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Introduction to Biopsychology
Adapted From What is Biopsychology? and What is a Neuron?
By Kendra Cherry, Psychology Expert
http://psychology.about.com/od/biopsychology/a/biopsyc.htm
Biopsychology is a branch of psychology that analyzes how the brain and neurotransmitters influence our
behaviors, thoughts and feelings. This field can be thought of as a combination of basic psychology and
neuroscience.
Many psychology programs use alternate names for this field, including biopsychology, physiological
psychology, behavioral neuroscience and psychobiology. Biopsychologists often look at how biological
processes interact with emotions, cognitions and other mental processes. The field of biopsychology is related
to several other areas including comparative psychology and evolutionary psychology.
If you are interested in the field of biopsychology, then it is important to have an understanding of biological
processes, anatomy and physiology. Three of the most important components to understand are the brain,
neurotransmitters and the nervous system.
The Brain and Nervous Systems
The Central Nervous System is composed of the brain and spinal cord. It receives sensory information
and controls the body's responses. The CNS is differentiated from the peripheral nervous system, which
involves all of the nerves outside of the brain and spinal cord that carry messages to the CNS.
The peripheral nervous system (PNS) is the division of the nervous system containing all the nerves that lie
outside of the central nervous system (CNS). The primary role of the PNS is to connect the CNS to the
organs, limbs and skin. These nerves extend from the central nervous system to the outermost areas of the
body.
The nerves that make up the peripheral nervous system are actually the axons or bundles of axons from
neuron cells. In some cases, these nerves are very small but some nerve bundles are so large that they can be
easily seen by the human eye.
Another important part of the nervous system is the Peripheral Nervous System, which is divided into
two parts:
1. The Somatic Nervous System: Controls the actions of skeletal muscles.
2. The Autonomic Nervous System: Regulates automatic processes such as heart rate, breathing, and
blood pressure. There are two parts of the autonomic nervous system:
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The Sympathetic Nervous System: Controls the "fight or flight" response. This reflex prepares
the body to respond to danger in the environment.
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The Parasympathetic Nervous System: This system works to bring your body back to its
normal state after a fight or flight reflex.
The Somatic Nervous System
The somatic system is the part of the peripheral nervous system responsible for carrying sensory and motor
information to and from the central nervous system. The somatic nervous system derives its name from the
Greek word soma, which means "body." The somatic system is responsible for transmitting sensory
information as well as for voluntary movement. This system contains two major types of neurons: sensory
neurons (or afferent neurons) that carry information from the nerves to the central nervous system, and
motor neurons (or efferent neurons) that carry information from the brain and spinal cord to muscle fibers
throughout the body.
The Autonomic Nervous System
The autonomic system is the part of the peripheral nervous system responsible for regulating involuntary body
functions, such as blood flow, heartbeat, digestion and breathing. This system is further divided into two
branches: the sympathetic system regulates the flight-or-fight responses, while the parasympathetic system
helps maintain normal body functions and conserves physical resources.
The Brain
The outermost part of the brain is known as the cerebral cortex. This portion of the brain is responsible
for functioning in cognition, sensation, motor skills, and emotions.
The brain is comprised of four lobes:
1. Frontal Lobe: Also known as the motor cortex, this portion of the brain is involved in motor skills,
higher lever cognition and expressive language.
2. Occipital Lobe: Also known as the visual cortex, this portion of the brain is involved in interpreting
visual stimuli and information.
3. Parietal Lobe: Also known as the somatosensory cortex, this portion of the brain is involved in
the processing of other tactile sensory information such as pressure, touch and pain.
4. Temporal Lobe: Also known as the auditory cortex, this portion of the brain is involved in the
interpretation of the sounds and language we hear.
What is a Neuron?
A neuron is a nerve cell that is the basic building block of the nervous system. Neurons are similar to other
cells in the human body in a number of ways, but there is one key difference between neurons and other cells.
Neurons are specialized to transmit information throughout the body.
These highly specialized nerve cells are responsible for communicating information in both chemical and
electrical forms. There are also several different types of neurons responsible for different tasks in the human
body.
Sensory neurons carry information from the sensory receptor cells throughout the body to the brain. Motor
neurons transmit information from the brain to the muscles of the body. Interneurons are responsible for
communicating information between different neurons in the body.
