Ions then flow into the receiving cell and this creates a new electrical message [ 2 ]. This is also how our neurons communicate with our muscles, telling us when to move. The synapse between a nerve cell and a muscle cell is called the neuromuscular junction Figure 2B [ 3 ]. The neurotransmitter released in the neuromuscular junction is called acetylcholine.
Just like in neurons, the binding of acetylcholine causes channels to open in the muscle cell, allowing ions to flood into the muscle [ 3 ]. This electrical message causes the muscle to contract or shorten.
Think about catching a ball: your brain tells a neuron to send an electrical signal to the neuromuscular junction synapse, and this causes neurotransmitter to be released in your finger muscles, so that they contract to catch the ball. Our senses detect the world around us and transform the many external forms of energy light, sound, movement into electrical messages in our neurons. In our eyes, for example, there are light-detecting neurons that respond to the things we see [ 1 ]. Some of these special neurons detect colored light red, green, blue and some detect just black and white, like an old-fashioned photograph.
Light causes channels to open in light-detecting neurons, which sends an electrical message to the synapses of neurons inside your brain Figure 3 [ 1 ]. This information is then processed by the brain to interpret the light images. For us to hear, sensory receptors in our ears are activated by sound vibrations traveling through the air. These air vibrations move tiny hairs on the ear neurons [ 1 ]. This movement opens channels, allowing ions to flood into the neuron and create the electrical message.
As a result, neurotransmitters are released at the synapse between the hair cell and a brain neuron. The loudness of the sound depends on how many hairs are bent. Greater bending causes more neurotransmitter to be released at the synapse, which then creates more electrical messages into the brain. These signals travel to brain neurons which interpret them as smells [ 1 ].
One of the most important things about our brains is that the number and size of synapses change when we use them. This property of the brain to change in response to what we experience is called plasticity. Plasticity allows us to learn new information and then to remember what we have learned [ 2 ]. If we use our synapses a lot, many more can form. If we do not use them as much, synapses can shrink or decrease in number [ 2 ]. The strength of communication between synapses can also change depending on how much we use them.
If we use them a lot, this can increase the amount of neurotransmitter released, or the number of neurotransmitter receptors on the receiving cell [ 2 ]. Synapses are like muscles; they are strengthened by use. If we use our synapses a lot, it can create new, strong synapses that remain in place for many years, even decades [ 2 ]. This can help us to form long-term memories. Since your synapses are so important for moving, sensing, learning, and remembering, it is easy to see how problems with synapses can cause diseases and disabilities [ 4 , 5 , 6 ].
When synapses do not work properly, the brain cannot communicate within itself and with the muscles. The light bouncing off the trees enters your open eyes; the chirping sounds of the birds reach your ears; and the damp smell of the forest soil wafts up your nose. The nerve cells in your eyes, ears and nose detect these sensations, and send signals to different parts of your brain, which turn them into what you see, hear and smell — all in a matter of milliseconds.
As well as sending electrical signals through the nervous system, the brain also uses chemical signals to control processes in the body. Have you ever wondered why you feel sleepy? When the sun goes down, a part of your brain called the pineal gland produces a hormone called melatonin, which makes you feel tired. Melatonin is produced a few hours later in teenagers than it is in adults and children. This makes teenagers want to go to bed and wake up later than adults and children. Read more: The biological reason why it's so hard for teenagers to wake up early for school.
But research has shown that when people think they are being watched by others, certain parts of their brains are busy. The human brain, with its billions of neurons working together, is sending signals to your body to determine how you feel, from one moment to the next.
The brain is always trying to find ways to explain the sensations that we feel in our body. Wellcome Trust. Electrifying the Brain. Interact with the Brain. Best of BrainFacts Newsletter Our editors' picks from this month's articles. Core Concepts A beginner's guide to the brain and nervous system. Like Subscribe Follow Follow Subscribe.
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