Question

The Human Brain

1

In 1906, Santiago Ramón y Cajal, a Spanish artist and scientist considered to be the father of modern neuroscience, called the brain “a world consisting of a number of unexplored continents and great stretches of unknown territory.” It was true then, and it’s still true today: There is a lot about the brain that scientists do not yet understand. However, what we do know is that the human brain is truly impressive. Although it weighs only about three pounds, it controls everything a person does, ever has done, and ever will do—physically, intellectually, and emotionally. The brain controls a person’s actions, reactions, and survival functions, such as breathing. It also has the ability to think, remember, process information, and learn new things. No computer even comes close to having the brain’s abilities.

2

The brain is one part of the central nervous system—the system that controls all of the body’s activities. The central nervous system is made up of the brain and the spinal cord. The brain is protected by the skull, and the spinal cord runs through vertebrae—the bones that make up the spine. The spinal cord transmits messages between the brain and other parts of the body through nerve cells called neurons. If a person decides to pick up a book from a shelf—a voluntary action—the brain sends that message to the arm and hand through the spinal cord. And if a person touches a hot surface and burns their hand—an involuntary action—the nerve cells in the hand send a pain message to the brain through the spinal cord.

3

A constant stream of messages travels through the neurons in the spinal cord, at speeds of more than 150 miles per hour (Arlen 223). The human brain never stops working, even when a person is asleep. In addition to transmitting messages through the spinal cord, neurons transmit messages from one part of the brain to another. There are approximately 86 billion of these cells in the brain alone. Neurons send messages through tiny branch-like structures that connect to other neurons in different parts of the brain and throughout the body. The points where neurons meet and transmit information to each other are called synapses. Each neuron may be connected to as many as 10,000 other neurons, resulting in more than 100 trillion synapses in a single brain.

4

Although a person cannot increase the number of neurons in their brain, learning new things increases the number of synapse connections between neurons. Education can actually change the structure of the human brain; that structure changes every time a person learns or has a new thought or memory. The more a person learns, the more there is to think about. And the more there is to think about, the more there is to remember. As a result, the connections between neurons get stronger, and the brain is able to function more effectively. It processes, thinks, analyzes, and stores information more quickly and efficiently than it did before these connections were made. Everything a person knows is the result of the connections between neurons.

5

Cajal’s studies in the late nineteenth and early twentieth centuries established the existence of neurons, the basic building block of the body’s nervous system—and of most theories we have about the brain. Today, new discoveries continue to increase our knowledge of how the brain functions and how people learn. But will we ever truly understand the human brain? In other words, will the human brain ever be able to truly understand itself?: write down 5 detail that observation

Answer 1

1. The human brain weighs about three pounds but controls all physical, intellectual, and emotional functions (para 1).
2. The brain and spinal cord make up the central nervous system; the brain is protected by the skull and the spinal cord runs through vertebrae (para 2).
3. The brain contains about 86 billion neurons, and each neuron can connect to as many as 10,000 others, producing over 100 trillion synapses (para 3).
4. Learning does not increase neuron number but increases synaptic connections and changes the brain’s structure, strengthening connections and improving function (para 4).
5. Neuronal messages travel very fast (more than 150 miles per hour), and the brain never stops working—even during sleep (para 3).