My human body book
The Nervous System
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The main function of the Nervous System is to interact with the environment.
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The nervous system is made up of neurons. There are millions of neurons in our brain. Neurons receive and transmit messages from different parts of the body to and from the brain.
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In order to fulfil the basic life process of interaction, the nervous system works with the Locomotor System. When the brain receives information, it sends a message to the part of the body to tell it how to react (or move).
PARTS OF THE NERVOUS SYSTEM: The major organs that belong to the nervous systems are:
The brain receives information, it sends a message to a part of the body to tell it how to react. The cerebrum is the largest and most complex part of the brain. It controls our intelligence, memory, personality, emotion, speech and the ability to feel and move.
The cerebelum is responsible for balance, movement and coordination. The brainstem coordinates all the messages going in and out of the brain to and from the spinal cord. It also controls involuntary movements, such as breathing, digestion, or our heartbeat.
The spinal cord connects the brain to the rest of the body. This cord is made up of nerve tissue, forming a long, thick tube.
The nerves connect the spinal cord to the muscles, joints and skin.
NEURONS: The neurons are star-shape cells that consist of a cell body along extension called the axon, and shorter, thin fibres called dentrites. To transmit messages they create electrical signals called nerve impulses. These impulses pass messages from one cell to the next.
At the end of the neuron is the cell body. It controls the neuron and creates nerve impulses.
The axon transmits this nerve impulses to other neurons.
Dentrites receive nerve impulses from other neurons.
THE SENSES:
You have five senses – sight, smell, sound, taste and touch. Each one of them is really important in your everyday life. You use at least one of your five senses every moment of every day and they are on duty even when you are asleep! Your senses work together to let your brain know what is going on around you. They help to keep you safe by warning you of any danger.
SKIN and TOUCH:
Our sense of touch enables us to touch and feel things with our skin our dermis.
How does our sense of touch work? Nerve endings detect information about the objects that we touch. They produce nerve impulses which the sensory nerves transmit to the brain.
EYES and SIGHT:
Our eyes are like cameras - they take images from the world around us and send messages to our brain.
How do we see? The light goes into the eye through the pupil. They it passes through the lens. The lens projects and upside down image onto the retina and this information is sent to the optic nerve. Then the optic nerve transmits the information to the brain. Our brain interprets the information, and figures out what we are looking at.
EARS and HEARING:
The sounds we hear every day are collected by our ears. Hearing helps us to learn and to communicate with everyone around. Our ears also have another really important job – they stop us from falling over!
There are three main parts: the outer ear (ear and ear canal), the middle ear (eardrum and hammer) and the inner ear (stirrup, cochlea and auditory nerve).
How do we hear? The sound waves go into our ear and hit the eardrum, as a result, the eardrum vibrates. When the eardrum vibrates, it makes the small bones inside the ear vibrate too. The cochlea detects the vibrations and produces nerve impulses. The auditory nerve transmits these impulses to the brain and the brain interprets the information.
ďƒź MOUTH and TASTE:
We use our tongue to taste. We can detect thousands of different tastes with our tongue. How do we taste? The tiny, pink bumps on our tongue are called tastebuds. They can detect special chemicals in the things that you eat and drink. The chemicals mix with saliva and then the tastebuds detect them. The tastebuds produce nerve impulses and transmit them to the gustatory nerves. These nerves are inside the tongue, connected to the tastebuds. These nerves then transmit the impulses to the brain. Finally, the brain interprets the information.
ďƒź NOSE and SMELL:
Our nose does a lot more than keep your glasses in place! It allows us to smell and to taste the food you eat. The nose is the beginning of our
respiratory system. It also contains tiny hairs that help to keep you healthy by trapping dust and microbes.
How do we smell? Smells are made up of gases in the air. When air goes into our nose, the gases go into our nasal passages. The olfactory cells detect the gases and send nerve impulses to the olfactory nerve, which transmits the impulses to the brain, and the brain finally interprets the information.
The senses of smell and taste work together. Our tastebuds detect different tastes, such as sweet, salty, sour and bitter tastes. Our olfactory cells detect thousands of different smells.
ILLNESSES: Some of the illnesses related to the nervous system are: Alzheimer, amnesia, lymes diseases, disabilities, ALS,…
INTERESTING FACTS ABOUT THE NERVOUS SYSTEM: - There are more nerve cells in the human brain than there are stars in the Milky Way. - If we lined up all the neurons in our body it would be around 600 miles long. - There are 100 billion neurons in your brain alone. - A newborn baby's brain grows almost 3 times during the course of its first year. - The left side of human brain controls the right side of the body and the right side of the brain controls the left side of the body. - A New born baby loses about half of their nerve cells before they are born. - As we get older, the brain loses almost one gram per year. - There are about 13, 500,000 neurons in the human spinal cord.
- The total surface area of the human brain is about 25, 000 square cm.
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QUESTIONS ABOUT THE NERVOUS SYSTEM:
1. What are the three basic life processes? What basic life process performs the
nervous system? 2. What is the nervous system? How does it work? 3. What is the nervous system made up of? 4. What are the five senses? 5. How do neurons transmit information?