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Psychology 2e

3.5 The Endocrine System

Psychology 2e3.5 The Endocrine System
  1. Preface
  2. 1 Introduction to Psychology
    1. Introduction
    2. 1.1 What Is Psychology?
    3. 1.2 History of Psychology
    4. 1.3 Contemporary Psychology
    5. 1.4 Careers in Psychology
    6. Key Terms
    7. Summary
    8. Review Questions
    9. Critical Thinking Questions
    10. Personal Application Questions
  3. 2 Psychological Research
    1. Introduction
    2. 2.1 Why Is Research Important?
    3. 2.2 Approaches to Research
    4. 2.3 Analyzing Findings
    5. 2.4 Ethics
    6. Key Terms
    7. Summary
    8. Review Questions
    9. Critical Thinking Questions
    10. Personal Application Questions
  4. 3 Biopsychology
    1. Introduction
    2. 3.1 Human Genetics
    3. 3.2 Cells of the Nervous System
    4. 3.3 Parts of the Nervous System
    5. 3.4 The Brain and Spinal Cord
    6. 3.5 The Endocrine System
    7. Key Terms
    8. Summary
    9. Review Questions
    10. Critical Thinking Questions
    11. Personal Application Questions
  5. 4 States of Consciousness
    1. Introduction
    2. 4.1 What Is Consciousness?
    3. 4.2 Sleep and Why We Sleep
    4. 4.3 Stages of Sleep
    5. 4.4 Sleep Problems and Disorders
    6. 4.5 Substance Use and Abuse
    7. 4.6 Other States of Consciousness
    8. Key Terms
    9. Summary
    10. Review Questions
    11. Critical Thinking Questions
    12. Personal Application Questions
  6. 5 Sensation and Perception
    1. Introduction
    2. 5.1 Sensation versus Perception
    3. 5.2 Waves and Wavelengths
    4. 5.3 Vision
    5. 5.4 Hearing
    6. 5.5 The Other Senses
    7. 5.6 Gestalt Principles of Perception
    8. Key Terms
    9. Summary
    10. Review Questions
    11. Critical Thinking Questions
    12. Personal Application Questions
  7. 6 Learning
    1. Introduction
    2. 6.1 What Is Learning?
    3. 6.2 Classical Conditioning
    4. 6.3 Operant Conditioning
    5. 6.4 Observational Learning (Modeling)
    6. Key Terms
    7. Summary
    8. Review Questions
    9. Critical Thinking Questions
    10. Personal Application Questions
  8. 7 Thinking and Intelligence
    1. Introduction
    2. 7.1 What Is Cognition?
    3. 7.2 Language
    4. 7.3 Problem Solving
    5. 7.4 What Are Intelligence and Creativity?
    6. 7.5 Measures of Intelligence
    7. 7.6 The Source of Intelligence
    8. Key Terms
    9. Summary
    10. Review Questions
    11. Critical Thinking Questions
    12. Personal Application Questions
  9. 8 Memory
    1. Introduction
    2. 8.1 How Memory Functions
    3. 8.2 Parts of the Brain Involved with Memory
    4. 8.3 Problems with Memory
    5. 8.4 Ways to Enhance Memory
    6. Key Terms
    7. Summary
    8. Review Questions
    9. Critical Thinking Questions
    10. Personal Application Questions
  10. 9 Lifespan Development
    1. Introduction
    2. 9.1 What Is Lifespan Development?
    3. 9.2 Lifespan Theories
    4. 9.3 Stages of Development
    5. 9.4 Death and Dying
    6. Key Terms
    7. Summary
    8. Review Questions
    9. Critical Thinking Questions
    10. Personal Application Questions
