The Nervous System

All Biological behavior, both conscious and unconscious, comes from the nervous system. It sends signals all over the body at a cellular level which impact voluntary behavior, involuntary behavior, heightened arousal, energy conservation, and the brain.  There are 2 subsystems that make up the overall nervous system, the Peripheral and the Central Nervous System. An important note about the nervous system, you can get an entire degree in neuroscience, so there is a lot of information.  In order to pass the EPPP you do not need to know the nervous system in great depth, but you do need to understand the basics (and there is a lot of information to just understand the basics). The topic of Biological Bases of Behavior is weighted at 12%, and there is a wide variety of information to know in this topic, so know enough to have a good grasp of how our biology is related to human behavior and disorders, and some of the methods to biologically treat these disorders. The information is best used in collaboration with your own knowledge and what you have already been taught, your previous notes or textbooks, and research if you need more information on a particular topic.  Or you could check out the product reviews page.

Cells

There are 2 main types of cells, Neurons and Glialneuron Cells.  Glial cells primarily support the neurons, hold them in place, create myelin (Provides insulation and allows neurons to fire quicker), and maintain homeostasis. Neurons differ from most other cells as they communicate by utilizing synapses which allow signals to transmit rapidly between cells (either electrical or chemical).  Many neurons have an axon, which when bundled together create nerves.  Not all neurons perform the same function and they specialize in different areas, such as sensory neurons and motor neurons.

The Peripheral Nervous System

The nervous system is divided into 2 parts, the peripheral nervous system (PNS) and the central nervous system (CNS).  Unlike the CNS, the PNS is not protected by the skull or by the spine, or even by the “blood-brain barrier” and is very susceptible to exposure to toxins and other injuries.  The PNS is divided into 2 main structures, the somatic nervous system and the autonomic nervous system.

The Somatic Nervous System

Otherwise known as the voluntary nervous system, and is associated with the skeletal and muscular control of the body.  It consists of afferent nerves (relay information from the body to the CNS) and efferent nerves (relay information from the CNS to the body). There are 2 parts of the somatic nervous system: 1) spinal nerves carry information out of the spinal cord and 2) cranial nerves carry information in and out of the brain.

The Autonomic Nervous System

The Primary function of the Autonomic Nervous system is to maintain homeostasis, and control internal organs and involuntary body functions (breathing, digestion, arousal).  there are 2 systems that make up the autonomic nervous system:

The Sympathetic Nervous System: Also known as the “fight or flight” system, it mobilizes the body in times of stress.  Hormones are released into the blood stream (most notably epinephrine and norepinephrine) which results in dilated pupils, increase heart rate, increase in sweat, and decrease digestion to name a few. This is a very fast acting system as a result of sending message and have a highly efficient neuron network to transmit messages.

The Parasympathetic Nervous System: Also known as the “rest and digest” system, it conserves energy and is engaged when a person is relaxed.  It is often accompanied by efficient digestion, sexual arousal, and increase autoimmune functioning (so having a parasympathetic system dominate over the sympathetic nervous system is typically considered healthier).  This is a slower acting system than the sympathetic nervous system, which is why it can seem to take longer to calm down from a stressful situation than it does to initially react.

The Central Nervous System

nervous systemThis system is responsible for coordinating the entire body’s functioning.  It is divided into 2 systems, the spinal cord and the brain.  The spinal cord is divided into 4 parts: the neck (cervical C1-C7), chest (thoracic T1-T12), back (lumbar L1-L5), tail bone (sacral S1).  Damage to any of these regions can result in paralysis, Quadrapalegia damages C1-C5 and parapalegia C6 and below.  The brain is the computer or headquarters for the whole body, both voluntary and involuntary behavior and can be divided into 3 major components (cerebrum, cerebellum, and brain stem) which will be described in depth.

The Cerebrum

This is the largest portion of the brain, and it is what controls perception, thought, and action.  It is also made up of multiple, which can be divided into the outer cerebral cortex and the inner subcortical structures.

Cerebral Cortex: The surface is made up of many folds (gyri) which can increase the surface level of the brain without increasing the size of the brain, and is made up of primarily grey matter.

There are 2 hemispheres: The Left Hemisphere primarily controls language and logical thought, the Right Hemisphere primarily controls perception, intuition, and comprehension.  Typically one hemisphere is dominant over the other, in left handed people the right hemisphere and in right handed people the left hemisphere.  The effects of brain damage can be significantly different in terms of behavior depending on the hemisphere the damage occured.

