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Psychology

<OpenstaxParagraph>
	<OpenstaxTerm>Neurons</OpenstaxTerm> are the central building blocks of the nervous system, 100 billion strong at birth. Like all cells, neurons consist of several different parts, each serving a specialized function (<a href="#CNX_Psych_03_02_Neuron">Figure 3.8</a>). A neuron’s outer surface is made up of a <OpenstaxTerm>semipermeable membrane</OpenstaxTerm>. This membrane allows smaller molecules and molecules without an electrical charge to pass through it, while stopping larger or highly charged molecules.
</OpenstaxParagraph>
<OpenstaxFigure id="CNX_Psych_03_02_Neuron" src="https://openstax.org/apps/archive/20240226.174525/resources/8ef5efcb722f347fa1a7f333ed74760cfaf0a055" alt="An illustration shows a neuron with labeled parts for the cell membrane, dendrite, cell body, axon, and terminal buttons. A myelin sheath covers part of the neuron." mediaType="image/jpeg" width="487" height="344" />
<OpenstaxFigureText width="487">
	<strong>Figure 3.8</strong> This illustration shows a prototypical neuron, which is being myelinated by a glial cell.
</OpenstaxFigureText>
<OpenstaxParagraph>
	The nucleus of the neuron is located in the <OpenstaxTerm>soma</OpenstaxTerm>, or cell body. The soma has branching extensions known as <OpenstaxTerm>dendrites</OpenstaxTerm>. The neuron is a small information processor, and dendrites serve as input sites where signals are received from other neurons. These signals are transmitted electrically across the soma and down a major extension from the soma known as the <OpenstaxTerm>axon</OpenstaxTerm>, which ends at multiple <OpenstaxTerm>terminal buttons</OpenstaxTerm>. The terminal buttons contain <OpenstaxTerm>synaptic vesicles</OpenstaxTerm> that house <OpenstaxTerm>neurotransmitters</OpenstaxTerm>, the chemical messengers of the nervous system. 
</OpenstaxParagraph>
<OpenstaxParagraph>
	Axons range in length from a fraction of an inch to several feet. In some axons, glial cells form a fatty substance known as the <OpenstaxTerm>myelin sheath</OpenstaxTerm>, which coats the axon and acts as an insulator, increasing the speed at which the signal travels. The myelin sheath is not continuous and there are small gaps that occur down the length of the axon. These gaps in the myelin sheath are known as the <OpenstaxTerm>Nodes of Ranvier</OpenstaxTerm>. The myelin sheath is crucial for the normal operation of the neurons within the nervous system: the loss of the insulation it provides can be detrimental to normal function. To understand how this works, let’s consider an example. PKU, a genetic disorder discussed earlier, causes a reduction in myelin and abnormalities in white matter cortical and subcortical structures. The disorder is associated with a variety of issues including severe cognitive deficits, exaggerated reflexes, and seizures (Anderson &amp; Leuzzi, 2010; Huttenlocher, 2000). Another disorder, multiple sclerosis (MS), an autoimmune disorder, involves a large-scale loss of the myelin sheath on axons throughout the nervous system. The resulting interference in the electrical signal prevents the quick transmittal of information by neurons and can lead to a number of symptoms, such as dizziness, fatigue, loss of motor control, and sexual dysfunction. While some treatments may help to modify the course of the disease and manage certain symptoms, there is currently no known cure for multiple sclerosis.
</OpenstaxParagraph>
<OpenstaxParagraph>
	In healthy individuals, the neuronal signal moves rapidly down the axon to the terminal buttons, where synaptic vesicles release neurotransmitters into the synaptic cleft (<a href="#CNX_Psych_03_02_Synapse">Figure 3.9</a>). The <OpenstaxTerm>synaptic cleft</OpenstaxTerm> is a very small space between two neurons and is an important site where communication between neurons occurs. Once neurotransmitters are released into the synaptic cleft, they travel across it and bind with corresponding receptors on the dendrite of an adjacent neuron. <OpenstaxTerm>Receptors</OpenstaxTerm>, proteins on the cell surface where neurotransmitters attach, vary in shape, with different shapes “matching” different neurotransmitters.
</OpenstaxParagraph>
<OpenstaxParagraph>
	How does a neurotransmitter “know” which receptor to bind to? The neurotransmitter and the receptor have what is referred to as a lock-and-key relationship—specific neurotransmitters fit specific receptors similar to how a key fits a lock. The neurotransmitter binds to any receptor that it fits.
</OpenstaxParagraph>
<OpenstaxFigure id="CNX_Psych_03_02_Synapse" src="https://openstax.org/apps/archive/20240226.174525/resources/19b96297b4eb951260d2140515a3e7261f82d331" alt="Image (a) shows the synaptic space between two neurons, with neurotransmitters being released into the synapse and attaching to receptors. Image (b) is a micrograph showing a spherical terminal button with part of the exterior removed, revealing a solid interior of small round parts." mediaType="image/jpg" width="976" height="428" />
<OpenstaxFigureText width="976">
	<strong>Figure 3.9</strong> (a) The synaptic cleft is the space between the terminal button of one neuron and the dendrite of another neuron. (b) In this pseudo-colored image from a scanning electron microscope, a terminal button (green) has been opened to reveal the synaptic vesicles (orange and blue) inside. Each vesicle contains about 10,000 neurotransmitter molecules. (credit b: modification of work by Tina Carvalho, NIH-NIGMS; scale-bar data from Matt Russell)
</OpenstaxFigureText>

