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Psychology

<OpenstaxParagraph>
	The peripheral nervous system is made up of thick bundles of axons, called nerves, carrying messages back and forth between the CNS and the muscles, organs, and senses in the periphery of the body (i.e., everything outside the CNS). The PNS has two major subdivisions: the somatic nervous system and the autonomic nervous system.
</OpenstaxParagraph>
<OpenstaxParagraph>
	The <OpenstaxTerm>somatic nervous system</OpenstaxTerm> is associated with activities traditionally thought of as conscious or voluntary. It is involved in the relay of sensory and motor information to and from the CNS; therefore, it consists of motor neurons and sensory neurons. Motor neurons, carrying instructions from the CNS to the muscles, are efferent fibers (efferent means “moving away from”). Sensory neurons, carrying sensory information to the CNS, are afferent fibers (afferent means “moving toward”). A helpful way to remember this is that efferent = exit and afferent = arrive. Each nerve is basically a bundle of neurons forming a two-way superhighway, containing thousands of axons, both efferent and afferent.
</OpenstaxParagraph>
<OpenstaxParagraph>
	The <OpenstaxTerm>autonomic nervous system</OpenstaxTerm> controls our internal organs and glands and is generally considered to be outside the realm of voluntary control. It can be further subdivided into the sympathetic and parasympathetic divisions (<a href="#CNX_Psych_03_03_Autonomic">Figure 3.14</a>). The <OpenstaxTerm>sympathetic nervous system</OpenstaxTerm> is involved in preparing the body for stress-related activities; the <OpenstaxTerm>parasympathetic nervous system</OpenstaxTerm> is associated with returning the body to routine, day-to-day operations. The two systems have complementary functions, operating in tandem to maintain the body’s homeostasis. <OpenstaxTerm>Homeostasis</OpenstaxTerm> is a state of equilibrium, or balance, in which biological conditions (such as body temperature) are maintained at optimal levels.
</OpenstaxParagraph>
<OpenstaxFigure id="CNX_Psych_03_03_Autonomic" src="https://openstax.org/apps/archive/20240226.174525/resources/b561c8c913a538c0b36aec494521aa27287a785b" alt="A diagram of a human body lists the different functions of the sympathetic and parasympathetic nervous system. The parasympathetic system can constrict pupils, stimulate salivation, slow heart rate, constrict bronchi, stimulate digestion, stimulate bile secretion, and cause the bladder to contract. The sympathetic nervous system can dilate pupils, inhibit salivation, increase heart rate, dilate bronchi, inhibit digestion, stimulate the breakdown of glycogen, stimulate secretion of adrenaline and noradrenaline, and inhibit contraction of the bladder." mediaType="image/jpg" width="650" height="676" />
<OpenstaxFigureText width="650">
	Figure 3.14 The sympathetic and parasympathetic divisions of the autonomic nervous system have the opposite effects on various systems.
</OpenstaxFigureText>
<OpenstaxParagraph>
	The sympathetic nervous system is activated when we are faced with stressful or high-arousal situations. The activity of this system was adaptive for our ancestors, increasing their chances of survival. Imagine, for example, that one of our early ancestors, out hunting small game, suddenly disturbs a large bear with her cubs. At that moment, the hunter's body undergoes a series of changes—a direct function of sympathetic activation—preparing them to face the threat. The pupils dilate, the heart rate and blood pressure increase, the bladder relaxes, and the liver releases glucose; adrenaline surges into the bloodstream. This constellation of physiological changes, known as the <OpenstaxTerm>fight or flight response</OpenstaxTerm>, allows the body access to energy reserves and heightened sensory capacity so that it might fight off a threat or run away to safety.
</OpenstaxParagraph>
<OpenstaxNote>
	<OpenstaxNoteTitle> Link to Learning </OpenstaxNoteTitle> 
	<OpenstaxParagraph>
		Watch this <a href="http://openstax.org/l/response">video about the Fight Flight Freeze response</a> to learn more.
	</OpenstaxParagraph>
</OpenstaxNote>
<OpenstaxParagraph>
	While it is clear that such a response would be critical for survival for our ancestors, who lived in a world full of real physical threats, many of the high-arousal situations we face in the modern world are more psychological in nature. For example, think about how you feel when you have to stand up and give a presentation in front of a roomful of people, or right before taking a big test. You are in no real physical danger in those situations, and yet you have evolved to respond to a perceived threat with the <OpenstaxTerm>fight or flight</OpenstaxTerm> response. This kind of response is not nearly as adaptive in the modern world; in fact, we suffer negative health consequences when faced constantly with psychological threats that we can neither fight nor flee. Recent research suggests that an increase in susceptibility to heart disease (Chandola, Brunner, &amp; Marmot, 2006) and impaired function of the immune system (Glaser &amp; Kiecolt-Glaser, 2005) are among the many negative consequences of persistent and repeated exposure to stressful situations. Some of this tendency for stress reactivity can be wired by early experiences of trauma.
</OpenstaxParagraph>
<OpenstaxParagraph>
	Once the threat has been resolved, the parasympathetic nervous system takes over and returns bodily functions to a relaxed state. Our hunter’s heart rate and blood pressure return to normal, the pupils constrict, bladder control is restored, and the liver begins to store glucose in the form of glycogen for future use. These restorative processes are associated with activation of the parasympathetic nervous system.
</OpenstaxParagraph>

3.3.1 Peripheral Nervous System

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

3.2.1 Neuron Structure

3.2.2 Neuronal Communication

3.2.3 Neurotransmitters and Drugs

3.3 Parts of the 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
controls our internal organs and glands	autonomic nervous system
activation of the sympathetic division of the autonomic nervous system, allowing access to energy reserves and heightened sensory capacity so that we might fight off a given threat or run away to safety	fight or flight response
state of equilibrium—biological conditions, such as body temperature, are maintained at optimal levels	homeostasis
associated with routine, day-to-day operations of the body	parasympathetic nervous system
relays sensory and motor information to and from the CNS	somatic nervous system
involved in stress-related activities and functions	sympathetic nervous system