There are also 3 lobes: 1) The Frontal Lobe is the top frontal portion of the brain and is what makes us individuals as it controls personality, emotions, judgement, abstract thinking, and higher mental functioning. 2) The Parietal Lobe is located just behind the frontal lobe and is primarily responsible for sensory processing such as texture, pain, spatial awareness, motor movement, and linguistic skills. 3) The Temporal Lobe is  on the outside of the cortex by the temple, and is primarily responsible for the auditory cortex and limbic system and control emotions and memory.

Corpus Callosum: This is the term used to label the nerve fibers that connect the left and right hemisphere.  It is important because the right hemisphere controls the left side of the body (and vice versa) and what ever is sensed on the left side of the body is processed by the right hemisphere (and vice versa).  This becomes especially important to understand if you are ever working with an individual with a damaged corpus callosum known as “split brain,” and is sometimes severed purposefully to manage epileptic seizures. For example, language is processed in the left hemisphere of the brain, therefore words seen by the left eye would go to the opposite side (the right) and would not be able to be processed.  But words seen by the right eye would go to the left side of the brain and could be processed just fine.

The Limbic System: The study of the limbic system originated in the 1940’s and there has been some push back by more recent scientists calling our understanding of the limbic system as outdated and over simplified.  It’s primary role is to keep up alive and has 5 major components:

  • Thalamus: Also known as the “sensory relay limbic system
    center” it helps receive and process sensory information (except smell) and send it to the appropriate cortical areas.  It is also vital in the perception of pain, and schizophrenia has been linked to an abnormal thalamus.
  • Hypothalamus: It’s main role is homeostasis and is connected to the endocrine system through the autonomic nervous system.  This system is vital for hunger, sex, temperature regulation, sleep and more.
  • Hippocampus: The primary role is for the processing and storage of conscious memory.
  • Amygdala: Primarily controls the fear response, and basically works by attaching emotion to sensory experiences.  If stimulated aggression will increase as a response, and if removed aggression is eliminated (Kluver-Buey Syndrome).  It is also linked to PTSD as it attaches the fear response to memories.
  • Septum: Decreases aggression, and if damaged can result in “septal rage syndrome”

The Basal Ganglia: Controls body movement and posture and is made up of the caudate nucleau, putamen, substantia nigra, globus pallidus, and subthalamic nucleaus.  It doesn’t cause movement, rather its effects are inhibitory and when voluntarily moving the basal ganglia basically releases the brakes.  If damaged or not functioning properly it can result in Tourette’s syndrome, OCD, and Huntington’s disease (degenerating caudate nucleus and putamen), and Parkinson’s disease (loss of dopaminergic neurons in the substantia nigra).

The Cerebellum

Located at the base of the brain, it is the complimentary component to the Basl Ganglia.  This portion of the brain is responsible for smooth and coordinated movement, and acts automatically to adjust posture and muscle tension for balance.  Samage to the cerebellum could result in ataxia, which is noticeable lack of coordination and weakeness.  there is often times difficulties with gait, timing, posture, and vertigo.

The Brain Stem

Located below the subcortical regions of the cerebrum, and the most primitive part of the brain. The majority of the cranial nerves begin in the brain stem, and it is made uo of 3 primary components: The pons, medulla, and reticular formation.  The pons and medulla (with the pons sitting on top of the medulla) are vital in sleep and the REM sleep cycles and breathing.  The reticular formation is responsible for awareness and attention, as well as the  sleep-wake cycle and filtering incoming sensory information.

***The nervous system has a lot of components and parts, and understanding how they all work together is the secret to actually remembering the information. If you are struggling to understand something or need clarification please ask any questions in the comments below. It would also be great if you could share any tips or tricks you use to keep everything straight or to help you understand, or any practice exam questions you have come across specific to the Nervous System. 

You may find the information on this site is not enough to help you feel confident about your ability to pass the exam, That is OK and only you can be the judge of what you need. If this information seems overwhelming to you it does NOT mean you will fail the exam, but you may require a little more in depth material than is offered here. That is why there is a Product Reviews page which will give you a variety of additional options, as well as practice exam questions which I highly recommend as explained on the Study Tips page.

2 thoughts on “The Nervous System

  1. Hey Joy,
    This brings back so many memories, its been so long since I’ve studied about the nervous system, I used to be the top of my class 😀

    I totally forgot about the parasympathetic nervous system though, how long does it take to cool down as compared to the sympathetic nervous system though?

    1. The time for the parasympathetic nervous system really depends on each individual person. Lots of things play into this, someone who lives a healthy lifestyle with daily exercise, proper nutrition, sleeps well, and has good self care will be able to engage the parasympathetic nervous system quicker. This is also why deep breathing exercises are so effective for managing anxiety. I don’t believe you will be asked a specific amount of time that it takes to engage the parasympathetic nervous system in comparison to the sympathetic nervous system on the EPPP, but anyone is welcome to correct me if I’m wrong.

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