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Psychology

<OpenstaxParagraph>
	Taste (gustation) and <OpenstaxTerm>smell</OpenstaxTerm> (olfaction) are called chemical senses because both have sensory receptors that respond to molecules in the food we eat or in the air we breathe. There is a pronounced interaction between our chemical senses. For example, when we describe the flavor of a given food, we are really referring to both gustatory and olfactory properties of the food working in combination.
</OpenstaxParagraph>
<OpenstaxH3>Taste (Gustation)</OpenstaxH3>
<OpenstaxParagraph>
	You have learned since elementary school that there are four basic groupings of taste: sweet, salty, sour, and bitter. Research demonstrates, however, that we have at least six <OpenstaxTerm>taste</OpenstaxTerm> groupings. Umami is our fifth taste. <OpenstaxTerm>Umami</OpenstaxTerm> is actually a Japanese word that roughly translates to yummy, and it is associated with a taste for monosodium glutamate (Kinnamon &amp; Vandenbeuch, 2009). There is also a growing body of experimental evidence suggesting that we possess a taste for the fatty content of a given food (Mizushige, Inoue, &amp; Fushiki, 2007).
</OpenstaxParagraph>
<OpenstaxParagraph>
	Molecules from the food and beverages we consume dissolve in our saliva and interact with taste receptors on our tongue and in our mouth and throat. <OpenstaxTerm>Taste buds</OpenstaxTerm> are formed by groupings of taste receptor cells with hair-like extensions that protrude into the central pore of the taste bud (<a href="#Figure_05_05_TasteBud">Figure 5.21</a>). Taste buds have a life cycle of ten days to two weeks, so even destroying some by burning your tongue won’t have any long-term effect; they just grow right back. Taste molecules bind to receptors on this extension and cause chemical changes within the sensory cell that result in neural impulses being transmitted to the brain via different nerves, depending on where the receptor is located. Taste information is transmitted to the medulla, thalamus, and limbic system, and to the gustatory cortex, which is tucked underneath the overlap between the frontal and temporal lobes (Maffei, Haley, &amp; Fontanini, 2012; Roper, 2013).
</OpenstaxParagraph>
<OpenstaxFigure id="Figure_05_05_TasteBud" src="https://openstax.org/apps/archive/20240226.174525/resources/d179531c540223b77ec227156c0d55b2cacc8760" alt="Illustration A shows a taste bud in an opening of the tongue, with the “tongue surface,” “taste pore,” “taste receptor cell” and “nerves” labeled. Part B is a micrograph showing taste buds on a human tongue." mediaType="image/jpg" width="731" height="383" />
<OpenstaxFigureText width="731">
	<strong>Figure 5.21</strong> (a) Taste buds are composed of a number of individual taste receptors cells that transmit information to nerves. (b) This micrograph shows a close-up view of the tongue’s surface. (credit a: modification of work by Jonas Töle; credit b: scale-bar data from Matt Russell)
</OpenstaxFigureText>
<OpenstaxH3>Smell (Olfaction)</OpenstaxH3>
<OpenstaxParagraph>
	<OpenstaxTerm>Olfactory receptor</OpenstaxTerm> cells are located in a mucous membrane at the top of the nose. Small hair-like extensions from these receptors serve as the sites for odor molecules dissolved in the mucus to interact with chemical receptors located on these extensions (<a href="#Figure_05_05_OlfacRecep">Figure 5.22</a>). Once an odor molecule has bound a given receptor, chemical changes within the cell result in signals being sent to the <OpenstaxTerm>olfactory bulb</OpenstaxTerm>: a bulb-like structure at the tip of the frontal lobe where the olfactory nerves begin. From the olfactory bulb, information is sent to regions of the limbic system and to the primary olfactory cortex, which is located very near the gustatory cortex (Lodovichi &amp; Belluscio, 2012; Spors et al., 2013).
</OpenstaxParagraph>
<OpenstaxFigure id="Figure_05_05_OlfacRecep" src="https://openstax.org/apps/archive/20240226.174525/resources/feb1f7070c1823a38a82c4fdff2c47bd14255faa" alt="An illustration shows a side view of a human head and the location of the “nasal cavity,” “olfactory receptors,” and “olfactory bulb.”" mediaType="image/jpg" width="650" height="417" />
<OpenstaxFigureText width="650">
	<strong>Figure 5.22</strong> Olfactory receptors are the hair-like parts that extend from the olfactory bulb into the mucous membrane of the nasal cavity.
</OpenstaxFigureText>
<OpenstaxParagraph>
	There is tremendous variation in the sensitivity of the olfactory systems of different species. We often think of dogs as having far superior olfactory systems than our own, and indeed, dogs can do some remarkable things with their noses. There is some evidence to suggest that dogs can “smell” dangerous drops in blood glucose levels as well as cancerous tumors (Wells, 2010). Dogs’ extraordinary olfactory abilities may be due to the increased number of functional genes for olfactory receptors (between 800 and 1200), compared to the fewer than 400 observed in humans and other primates (Niimura &amp; Nei, 2007).
</OpenstaxParagraph>
<OpenstaxParagraph>
	Many species respond to chemical messages, known as <OpenstaxTerm>pheromones</OpenstaxTerm>, sent by another individual (Wysocki &amp; Preti, 2004). Pheromonal communication often involves providing information about the reproductive status of a potential mate. So, for example, when a female rat is ready to mate, it secretes pheromonal signals that draw attention from nearby male rats. Pheromonal activation is actually an important component in eliciting sexual behavior in the male rat (Furlow, 1996, 2012; Purvis &amp; Haynes, 1972; Sachs, 1997). There has also been a good deal of research (and controversy) about pheromones in humans (Comfort, 1971; Russell, 1976; Wolfgang-Kimball, 1992; Weller, 1998).
</OpenstaxParagraph>

5.5.1 The Chemical Senses

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

3.3.1 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

Question	Answer
bulb-like structure at the tip of the frontal lobe, where the olfactory nerves begin	olfactory bulb
sensory cell for the olfactory system	olfactory receptor
taste for monosodium glutamate	umami