Reflexes
If you touch something very hot, your hands pulls away almost instantly, without waiting for your brain to tell it to. This is an example of a reflex - a rapid reaction that helps to protect you from injury. A massage flashes from your hand to your spinal cord - the bundle of nerve cells running down your body. The message is then passed straight to motor nerves, which make your arm muscles contract.
Reflex actions happen automatically, and often do not involve signals from the brain.
Deliberate actions - such as picking a paper, are triggered by signals from the brain.
Sensitive parts
All over your body, you have nerve ending that give you information about the things you touch. Instead of being spread out, they are concentrated in places where the sense of touch is most useful. The parts of the body that have the most nerve endings are drawn enlarged. The most sensitive parts are the mouth and fingertips, while the least sensitive are the backs of the arms and legs. You can prove this by closing your eyes, and asking a friend to touch your skin gently in sensitive areas with a pencil or paintbrush.
The gentle touch
Extra sensitive hands and fingertips help us to adjust our grip when we pick things up.
Tag :reflexes
Saturday, January 5, 2008
Wednesday, December 26, 2007
All in the mind
Your brain is divided into three main parts. Two of them called the brain stem and the cerebellum, control essential processes such as breathing, and keep all the parts of your body working together. The third part is much bigger, and allows you to sense things, think, and make your body move.
Brain functions
Seeing the world : Several areas of your brain are involved in interpreting signals from the optic nerves in your eyes.
Tuning in : The area that deals with interpreting sounds, called the auditory area, receives signals from nerves in your ears.
Fine control : Whenever you make complicated movements, for example when using a keyboard, the part called the premotor area helps to control your muscles.
Thinking and understanding : The front of the brain is where thinking takes place. The ability to think makes us aware that we exist. The two side work in slightly different ways. In most people, the "right side" deals with shapes and feelings.
Feeling your body : The area of the brain that receives signals from nerves in the skin is called the sensory area. It allows you to feel pressure, heat, cold and pain.
Making movement : The area of the brain that sends out signals telling muscles to contract when you decide to move is called the motor area.
Dealing with words : The speech area controls the muscles you use when you talk. A nearby part of the brain helps you to understand words when people speak to you.
Left side : The left side of the brain deals with logical matters, such as maths.
Tag :brain functions
Your brain is divided into three main parts. Two of them called the brain stem and the cerebellum, control essential processes such as breathing, and keep all the parts of your body working together. The third part is much bigger, and allows you to sense things, think, and make your body move.
Brain functions
Seeing the world : Several areas of your brain are involved in interpreting signals from the optic nerves in your eyes.
Tuning in : The area that deals with interpreting sounds, called the auditory area, receives signals from nerves in your ears.
Fine control : Whenever you make complicated movements, for example when using a keyboard, the part called the premotor area helps to control your muscles.
Thinking and understanding : The front of the brain is where thinking takes place. The ability to think makes us aware that we exist. The two side work in slightly different ways. In most people, the "right side" deals with shapes and feelings.
Feeling your body : The area of the brain that receives signals from nerves in the skin is called the sensory area. It allows you to feel pressure, heat, cold and pain.
Making movement : The area of the brain that sends out signals telling muscles to contract when you decide to move is called the motor area.
Dealing with words : The speech area controls the muscles you use when you talk. A nearby part of the brain helps you to understand words when people speak to you.
Left side : The left side of the brain deals with logical matters, such as maths.
Tag :brain functions
Friday, December 14, 2007
How do we remember things?
Scientist are still not certain how the brain remembers things, but they have produced a likely explanation. They know that each cell in the brain is connected to thousands of other cells via connection points called synapses. They think that the brain stores new information by forming new sets of connections between cells, it is as if the cells in the brain are constantly being rewired. At first, information is stored in your short-term memory. The information is then transferred into your long-term memory, which can store it for days, months or even years.
Lost forever
Unlike other cells in your body, the cells in your brain cannot be replaced when they get worn out. As a result, the number of cells in your brain steadily decreases as you get older.
Tag :memory
Scientist are still not certain how the brain remembers things, but they have produced a likely explanation. They know that each cell in the brain is connected to thousands of other cells via connection points called synapses. They think that the brain stores new information by forming new sets of connections between cells, it is as if the cells in the brain are constantly being rewired. At first, information is stored in your short-term memory. The information is then transferred into your long-term memory, which can store it for days, months or even years.
Lost forever
Unlike other cells in your body, the cells in your brain cannot be replaced when they get worn out. As a result, the number of cells in your brain steadily decreases as you get older.
Tag :memory
Wednesday, December 5, 2007
How do nerves work?
Most nerves cells have a long thread, called an axon, which works partly like a battery and partly like a wire. When the nerves is resting, the axon is charged with electricity, just like the terminals of a battery. When the nerves is triggered into action, the charge suddenly changes, creating a signal that flashed down the axon. The nerves that the signals pass along to tell muscles to contract are called 'motor nerves. The nerves that carry messages from sense organs to your brain are called 'sensory' nerves. Signals travel along nerves at about 360 km/h (225 mph), fast enough to travel from your brain to your toes in less than 1/50 of a second.
Tag :nerves work
Most nerves cells have a long thread, called an axon, which works partly like a battery and partly like a wire. When the nerves is resting, the axon is charged with electricity, just like the terminals of a battery. When the nerves is triggered into action, the charge suddenly changes, creating a signal that flashed down the axon. The nerves that the signals pass along to tell muscles to contract are called 'motor nerves. The nerves that carry messages from sense organs to your brain are called 'sensory' nerves. Signals travel along nerves at about 360 km/h (225 mph), fast enough to travel from your brain to your toes in less than 1/50 of a second.
Tag :nerves work
Thursday, November 29, 2007
BRAIN AND NERVOUS SYSTEM
Every second, whether you are awake or fast asleep, your is busy processing information. It receives millions of signals from all parts of the body, and its sends out signals that control the way your body works. These signals travel along nerves, bundles of cells that conduct tiny bursts of electricity. The brain itself contain more than 1000 billion nerve cells, and when they are busy these cells generate enough electrical energy to power a light bulb.
Unlike other cells in your body, the cells in your brain cannot be replaced when they get worn out. As a result, the number of cells in your brain steadily decreases as you get older.
Tag :brain
Unlike other cells in your body, the cells in your brain cannot be replaced when they get worn out. As a result, the number of cells in your brain steadily decreases as you get older.
Tag :brain
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