Biopsychology

Mind-Body Connection Most experts in the field of psychology and biology agree that the mind and body are connected in more complex ways than we can ever comprehend. Research constantly shows us that the way we think affects our behavior, feelings, and our body’s response. The opposite is also true – physical illness, physical exhilaration, exercising, insomnia, among other physical activities affect the way we feel and behave, but also the way we think about ourselves and the world.

Mind-Body Connection Since most of this online class is devoted to the way our mind works (as opposed to our biology), this chapter will focus on the neuron, the nervous system, and how these physiological components of our being interact, respond to, and influence our psychological health.

Neuron The neuron is the basic building block of the nervous system, which is the body’s primary communication network. The nervous system gathers and processes information from the environment and allows you to act on the environment. The neuron’s basic task is to communicate with in and with other neurons.

The Neuron

Neuron Neurons vary greatly in size and shape, depending on their specialized function: -Human brain  100 billion neurons -brain tissue  rice grain -10,000 neurons Neurons are simple “cheap” structures, but highly specialized.

Neuron The neuron is comprised of three basic components: Dendrites Cell body or soma Axon

Dendrites Dentrites receive information from other neurons In Greek, dendrites mean branches, hence, they are like extensive tree branches. The more branches, the more information a neuron can receive.

Soma or Cell Body The soma, or more commonly referred to as the cell body, sums and subtracts the information it receives from the dendrites. It also contains the nucleus, which provides energy for neurons to carry out their function.

Stimulus threshold In order for a neuron to fire it’s message, it must reach “stimulus threshold.” Stimulus threshold is the minimum amount of information needed for the neuron to fire. For example, your friend is talking in a low voice, so low that you don’t even hear it. Stimulus threshold is the lowest your friend can talk to you so that you actually pick up the sound, which is why the definition states that it is the minimum amount of information.

The Axon The Axon sends messages to other neurons and parts of body (ie. glands, muscles). Unlike the dendrites, there is only one axon, which varies in length (few thousandths of inch to base of spine to big toe).

Action Potential The firing of the message down the axon is called “action potential.” It occurs in an “all-or-none” process, which means either the message is sent or not sent. For example: imagine dominos are lined up perfectly, if you tap the first domino, they either all fall down or none of them fall down.

Action Potential Let’s go back to the example of your friend whispering. The louder your friend talks to you, the faster the action potential (or message) will be sent to the appropriate brain region so that it can process this auditory information.

Myelin Sheath To help transmit the message or action potential down the axon, “myelin sheath” insulates the axon. Myelinated axons speed neuronal transmission by about 15 times. Most neurons are myelinated, however, not all.

Myelin Sheath Myelinated axons are responsible for making our bodily movements smooth. If myelinated axons start to degenerate, then degenerative diseases, such as multiple sclerosis or Parkinson’s disease occurs, where movement is much more jagged.

Axon Terminals At the end of the axon are axon terminals or terminal buttons. They contain neurotransmitters.

Neurotransmitters Neurotransmitters are chemical messengers that cross the small space between two neurons called the synapse. Then the neurotransmitters attach to receptor sites (on the dendrites) of the surrounding neurons. These are the chemicals in the brain that doctors often refer to people with mental illnesses as having “chemical imbalances.” What they are essentially saying is that there is either too much or too little of a particular chemical or neurotransmitter needed for optimal health.

Here are close-up pictures of the action potential traveling down the axon to the axon terminals (pic. a), releasing the neurotransmitters across the synapse (pic. b), to connect onto receptor sites of other neurons (pic. c).

Neurotransmitter molecules have specific shapes; Receptor molecules have binding sites and must fit together like a “lock-and-key.”

Let’s look at five ways drugs can affect neural transmission, which can help bring balance back to the neurotransmitters: First, drugs can increase or decrease the amount of neurotransmitter released by the neurons. Second, drugs can affect the length of time the neurotransmitter remains in the synaptic gap, either increasing or decreasing the amount available to the postsynaptic receptor.

Five ways drugs can affect neural transmission: Third, drugs can prolong the effects of the neurotransmitter by blocking its reuptake by the sending neuron. Reuptake is the process where the neurotransmitters that are not used, are reabsorbed into the sending neuron (the neuron that the neurotransmitters came from).

Let’s look at the five ways drugs can affect neural transmission: Fourth, drugs can mimic specific neurotransmitters. This would create an increase of the neurotransmitters. Fifth, drugs can mimic or block the effect of a neurotransmitter by fitting into receptor sites and preventing the neurotransmitter from acting.

One example of a neurotransmitter is serotonin. Serotonin is responsible for sleep, moods, and emotional states. Too much serotonin in the system may cause Autism and too little may cause anxiety and mood disorders.

Hence, if a person is experiencing depression, the drug prescribed is some form of: Serotonin-reuptake inhibitor, known as SSRIs (this ties into our 3rd point on our list of how drugs affect neural transmission). For example, Prozac (which is a form of SSRI) works by keeping serotonin in the synapse longer, giving it more time to exert an effect, increasing the amount of serotonin in a person’s system.

For the purpose of this class, you will not be responsible for remembering the specific neurotransmitters and their function; however, you will be responsible for knowing the five ways drugs affect neural transmission.

Conclusion We can use our bodies as maps as to what is going on for us physically, psychologically, and emotionally. When the body experiences stress, the system can become imbalanced. Western medicine uses medication to help restore balance. As students of psychology, it is also important to process our emotions, heal our past, and become aware of our thoughts to experience the most profound and holistic changes possible.