How Many Neurons Does the Human Being Have?

It is estimated that the human brain has a number of about 86 billion neurons. It is a figure that was estimated in a 2009 scientific investigation in which scientists used a new methodology.

The number is then close to the 200-400 billion stars in the Milky Way, but it is not the same. On the other hand, until recently it was thought that neurons cannot regenerate, however it seems that in most mammals they do so in the hippocampus and the olfactory bulb through neurogenesis..

Article index

• 1 Very brief explanation of the functioning of neurons
• 2 In babies
• 3 The importance of experience
• 4 Can neurons regenerate?
• 5 Processes that lead to the death of neurons
• 6 Fun facts
• 7 Number of neurons in other animals
• 8 References

Very brief explanation of the functioning of neurons

The neuron is made up of three main parts: the soma, the dendrites (there are usually several) and the axon.

All electrochemical messages cause thousands of neurons to fire at the same time and transmit the message to neighboring neurons. This connection occurs between the axon of one neuron with the dendrites of another and is called a synapse..

Each neuron communicates in this way with hundreds of neurons receiving electrical charges at a speed of 0.001 seconds, which can occur up to 500 times per second. The most curious thing is that the number of discharges and the value of each one constitute the language of neurons.

In babies

The brain of a newborn has more than 100 billion neurons, many more than it really needs. However, he still lacks dendrites that he will have to develop in the future and which will be the first reason for weight gain..

In the first years of growth, there is a growth of axons and dendrites and synapses are produced, especially in the cerebral cortex.

In the first 2 years of life, up to 15,000 new neuronal connections can be formed, reaching 100 billion synapses..

Later, there is a pruning process whereby neurons that are not used and dendrites that do not connect atrophy and die..

Throughout life, neurons continue to form and die, and new synaptic connections are made, but the speed is not the same as just after birth.

The importance of experience

The development of neurons and their connections does not depend only on genetics and the pre-established; it also depends on its use. That is, if there are no experiences that make neurons and their connections activate, they will be lost..

However, the death of some neurons can benefit the development of others and it is believed that the child's development is due in part to this process.

For example, in fragile X syndrome, children who have it have dense and very long dendrites, in which the loss process has not occurred (also called neuronal pruning)..

Can neurons regenerate?

Yes, recent research has shown that damaged areas of the brain can regenerate from cells that become neurons.

Likewise, the adult human brain can generate new neurons and of course connections.

Diet, physical exercise and mental exercise (for example with cognitive stimulation) are essential to maintain a healthy brain.

Processes that lead to the death of neurons

The brain loses about 10,000 neurons per day and if you have a bad diet, abuse alcohol or other drugs, the number is much higher.

• Up to 1,000,000 neurons can be lost in a binge.
• Stress prevents the new formation of neurons and even kills them.
• Hypertension can cause the death of neurons.
• Alcohol and smoking tobacco or marijuana also cause the death of neurons.
• The drugs.

Fun facts

-The brain constitutes 2% of the body's weight, although it consumes 20% of the energy.

-The brain receives 36 liters of blood every hour, 891 liters per day.

-If the blood supply to the brain is interrupted, consciousness is lost within a few seconds.

-The brain needs 8-12 glasses of water for proper function. 

-The cell body of the neuron has the ability to move, but most remain stable (They extend the axons).

Number of neurons in other animals

• Sea sponge - 0.
• Medusa - 800.
• Leech - 10,000.
• Snail - 10,000.
• Fruit fly - 100,000.
• Lobster - 100,000.
• Ant - 250,000.
• Cockroach - 100,000.
• Frog - 16,000,000.
• Mouse - 71,000,000.
• Dog - 160,000,000.
• Rat - 200,000,000.
• Cat - 300,000,000.
• Octopus - 300,000,000.
• Macaque - 480,000,000.
• Capuchin monkey - 600,000,000-700,000,000.
• Horse - 1,200,000,000.
• Fin Whale - 1,500,000,000.
• Pilot Whale - 3,000,000,000.
• Gorilla - 4,300,000,000.
• Dolphin - 5,800,000,000.
• Chimancé - 6,200,000,000.
• Orca - 10,500,000,000.
• African Elephant - 11,000,000,000.

References

-http://en.wikipedia.org/wiki/List_of_animals_by_number_of_neurons

-http://www.ncbi.nlm.nih.gov/pubmed/19226510