The Respiratory System Life thrived on Earth primarily because of presence of Oxygen in the air. All animals and creatures living on earth have respiratory systems of various kinds, some may have lungs, others like fish may use gills, and yet others like some insects may breathe through pores in their bodies. Like other creatures and living organisms, man too needs oxygen to survive. When we breathe, air is taken in...

What is Sensation and Reflexes Coming out of the base of the brain is a cluster of nerves which spread all over the body forming the nervous system. The brain stern leads into the spinal cord which extends along the vertebrae upto the tail bone. From the central nerve stem peripheral nerves are extended to the other parts all across the body. These nerves carry messages back and forth from the...

Human Mouth and Teeth System Our mouth is an inlet in our body which allows us to eat, drink and breathe. The mouth has a hard palate at the top and the tongue at the bottom, surrounded by the teeth, and leading into the throat at the back. The tongue is a flexible muscle which serves the purpose of identifying taste, moving food around in the mouth while we are chewing...

The Nose and Smell The nose helps us in breathing and smelling things. The outer side of the nose is made of thick skin which is supported outwards with the help of a cartilage protruding outwards from the skull. The cartilage divides the nose from the centre thus giving us the two nostrils, at the rear these nostrils end up into a common cavity leading into the throat. Also leading into...

Eyes and Vision System As we read through this book, we saw a lot of written text, and pictures, we were able to see the images and rend the text with our eyes. The old saying ‘seeing is believing’ quite appropriately defines the importance and necessity of sight. Sight or vision is possible because of our eyes, which are located in two sockets in front of our skull. The eyeball measures...

Ears and Sound System Our ears not only allow us to hear sounds, thus preventing the world from becoming a silent one, but also act as organs of balance. They collect Alunds from the air and pass them to the brain in the form of nerve signals. Human beings can hear sounds within a certain wave length but animals like dolphins and bats can hear sounds of a much higher wavelength,...

The Brain and Nervous System The human brain is more complex than any computer known to man. In living creatures, mammals have bigger brains and man has the biggest in relation to his size. An average human brain would weigh about 1.5 kgs and would have a jelly like texture made up of billions of living units called nerve cells or neurons. It is housed in the topmost part of the...

Our Body and Its Systems Our body is a wonderful machine made of billions upon billions of tiny cells. Our body is capable of many feats which include coordination between its various parts and balancing in various situations. The cells in our body are so tiny that they can only be seen with the help of a microscope. Every second millions of cells in our body are dying and millions are...