  11. 10 Emotion and Motivation
    1. Introduction
    2. 10.1 Motivation
    3. 10.2 Hunger and Eating
    4. 10.3 Sexual Behavior
    5. 10.4 Emotion
    6. Key Terms
    7. Summary
    8. Review Questions
    9. Critical Thinking Questions
    10. Personal Application Questions
  12. 11 Personality
    1. Introduction
    2. 11.1 What Is Personality?
    3. 11.2 Freud and the Psychodynamic Perspective
    4. 11.3 Neo-Freudians: Adler, Erikson, Jung, and Horney
    5. 11.4 Learning Approaches
    6. 11.5 Humanistic Approaches
    7. 11.6 Biological Approaches
    8. 11.7 Trait Theorists
    9. 11.8 Cultural Understandings of Personality
    10. 11.9 Personality Assessment
    11. Key Terms
    12. Summary
    13. Review Questions
    14. Critical Thinking Questions
    15. Personal Application Questions
  13. 12 Social Psychology
    1. Introduction
    2. 12.1 What Is Social Psychology?
    3. 12.2 Self-presentation
    4. 12.3 Attitudes and Persuasion
    5. 12.4 Conformity, Compliance, and Obedience
    6. 12.5 Prejudice and Discrimination
    7. 12.6 Aggression
    8. 12.7 Prosocial Behavior
    9. Key Terms
    10. Summary
    11. Review Questions
    12. Critical Thinking Questions
    13. Personal Application Questions
  14. 13 Industrial-Organizational Psychology
    1. Introduction
    2. 13.1 What Is Industrial and Organizational Psychology?
    3. 13.2 Industrial Psychology: Selecting and Evaluating Employees
    4. 13.3 Organizational Psychology: The Social Dimension of Work
    5. 13.4 Human Factors Psychology and Workplace Design
    6. Key Terms
    7. Summary
    8. Review Questions
    9. Critical Thinking Questions
    10. Personal Application Questions
  15. 14 Stress, Lifestyle, and Health
    1. Introduction
    2. 14.1 What Is Stress?
    3. 14.2 Stressors
    4. 14.3 Stress and Illness
    5. 14.4 Regulation of Stress
    6. 14.5 The Pursuit of Happiness
    7. Key Terms
    8. Summary
    9. Review Questions
    10. Critical Thinking Questions
    11. Personal Application Questions
  16. 15 Psychological Disorders
    1. Introduction
    2. 15.1 What Are Psychological Disorders?
    3. 15.2 Diagnosing and Classifying Psychological Disorders
    4. 15.3 Perspectives on Psychological Disorders
    5. 15.4 Anxiety Disorders
    6. 15.5 Obsessive-Compulsive and Related Disorders
    7. 15.6 Posttraumatic Stress Disorder
    8. 15.7 Mood Disorders
    9. 15.8 Schizophrenia
    10. 15.9 Dissociative Disorders
    11. 15.10 Disorders in Childhood
    12. 15.11 Personality Disorders
    13. Key Terms
    14. Summary
    15. Review Questions
    16. Critical Thinking Questions
    17. Personal Application Questions
  17. 16 Therapy and Treatment
    1. Introduction
    2. 16.1 Mental Health Treatment: Past and Present
    3. 16.2 Types of Treatment
    4. 16.3 Treatment Modalities
    5. 16.4 Substance-Related and Addictive Disorders: A Special Case
    6. 16.5 The Sociocultural Model and Therapy Utilization
    7. Key Terms
    8. Summary
    9. Review Questions
    10. Critical Thinking Questions
    11. Personal Application Questions
  18. References
  19. Index

