Alex Di Paola
Introduction to Psychology
In order to even begin to understand
our thoughts and actions, we must first understand the role our biology plays.
More specifically how our neurons communicate with one another. Not all neurons
are the same. Each neuron has a cell body and branching fibers. Bushy dendrite
fibers receive information and transmit the information toward the cell body.
Then, the axon fiber passes the message through its terminal to various parts
of your body. These parts include other neurons, muscles and glands. So, the dendrites
listen to the messages and the axons sends that message to the necessary
target. In order to understand how neurons communicate, it’s important to
understand what action potential is. Action potential is the process of a
neuron sending a message by firing an impulse. Action potential is also the
brief electrical charge that travels down its axon. A neural impulse travels at
various speeds. The speed at which a neuron travels depends on the type of
fiber. The speed ranges from 2 miles per hour to more than 200 miles per hour.
This may sound fast but in comparison to the rate at which electricity is
passed through a wire, the speed is comparably slow. So our ability to react to
an event is not instantaneous. Our reaction compared to a computer is a quarter
of a second slower. This is pretty interesting because our brain is vastly more
complex than a computer and yet the computer can process information much
faster. Neurons are so complex that even with a microscope it would be almost
impossible to tell where one neuron ends and the other begins. In the past,
scientists believed that the axon of one cell fused with the dendrites of
another in an uninterrupted fabric. Sir Charles Sherrington noticed that neural
impulses were taking a long time to travel through a neural pathway. This led to the discovery
that there must be a brief interruption in the transmission. Sherrington then
stated that the meeting point between neurons would be called a synapse. The
axon terminal of one neuron is separated from the receiving neuron. The
synaptic gap is what separates them. Santiago Ramon y Cajal was interested in
the near unions of neurons, calling them “protoplasmic kisses”.
When an action potential reaches the
terminal located at the end of the axon’s end, it triggers the release of
chemical messengers called neurotransmitters. Neurotransmitter molecules cross
the synaptic gap and proceed to bind to receptor sites on the receiving neuron.
Neurotransmitters unlock tiny channels at the receiving site. Electrically
charged atoms then proceed to flow in, exciting or inhibiting the receiving
neurons readiness to fire. The excess neurotransmitters are then drifted away
and are broken down by enzymes. The enzymes are then reabsorbed by the sending
neuron. It’s important to understand how neurotransmitters play an important
role in their ability to affect our moods, memories and mental abilities.
Acetylcholine is one of the best understood neurotransmitters. It plays an
important role within our learning and memory. Acetylcholine is also the
messenger at every junction between motor neurons and various skeletal muscles.
In order to take apart the
influences of environment and heredity, behavior geneticists could use two
different types of experiments. The first would control heredity while at the
same varying the home environment. The second experiment would control the home
environment while varying heredity. These experiments may seem impossible but
by using identical twins, such experiments become possible. There are several
reasons why identical twins would fit the parameters of these experiments.
Identical twins are genetically identical. Some call twins, “Nature’s own human
clones”. They also share the same conception and uterus and usually have the
same birth date and cultural history. Fraternal twins are developed from two
separate fertilized eggs. Since both eggs share the same womb, they share a
prenatal environment but they are genetically no more similar than any brother
and sister. Sharing the same gene has been proved to result in shared
experiences. If one twin develops a disease early on, the other twin has a very
likely chance of obtaining the same disease. To study the effects of genes and
environments, researchers have studied thousands of identical twins. So as you
can see twins have made great research experiments because of the ability to
study genetically identical individuals. With the same genetics, researchers
can focus on how there external environment has impacted their development.
Researchers can also compare the effects of the external environment to each
4.) There are 3 types of major
neurons carry information throughout the nervous system. The first major type
of neurons are the sensory neurons. The sensory neurons carry messages from the
body’s tissues and sensory receptors inward to the brain and spinal cord for
processing. The second type are motor neurons. Motor neurons carry a variety of
instructions from the central nervous system out to the body’s muscles and
glands. The third type are interneurons. Interneurons process information
between the sensory input and the motor output . Human complexity exists mostly
within interneurons. There are billions of interneurons and millions of sensory
and motor neurons. There are several examples to show how sensory neurons
function. One example would be smell/ The sensory neurons which partake in the
action of smelling are known as olfactory receptor neurons. These receptor
neurons correspond to the odor molecules in the air.
Brain plasticity is the brain’s
ability to modify itself after the brain has been damaged. Some brain damage
effects may vary. Severed brain and spinal cord neurons do not regenerate.
Also, some brain functions seem preassigned to very specific areas of the
brain. The text talks about a newborn who suffered damage to the temporal lobe
facial recognition areas. The newborn remained unable to recognize faces. Some
neutral tissue can recognize in response to damage. Under the surface of our
awareness, the brain is constantly being altered as it adjusts to new
experiences. Plasticity may also occur after serious damage. In young children,
blindness or deafness makes unused brain areas available for other uses. For
example, the text talks about how if a blind person uses one finger to read
Braille, the brain area dedicated to that finger expands as the sense of touch
invades the visual cortex that normally helps people see.
Genes can either be active or
inactive. Epigenetics studies the molecular mechanisms by which environments
can trigger or block genetic expression. Epigenetic marks are created by our
experiences. These are more often organic methyl molecules attached to part of
a DNA strand. If a markinstructs the cell to ignore a gene present in the DNA
segment, those genes will turn off. Meaning they will prevent the DNA from
producing the proteins coded by that gene. Epigenetic molecules can be affected
by environmental factors. These factors include diet, drugs and stress. These
epigenetic molecules regulate gene expression.