reason for why the human heart is