Skeletal and Nervous System
Nervous System
Our body has different system and all of the systems are control by our brain. Brain and nerves together makes nervous system.
Brain
Brain does all the important works. It remember our lessons, names of our friends, helps us to store information in our memory, it controls our body movement, etc. There are three parts in human brain.
These are Cerebrum, Cerebellum, and Medulla
Cerebrum
The forebrain is called cerebrum. Cerebrum is the largest part of the brain. It helps in learning, memory, intelligence, and logic.
Cerebellum
The middle part of our brain is called Cerebellum. Cerebellum is called mid brain also. Cerebellum is situated below the cerebrum. Cerebellum helps in muscle’s coordination and in maintaining the balance of our body.
Medulla
The lower part of brain is called Medulla. Medulla is called hind brain also. Medulla controls heart beat, breathing, swallowing, and sneezing, etc.
Spinal cord
Spinal cord is made up of bunch of nerve tissues. The spinal cord is long, thick nerves. Spinal cord transfers information from brain to other part of the body and from other parts of body to brain. Spinal cord controls all of the movements of our reflex action. Actions which we do unconsciously are called reflex action. Spinal cord passes from middle the back bone so that it is keep protected.
Nerves
The net like structures which passes messages in the form of signals to whole part of body is called nerves. Nerves are spread throughout in our body. There are two types of nerves in our body.
Sensory Nerves
Sensory nerves passes through the spinal cord and carry messages from body to the brain.
Motor nerves
Motor nerves carry messages back from the brain to the body.
Reflex action
The automatic response of the body to an event is called a reflex action. Reflex action is very fast. Our brain is not involved in any of the reflex actions. Reflex action is due to message sent by our external organ to the spinal cord. For example: when we touch hot glass of milk suddenly without knowing the degree of hotness, we remove our hand immediately without thinking about it. This happens because of reflex action. In other words this type of action is called reflex action.
Sense organs
Organs which enable us to sense the physical word are called sense organs. We have five types of sense organs. These are eye, ear, tongue, nose and skin. These sense organs help us to see, hear, taste, smell and touch. If there were no sense organs present to our body, we were never be able to understand the world.
Eyes
Eyes are the most important sense organ of animals. Eye enables us to see various things around us. Eye ball is placed in a bony socket in the skull. Eye balls are protected by eyelids and eye lashes. Eyelids and eye lashes protect our eyes from dust and dirt. The dark structure in the eyeball is called the iris. The small round black spot is called Pupil. The eye is connected to the brain by a nerve called optic nerve.
Eye is such an important sense organs that there is a very important catchy line written in the Eye Department of AIIMS, New Delhi, India
“Protect your eyes so that eyes protect you.”
Ears
Ears enable us to hear. Human ears are divided in to three parts – external ear, middle ear and inner ear.
External Ear
The external and visible part of ear is called External Ear. External ear is called PINNA also. External ear may vary in shape and size in different animals. External ear or pinna directs the sound waves to the middle ears. All mammals have external ears.
Middle Ear
The portion of the ear internal to the eardrum is called Middle Ear. Middle ear has an ear drum, and three small bones. Middle ear works similar to a drum which produces sound because of vibration.
Inner Ear
Inner ear found in the inner portion of the ear. Inner ear enable us to hear and maintain the balance our body.
You should know that Dolphins have the best sense of hearing among animals.
Tongue
Tongue enables us to get the taste of food items we eat. Different parts of the tongue have different taste buds. These taste buds are made to detect four special tastes like sweet, sour, salt, and bitter. Snakes have special type of tongue which they use to smell things.
Nose
Nose enables us to smell. There are nerves endings present in the nose which carry message about a smell that enters the nose and sends those signals to brain.
Skin
Skin enables us to feel things like heat, cold and pain. Skin forms a natural protective cover of entire body. There are many nerves ending present in the skin. These nerve endings help us to feel any things which we touch.