Question

Name an animal in which the heart pumps deoxygenated blood only.

Answer 1

Hint:- The heart is the vital organ that pumps blood to other organs throughout the circulatory system. Different animals have different types of hearts due to the difference in the number of chambers. Normally, humans and most mammals have 4 chambered hearts.

Complete step-by-step solution:- The heart performs the function of pumping oxygenated blood to different organs and receiving deoxygenated blood from the organ. The higher animals including humans have 4 chambered hearts.Fish have only two-chambered hearts i.e one auricle and one ventricle so there is no mechanism of separation of oxygenated blood and deoxygenated blood, therefore fish heart pumps deoxygenated blood. Fish have a single circuit for blood circulation due to one auricle and one ventricle.
In fish, deoxygenated blood from the body reaches the auricle and then ventricle which is then pumped towards the gill for oxygenation, and then it circulates throughout the body. So the fish heart pumps blood first to the gills where gas exchange takes place then towards the rest of the body. Fish’s gills are thin-walled so that proper gaseous exchange can take place and therefore cannot tolerate high blood pressure.
In humans, the heart has 4 chambers, 2 atriums, and 2 ventricles. The right atrium and the right ventricle receive deoxygenated blood which is pumped towards the lung for oxygenation and this oxygenated blood reaches the left side of the heart, which is then pumped throughout the body. This is called Double circulation and the heart is pumping both deoxygenated (towards lung) and oxygenated blood(towards the whole body). In amphibia, there are 3 chambers in the heart, so there occurs mixing and the heart pumps the mixture of oxygenated and deoxygenated blood.
So fish is an animal in which the heart pumps deoxygenated blood only.

Note:- Fish have a single circuit of circulation, so after oxygenation of blood in the gills, this blood does not come back to the heart, instead of from gills, blood directly moves towards other organs throughout the body.