The Human Body

The human body is the most well defined of all animals. We are the most intelligent as well!
Like any vertebrates, the parent family to which the humans and other mammals belong, humans have
an internal bone structure.  This is called the skeleton. It includes a backbone of vertebrae. Above the skeleton lie layers of tissues, flesh, networks of nerves and blood vessels as well as fats. All these layers are topped by the layers of skins. 

And, like any other mammal, the sub family or the vertebrates, the human body shows certain common things such as hair, mammary glands, and highly developed sense organs. Despite these similarities, 

there lie many differences. The differences that has made human so unique. In no other animal you will find so much of perfection. The right thing at the right place and of right size. There lies two to three of the cages that hurries any activity.

Take, for instance, the backbone, the rod like bone joint, is common to all vertebrates.  But human backbone has a unique feature. Because it helps human to be blessed with a stable two-legged erect posture. Thus human can walk straight for hours only on two limbs. The vertebrates,  have all got a spine-like bone joints. Even those who hop on two legs when moving rapidly, like the marsupial kangaroos, walk on four legs and uses their tails as a "third leg" to stand. So is the case with the primates like the half-erect chimps and guerrillas who use all fours more often than two limbs.  

Moreover, the human brain is by and large the most highly developed in the animal kingdom. As intelligent as are many other mammals--such as chimpanzees and dolphins--none have achieved the intellectual status of the human beings.

Let us take down a look at ourselves. It is a unique combination of two(s). Our body has two sides. The front side called the ventral side. And the dorsal or the back side. Height wise too, it has got two different ends. The anterior, or the head, end. And a posterior, or tail, end. So is the case with the most other body parts. Like two pairs of limbs, two halves of breast, each housing a similar looking cage-like bony structure, called ribs. At the top of the ribs sit two shoulders. Above this the tube like neck is crowned by the head. Even the head has got a set of two eyes, two ears, two sets of teeth, two nostrils. And they are distributed in such a manner that if the whole body is sliced cutting from the head to the tailbone, two similar looking halves will come out. This is why human body is called predominantly symmetrical.    

Let us start with the limbs. Like any other mammals humans have two pairs of limbs. But for none other, the upper and lower limbs have such distinctive jobs to do. The slimmer and lighter upper limbs are hands. Made of upper and lower arms, the knuckle and the fingers. The elbow hinges the upper arm to the lower one. The wrist hinges the lower arm to the padded palm, the knuckles and fingers. Obviously all are meant for doing all the handy jobs - mighty and also the finer ones. 

The heavier lower limbs are the legs. Each one is made of thigh, calf, and feet. The thigh is hinged at the hip joint. The sheen and the calf are hinged at the knee, while the feet and the hill are hinged at the ankle. All are meant for doing the leggy business. They do not only help you stand, and walk, and run, and sit, and lie down and jump like other animals. But they also help us hold our 'default' erect posture all the time.

The legs are hinged at the pelvis with the  upper body, or, the trunk, through the hip joint. Hip has a pair of bones connected at the tail bone inside. At the outside the hips are also divided into two halves. Each has got an extra pad of flesh at the hind to help you do things, like sitting, and  lying down. Ii is the hip joint that supports and balances the trunk.
The hips apart, the pelvis contains and supports the The excretory organs, like the urinary bladder and tubes, the ends of intestines. Each of them helps us get rid of the body wastes. The pelvis also contains internal reproductive organs. These organs are different for different sexes.

Moving up higher, lies the abdomen. It is the largest cavity or hollow space in the human body. It has got no bone support except the rod like backbone that runs through the hind side. It houses many important organs. The digestive organs, including the pancreas, liver, intestines, spleen, gall bladder lie here. These organs produce juice like secretions which help the process of digestion. The abdomen also contains the base of the excretory organs, like the kidneys. 

Moving up still further, there lies the chest. It is the second largest cavity.
Human chest is supported by a cage-like bone structure made of 12 pairs of ribs, the breastbone. And the backbone part at the hind side. Chest contains the chief organs of respiration and circulation. They include the lungs  some air passages, the heart. The lung is placed within the right rib cage. And the four-chamber human heart is in the left cage. In between the two rib cages runs the food pipe, called the esophagus. Below, the chest is bounded by an elastic screen, called diaphragm. This screen separates the chest cavity from the abdominal one. 

The chest is connected at the shoulder to the head through the neck. At the front side is the throat, made up of  the cone shaped pharynx. The pharynx connects the mouth and the nose endings at the head to the wind pipe and the food pipe. The food pipe is called the esophagus. And the larynx includes the mouth of the wind pipe and the voice box. The wind pipe, or the trachea, a 10 to 12 cm long tube, carries air down to the lungs. The  food pipe, or esophagus, originating from the throat opening runs through this supple tube-like part, down to the chest and tummy. The pharynx chamber, thus, serves both the breathing and digestive functions.  

Top of all lies the head. It is like the cockpit of a plane that drives the functioning of the whole body. It houses the eyes, and ears, the nose and the mouth. And it has brain, protected inside the hard shelled skull. All these help us see, smell, hear, and taste.  And most importantly, think.
All major nerve endings that receive and send signals from outside and also from within the body lead to the brain. 

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