Neurons vs. Other Cells
Similarities with other cells:
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Neurons and other body cells both contain a nucleus that holds genetic information.
Neurons and other body cells are surrounded by a membrane that protects the cell.
The cell bodies of both cell types contain organelles that support the life of the cell, including
mitochondria, Golgi bodies, and cytoplasm.
Differences that make neurons unique:
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Unlike other body cells, neurons stop reproducing shortly after birth. Because of this, some parts
of the brain have more neurons at birth than later in life because neurons die but are not replaced.
While neurons do not reproduce, research has shown that new connections between neurons
form throughout life.
Neurons have a membrane that is designed to sends information to other cells.
The axon and dendrites are specialized structures designed to transmit and receive information.
The connections between cells are known as a synapses. Neurons release chemicals known as
neurotransmitters into these synapses to communicate with other neurons.
The Structure of a Neuron
There are three basic parts of a neuron: the dendrites, the cell body and the axon. However, all neurons vary
somewhat in size, shape, and characteristics depending on the function and role of the neuron. Some neurons
have few dendritic branches, while others are highly branched in order to receive a great deal of information.
Some neurons have short axons, while others can be quite long.
The longest axon in the human body extends from the bottom of the spine to the big toe and averages a
length of approximately three feet!
Learn more about the structure of a neuron.
Action Potentials
How do neurons transmit and receive information? In order for neurons to communicate, they need to
transmit information both within the neuron and from one neuron to the next. This process utilizes both
electrical signals as well as chemical messengers.
The dendrites of neurons receive information from sensory receptors or other neurons. This information is
then passed down to the cell body and on to the axon.
Once the information as arrived at the axon, it travels down the length of the axon in the form of an electrical
signal known as an action potential.
Communication Between Synapses
Once an electrical impulse has reached the end of an axon, the information must be transmitted across the
synaptic gap to the dendrites of the adjoining neuron. In some cases, the electrical signal can almost
instantaneously bridge the gap between the neurons and continue along its path.
In other cases, neurotransmitters are needed to send the information from one neuron to the next.
Neurotransmitters are chemical messengers that are released from the axon terminals to cross the synaptic
gap and reach the receptor sites of other neurons. In a process known as reuptake, these neurotransmitters
attach to the receptor site and are reabsorbed by the neuron to be reused.
Neurotransmitters
A neurotransmitter is a chemical messenger that carries, boosts and modulates signals between neurons and
other cells in the body. In most cases, a neurotransmitter is released from the axon terminal after an action
potential has reached the synapse. The neurotransmitter then crosses the synaptic gap to reach the receptor
site of the other cell or neuron. Then, in a process known as reuptake, the neurotransmitter attaches to the
receptor site and is reabsorbed by the neuron.
Neurotransmitters are an essential part of our everyday functioning. While it is not known exactly how many
neurotransmitters exist, scientists have identified more than 100 of these chemical messengers.
What effects do each of these neurotransmitters have on the body? What happens when disease or drugs
interfere with these chemical messengers? The following are just a few of the major neurotransmitters, their
known effects, and disorders they are associated with.
Acetylcholine: Associated with memory, muscle contractions, and learning. A lack of acetylcholine in the
brain is associated with Alzheimer’s disease.
Endorphins: Associated with emotions and pain perception. The body releases endorphins in response to
fear or trauma. These chemical messengers are similar to opiate drugs such as morphine, but are significantly
stronger.
Dopamine: Associated with thought and pleasurable feelings. Parkinson’s disease is one illness associated
with deficits in dopamine, while schizophrenia is strongly linked to excessive amounts of this chemical
messenger.
Types of Neurotransmitters
Neurotransmitters can be classified by function:
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Excitatory neurotransmitters: These types of neurotransmitters have excitatory effects on the
neuron; they increase the likelihood that the neuron will fire an action potential. Some of the
major excitatory neurotransmitters include epinephrine and norepinephrine.
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Inhibitory neurotransmitters: These types of neurotransmitters have inhibitory effects on the
neuron; they decrease the likelihood that the neuron will fire an action potential. Some of the
major inhibitory neurotransmitters include serotonin and GABA.
Some neurotransmitters, such as acetylcholine and dopamine, can both excitatory and inhibitory effects
depending upon the type of receptors that are present.