3.2.1 Neuron Structure

1 Introduction to Psychology

1.1 What Is Psychology?

1.1.1 Why Study Psychology?

1.2 History of Psychology

1.2.1 Wundt and Structuralism

1.2.2 Functionalism

1.2.3 Freud and Psychoanalytic Theory

1.2.4 Wertheimer, Koffka, Köhler, and Gestalt Psychology

1.2.5 Pavlov, Watson, Skinner, and Behaviorism

1.2.6 Maslow, Rogers, and Humanism

1.2.7 The Cognitive Revolution

1.2.8 Multicultural And Cross-Cultural Psychology

1.2.9 Women in Psychology

1.3 Contemporary Psychology

1.3.1 Biopsychology and Evolutionary Psychology

1.3.2 Sensation and Perception

1.3.3 Cognitive Psychology

1.3.4 Developmental Psychology

1.3.5 Personality Psychology

1.3.6 Social Psychology

1.3.7 Industrial-Organizational Psychology

1.3.8 Health Psychology

1.3.9 Sport and Exercise Psychology

1.3.10 Clinical Psychology

1.3.11 Forensic Psychology

1.4 Careers in Psychology

1.4.1 Other Careers in Academic Settings

1.4.2 Career Options Outside of Academic Settings

2 Psychological Research

2.1 Why Is Research Important?

2.1.1 Use of Research Information

2.1.2 NOTABLE RESEARCHERS

2.1.3 The Process of Scientific Research

2.2 Approaches to Research

2.2.1 Clinical or Case Studies

2.2.2 Naturalistic Observation

2.2.3 Surveys

2.2.4 Archival Research

2.2.5 Longitudinal and Cross-Sectional Research

2.3 Analyzing Findings

2.3.1 Correlational Research

2.3.2 Causality: Conducting Experiments and Using the Data

2.3.3 Reliability and Validity

2.4 Ethics

2.4.1 Research Involving Human Participants

2.4.2 Research Involving Animal Subjects

3 Biopsychology

3.1 Human Genetics

3.1.1 Genetic Variation

3.1.2 Gene-Environment Interactions

3.2 Cells of the Nervous System

3.2.2 Neuronal Communication

3.2.3 Neurotransmitters and Drugs

3.3 Parts of the Nervous System

3.3.1 Peripheral Nervous System

3.4 The Brain and Spinal Cord

3.4.1 The Spinal Cord

3.4.2 The Two Hemispheres

3.4.3 Forebrain Structures

3.4.4 Midbrain and Hindbrain Structures

3.4.5 Brain Imaging

3.5 The Endocrine System

3.5.1 Major Glands

4 States of Consciousness

4.1 What Is Consciousness?

4.1.1 Biological Rhythms

4.1.2 Problems With Circadian Rhythms

4.2 Sleep and Why We Sleep

4.2.1 What is Sleep?

4.2.2 Why Do We Sleep?

4.3 Stages of Sleep

4.3.1 NREM Stages of Sleep

4.3.2 REM Sleep

4.4 Sleep Problems and Disorders

4.4.1 Insomnia

4.4.2 Parasomnias

4.4.3 Sleep Apnea

4.4.4 Narcolepsy

4.5 Substance Use and Abuse

4.5.1 Substance Use Disorders

4.5.2 Drug Categories

4.6 Other States of Consciousness

4.6.1 Hypnosis

4.6.2 Meditation

5 Sensation and Perception

5.1 Sensation versus Perception

5.1.1 Sensation

5.1.2 Perception

5.2 Waves and Wavelengths

5.2.1 Amplitude and Wavelength

5.2.2 Light Waves

5.2.3 Sound Waves

5.3 Vision

5.3.1 Anatomy of the Visual System

5.3.2 Color and Depth Perception

5.4 Hearing

5.4.1 Anatomy of the Auditory System

5.4.2 Pitch Perception

5.4.3 Sound Localization

Question	Answer
major extension of the soma	axon
fatty substance that insulates axons	myelin sheath
open spaces that are found in the myelin sheath that encases the axon	Nodes of Ranvier
cell membrane that allows smaller molecules or molecules without an electrical charge to pass through it, while stopping larger or highly charged molecules	semipermeable membrane
cell body	soma
small gap between two neurons where communication occurs	synaptic cleft