Why Do Humans Have Four Chambered Heart?
A question often comes up when amphibians and reptiles like frogs and lizards are doing fine with their three-chambered hearts; why do we humans need a four-chambered heart for survival?
The content will discuss this topic in detail, focusing on several other significant aspects as well.
A Brief Overview
Humans, including all mammals, are endothermic and warm-blooded. Warmblood needs an extensive account of oxygen to produce ATP (Adenosine Triphosphate) and heat.
A four-chambered heart is way more advantageous than a three-chambered heart.
You need to know more about the chambers and circuits for getting complete knowledge of the characteristics and functionalities of the four-chambered heart.
A three-chambered heart has two ventricles and one atrium.
The atrium receives the blood from the body, and the ventricle helps pump the blood out to different parts of the body.
Two atria segregate two circuits – the pulmonary and systemic circuits.
Here, you have to think of the heart as the left heart and the right heart.
The right atrium takes in deoxygenated blood (low oxygen & high carbon dioxide) from the systemic circuit.
The oxygenated blood is sent to the left atrium (high oxygen & low carbon dioxide) from the pulmonary circuit.
In a three-chambered heart, both the atria pump the blood to one ventricle, and then pumped out blood is a mixture of oxygenated and deoxygenated blood.
The four-chambered heart is an evolution of the separate systematic and pulmonary circuits.
The addition of one ventricle has increased the amount of oxygen in the tissues.
The right atrium of the human heart delivers the deoxygenated blood from the body parts to the right ventricle that pumps the blood to the pulmonary circuit (lungs).
Similarly, the left atrium pumps the blood from the lungs to the left ventricle that pumps the blood to the systemic circuit (body).
Vessels and Chambers
The oxygenated blood of the arteries of the systemic circuits leaves the left ventricle of the heart.
After leaving the heart, all the blood vessels pass through the top of the heart.
There the aorta arches flow downwards to pump the blood to the lower body parts.
Three large branches are there at the top of the arch upwards.
This way, the systemic circuit is segmented into two parts.
When the right atrium contracts itself, the blood passes through the atrium and ventricle.
The valve is known as the AV valve or tricuspid valve.
When the blood is pumped out from the right ventricle, the right AV valve stops the backflow into the right atrium.
The movement of the right ventricle walls pumps the blood through another valve named the pulmonary semilunar valve.
Here, the blood is pumped into the left and right pulmonary artery before reaching the lungs.
The blood leaves the heart through a single vessel and pumps out in opposite directions.
On the other side, it comes out from different vessels to the heart when the blood returns.
The triangular cone shape of the apex indicates the contraction of the heart.
The contraction of the ventricles narrows and shortens the size and keeps the blood flow equal to both of the lungs.
The clean and pure blood returns from the lungs via pulmonary veins.
The Advantages of Four-chambered Heart
A four-chambered heart has more significant advantages over simpler structures.
A four-chambered heart enables humans to pump in the deoxygenated blood to the lungs and pump out the clean blood to the rest of the body.
In this entire process, two blood types never get mixed.
The process is very subtle and efficient. The blood pumped out from the left heart is pure and is of high oxygen level.
This oxygenated blood supplies energy to the muscles.
A fish heart pumps half-pure blood because it does not comprise separate chambers to clean the blood separately and distribute it throughout the body.
This is why the human body is fuelled with energy.
We can do other work between our meal times, but fish has to gather all the energy from food. Fishes live by eating all the time.
The energy requirement of human beings is so massive that the human heart needs the segregation of clean and polluted blood to pump out the filtered blood throughout the body.
Lungs, pulmonary arteries, and arteries serve as the medium of oxygenation, and veins and arteries work for blood circulation.
This process is has been termed Double circulation.
The Benefits of Four-Chambered Heart
a. Maintains blood pressure
b. Pumps the blood to the lungs frequently, and, the blood becomes pure and clean with oxygen
c. Helps to separate the oxygenated and deoxygenated blood
d. Reduces the threat of heart attacks and cardiac problems
e. Boosts the brainpower with clean blood flow
As we have already discussed earlier, humans need massive energy and require a huge amount of oxygen. Only the four-chambered heart can make this process possible.
Evolution
The four-chambered human heart is nothing but a result of evolution.
The size and shape of the heart have evolved through generations and species.
Scientists have provided us with a better view of how the structure of the heart evolved.
In the beginning, comes the tube-like heart, which is similar to a fish heart.
When the tube heart is divided into two chambers, it resembles the frog heart, then one extra chamber was added to the system, and the heart became three-chambered like that of a turtle or snake.
Finally, the heart becomes a four-chambered one – the heart of humans. Humans are the most evolved mammal to date.
Problems & Issues
At times, children accidentally are born with congenital heart diseases. Predominantly, the children suffer from ventricular septum defects.
In that case, that particular human child is deprived of its innate ability.
However, solutions and treatments to these diseases have been invented by researchers and doctors.
To conclude, the content has focused on the need of humans for the four-chambered heart structure.
The major significances of a heart with four chambers are that it provides the body with energy, and secondly, with heat.
I Hope, the content will guide you.
