Why are human bodies asymmetrical?

Symmetry is usually associated with beauty and is largely found in nature. The intricate patterns of a butterfly, a perfectly shaped leaf, the spots on a ladybug. Although we give a lot of importance to symmetry, on the other hand one should know that asymmetry is very important as well. We might notice symmetry easily but asymmetry is also pretty commonly found.

Human Body And Asymmetry

Although the exterior of the human body maybe pretty symmetrical, the inside of the human body has a different story to tell. Our internal organs are arranged in an asymmetrical manner – heart, stomach and spleen are on the left, the gallbladder and large part of out liver are on the right. Our lungs are also different from each other, the left one consists of two lobes and the right one has three. Even our brain with its similar looking two sides, but each side function differently. Although it all might seem pretty abstract, but the way in which the asymmetry is distributed in of vital importance.

Situs Inversus

If all the organs were to be flipped, although a harmless phenomenon, is known as Situs inversus. But if the reversal if is incomplete or half done, it can be rather dangerous and fatal. In cases where the heart is involved it can be rather complex and more dangerous.

How Dose Asymmetry Take Place ?

An embryo looks exactly the same on the left and the right, then how does asymmetry take place? The node on the embryo, which is small pit. The node is lined with tiny hairs called – cilia. These cilias tilt away from the head and whirl around pretty rapidly in the same direction. This movement causes the fluid from the right side of the embryo to move to the left. The left rim of the nodes, take note of this movement and sense this cilia flow. They in return activate specific genes on the embryo’s left side. These genes make for some proteins by directing the cells and this results in the chemical difference that are found on the right and left side of the embryo. Despite the sides looking different, the chemical differences make for the asymmetry found in the organs. This process of asymmetry takes place first in the – Heart. What begins as a straight tube from the center of the embryo becomes a c shaped bend rotating towards the right side of the body when the embryo turns three weeks old. Later on, it forms different structure on each side which makes for a symmetric heart that is found in human body. Similarly, other major organs also start their journey of growth from the central tube to further grow into their ultimate positions.

Chirality

The property that biomolecules have. Which means that a molecule and its mirror image are not identical. Asymmetry found at molecular level – makes for asymmetric cells which makes for – asymmetric embryos. And these asymmetric embryos are the reason for asymmetric organisms.

This proves that asymmetry is as important and intriguing as symmetry found in nature.

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