Learning Objectives

By the end of this section, you will be able to:
  • Identify the major glands of the endocrine system
  • Identify the hormones secreted by each gland
  • Describe each hormone’s role in regulating bodily functions

The endocrine system consists of a series of glands that produce chemical substances known as hormones (Figure 3.30). Like neurotransmitters, hormones are chemical messengers that must bind to a receptor in order to send their signal. However, unlike neurotransmitters, which are released in close proximity to cells with their receptors, hormones are secreted into the bloodstream and travel throughout the body, affecting any cells that contain receptors for them. Thus, whereas neurotransmitters’ effects are localized, the effects of hormones are widespread. Also, hormones are slower to take effect, and tend to be longer lasting.

A diagram of the human body illustrates the locations of the thymus, several parts within the brain (pineal gland, thalamus, hypothalamus,  pituitary gland), several parts within the thyroid (cartilage of the larynx, thyroid gland, parathyroid glands, trachea), the adrenal glands, pancreas, uterus (female), ovaries (female), and testes (male).
Figure 3.30 The major glands of the endocrine system are shown.

Hormones are involved in regulating all sorts of bodily functions, and they are ultimately controlled through interactions between the hypothalamus (in the central nervous system) and the pituitary gland (in the endocrine system). Imbalances in hormones are related to a number of disorders. This section explores some of the major glands that make up the endocrine system and the hormones secreted by these glands (Table 3.2).

Major Glands

The pituitary gland descends from the hypothalamus at the base of the brain, and acts in close association with it. The pituitary is often referred to as the “master gland” because its messenger hormones control all the other glands in the endocrine system, although it mostly carries out instructions from the hypothalamus. In addition to messenger hormones, the pituitary also secretes growth hormone, endorphins for pain relief, and a number of key hormones that regulate fluid levels in the body.

Located in the neck, the thyroid gland releases hormones that regulate growth, metabolism, and appetite. In hyperthyroidism, or Grave’s disease, the thyroid secretes too much of the hormone thyroxine, causing agitation, bulging eyes, and weight loss. In hypothyroidism, reduced hormone levels cause sufferers to experience tiredness, and they often complain of feeling cold. Fortunately, thyroid disorders are often treatable with medications that help reestablish a balance in the hormones secreted by the thyroid.

The adrenal glands sit atop our kidneys and secrete hormones involved in the stress response, such as epinephrine (adrenaline) and norepinephrine (noradrenaline). The pancreas is an internal organ that secretes hormones that regulate blood sugar levels: insulin and glucagon. These pancreatic hormones are essential for maintaining stable levels of blood sugar throughout the day by lowering blood glucose levels (insulin) or raising them (glucagon). People who suffer from diabetes do not produce enough insulin; therefore, they must take medications that stimulate or replace insulin production, and they must closely control the amount of sugars and carbohydrates they consume.

The gonads secrete sexual hormones, which are important in reproduction, and mediate both sexual motivation and behavior. The female gonads are the ovaries; the male gonads are the testes. Ovaries secrete estrogens and progesterone, and the testes secrete androgens, such as testosterone.

Major Endocrine Glands and Associated Hormone Functions
Endocrine Gland Associated Hormones Function
Hypothalamus Releasing and inhibiting hormones, such as oxytocin Regulate hormone release from pituitary gland
Pituitary Growth hormone, releasing and inhibiting hormones (such as thyroid stimulating hormone) Regulate growth, regulate hormone release
Thyroid Thyroxine, triiodothyronine Regulate metabolism and appetite
Pineal Melatonin Regulate some biological rhythms such as sleep cycles
Adrenal Epinephrine, norepinephrine Stress response, increase metabolic activities
Pancreas Insulin, glucagon Regulate blood sugar levels
Ovaries Estrogen, progesterone Mediate sexual motivation and behavior, reproduction
Testes Androgens, such as testosterone Mediate sexual motivation and behavior, reproduction
Table 3.2

Dig Deeper

Athletes and Anabolic Steroids

Although it is against Federal laws and many professional athletic associations (The National Football League, for example) have banned their use, anabolic steroid drugs continue to be used by amateur and professional athletes. The drugs are believed to enhance athletic performance. Anabolic steroid drugs mimic the effects of the body’s own steroid hormones, like testosterone and its derivatives. These drugs have the potential to provide a competitive edge by increasing muscle mass, strength, and endurance, although not all users may experience these results. Moreover, use of performance-enhancing drugs (PEDs) does not come without risks. Anabolic steroid use has been linked with a wide variety of potentially negative outcomes, ranging in severity from largely cosmetic (acne) to life threatening (heart attack). Furthermore, use of these substances can result in profound changes in mood and can increase aggressive behavior (National Institute on Drug Abuse, 2001).

Baseball player Alex Rodriguez (A-Rod) spent the latter part of his playing career at the center of a media storm regarding his use of illegal PEDs. Rodriguez’s performance on the field was unparalleled while using the drugs; his success played a large role in negotiating a contract that made him the highest paid player in professional baseball. A subsequent scandal and suspension tarnished his reputation and, according to a statement he made once retired, cost him over $40 million. Even lower-profile athletes, particularly in cycling and Olympic sports, have been revealed as steroid users. What are your thoughts on athletes and doping? Why or why not should the use of PEDs be banned? What advice would you give an athlete who was considering using PEDs?

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