HOW THE BRAIN WORKS
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How does the brain work?
Everybody has a brain and this major organ plays a part
in everything you do from the time you are born throughout your entire life.
Every action, every word, even the smallest decisions are all a result of the
brain performing its intended function. What may be even more amazing about the
brain is that not only does every one person have one, but every living animal
has one as well. The human brain is much more complex than the brain of any
other species and the way it works is truly fascinating.
Although the brain is only the approximate size of
a small head of cauliflower, it plays a major role in every function of the
human body. It controls the body’s temperature, blood pressure, heart rate, and
breathing. It also controls the five different senses of sight, smell, touch,
hearing, and tasting. In this way, it allows you to experience the world. Not
only does it control the physical aspect of the body such as walking and
talking, it also controls the emotional aspects, such as thinking, feeling, and
Neuroscience is the complex study of the brain,
spinal cord, and peripheral nerves. This complex system is the neurological
system and controls information both internally, meaning things that are
happening inside the body such as temperature, and externally, meaning things
that are taking place outside the body, such as hearing music or touching
someone’s hand. The totality of the brain’s role is extremely complex but the
most basic functions it performs are motor control, processing visual stimuli,
auditory stimuli, different sensations, and memory and emotional functions.
The first thing to understand when discussing the
brain is the function of neurons and what they are made of as well as the
different types of neurons. The entire brain is made up of neurons, which are
nerve cells. One brain has approximately 100 billion of these neurons. It is
these neurons that collect and distribute information through electrochemical
signals. These cells are built like other cells in the body but the fact that
they have electrochemical elements means that they can send messages over long
Neurons are made up of three different parts. The
cell body, the axon, and the dendrites, or nerve endings. The cell body holds
the nucleus, which contains DNA, the endoplasmic reticulum, which develops
proteins, and mitochondria, which creates energy. The axon is a long branch
extending from the cell body. These long branches are what carry the
electrochemical signal to the cell. Some axons are covered with myelin, which is
a layer of fat to help the axon carry the signal more quickly. Dendrites are at
one or both ends of the cell and are a way of allowing the different cells to
communicate with each other. It is dendrites that are also responsible for
analyzing and understanding the environment.
These parts that make up a neuron have four
different types. Sensory neurons are responsible for carrying external signals
from the outer parts of the body (the periphery) to the central nervous system.
Motor neurons do the opposite. They take signals from the central nervous system
and take them to the outer parts of the body such as the glands, the muscles,
and the skin. Receptors analyze the environment, such as light and sound, and
the sensory neurons carry and communicate the information they receive from the
receptors. Interneurons connect these different neurons of the brain and the
spinal cord and make them one cohesive unit.
These neurons travel along paths and the simplest type of path is the
monosynaptic reflex pathway. This is one single connection and the knee-jerk
reaction works on this type of pathway. When the doctor bangs on the reflex in
the knee with a rubber hammer, the receptors analyze this action and send it to
the sensory neurons. The sensory neuron then carries the message to the motor
neuron that handles the leg muscles. The nerve impulses in this motor neuron are
what cause the leg to respond to the stimuli. This action is really quite simple
and is called a hard-wire reflex. There are multiple hard-wired reflexes within
the human body, none of which require the brain to work. As the pathways become
more complex, the brain must get involved to ensure that functioning will happen
Along with understanding neurons, it’s important to
understand the different parts of the brain to understand how it really works.
There are four major components that make up the brain. The brain stem is
comprised of the medulla, which is the uppermost part of the spinal cord, pons
and midbrain. It is the brain stem that leads the reflexes and major functions,
such as heart rate, blood pressure, and temperature. It also controls how the
limbs move and the visceral functions, such as when food is digested and
The cerebellum takes the information from the
vestibular system and using this information, interprets movement. With this
information, the limbs move accordingly. The hypothalamus and pituitary gland
work in commanding the visceral functions and in turn, creating a behavioral
reaction. The cerebrum is also called the cortex or the cerebral cortex and is
comprised mainly of large fiber tracts, and other complex structures. It is the
cerebrum that gathers information from all of the sensory organs and starts the
motor functions. It is also responsible for emotions, and keeps memory and
The lower brain is a basic system that is comprised
of the brain stem, the spinal cord and the diencephalon. Each of these parts of
the lower brain contain nuclei that are responsible for particular functions.
The medulla contains nuclei that control blood pressure and breathing transmits
the information from the cranial nerves to the sensory nerves. The pons holds
nuclei that carry movement and position signals from the cerebellum to the
cortex. The midbrain has nuclei that connects the different sections of the
brain that are responsible for motor functions, eye movements, and controls the
auditory senses. The substantia nigra area of the midbrain controls voluntary
movements. When it ceases to function, Parkinson’s Disease sets in.
The thalamus delivers the sensory pathways to
different parts of the cortex. The thalamus also determines which information
will actually be delivered to the consciousness and also plays a part in the
trading of motor information with the cerebellum, basal ganglia, and the cortex.
The nuclei in the hypothalamus issue hormonal secretions from the pituitary
gland. The hypothalamus participates in almost every behavioural reaction,
including sexual reproduction, eating, growth, and lactation.
The cerebellum is divided into many different lobes
and is placed just above and behind the pons. The spinal cord takes information
from the sensory input of the spinal cord, the motor input from the cortex and
basal ganglia, and the position information from the vestibular system. The
cerebellum receives all of this information and coordinates it to the motor
pathways moving away from the brain to control movements. This is why pointing
your finger is done in one motion. If the cerebellum were to be compromised in
any way, the pointing finger would be accomplished through a very jerky motion.
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