15 Hormones and Behavior
Original chapter from OpenStax Psychology 2e adapted by the Queen’s University Psychology Department
This Open Access chapter was originally written for OpenStax. Information on OpenStax can be found below.
We encourage students to use the “Three-Step Method” for support in their learning. Please find our version of the Three-Step Method, created in collaboration with Queen’s Student Academic Success Services, at the following link: https://sass.queensu.ca/psyc100/
The goal of this module is to introduce you to the topic of hormones and behavior. This field of study is also called behavioral endocrinology, which is the scientific study of the interaction between hormones and behavior. This interaction is bidirectional: hormones can influence behavior, and behavior can sometimes influence hormone concentrations. Hormones are chemical messengers released from endocrine glands that travel through the blood system to influence the nervous system to regulate behaviors such as aggression, mating, and parenting of individuals.
Learning Objectives
- Identify the major glands of the endocrine system
- Identify the hormones secreted by each gland
- Describe each hormone’s role in regulating bodily functions
Introduction
The endocrine system consists of a series of glands that produce chemical substances known as hormones (Figure 1). 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.
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 1).
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, the thyroid secretes too much of the hormone thyroxine, causing agitation, bulging eyes, and weight loss. One cause of hyperthyroidism is Graves’ disease, an autoimmune disease in which one’s own body attacks itself. 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 hormones related to sexuality, sex, reproduction, and other phenomena, including physical/bodily aspects and behaviour. The gonads are either in the ovaries (usually tied to femaleness, but not always) and testes (usually tied to maleness, but not always). All gonads secrete estrogens (e.g., estradiol), progesterone, and androgens (e.g., testosterone). The testes secrete more androgens than the ovaries do, on average; and the ovaries show more monthly cyclicity during reproductive age, in relation to menstrual cycles.
| Endocrine Gland | Associated Hormones | Function |
|---|---|---|
| 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/Testes | Estrogen, progesterone, androgens, such as testosterone | Mediate sexual motivation and behavior, reproduction |
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 excelled 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 should the use of PEDs be banned or not banned? What advice would you give an athlete who was considering using PEDs?
This is the end to our introduction of hormones. Please find some practice questions below!
Vocabulary
Adrenal glands
Sits atop our kidneys and secretes hormones involved in the stress response
Diabetes
Disease related to insufficient insulin production
Endocrine system
Series of glands that produce chemical substances known as hormones
Gonads
Secrete hormones related to sexuality, sex, reproduction, and other phenomena, including physical/bodily aspects and behaviour. The gonads are either in the ovaries (usually tied to femaleness, but not always) and testes (usually tied to maleness, but not always).
Hormones
Chemical messenger released by endocrine glands
Pancreas
Secretes hormones that regulate blood sugar
Pituitary gland
Secretes a number of key hormones, which regulate fluid levels in the body, and a number of messenger hormones, which direct the activity of other glands in the endocrine system
Thyroid gland
Secretes hormones that regulate growth, metabolism, and appetite
How to cite this Chapter using APA Style:
Spielman, R. M., Jenkins, W. J., Lovett, M. D (2020). The Endocrine System. In Psychology 2e. OpenStax; Houston, Texas. Adapted for use by Queen’s University. Original chapter can be retrieved from: https://openstax.org/books/psychology-2e/pages/3-5-the-endocrine-system
Copyright and Acknowledgment:
OpenStax can be accessed for free at https://openstax.org/books/psychology-2e/pages/1-introduction
This material is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this license, visit: https://creativecommons.org/licenses/by/4.0/deed.en
Series of glands that produce chemical substances known as hormones
Chemical messenger released by endocrine glands
Secretes a number of key hormones, which regulate fluid levels in the body, and a number of messenger hormones, which direct the activity of other glands in the endocrine system
Secretes hormones that regulate growth, metabolism, and appetite
Sits atop our kidneys and secretes hormones involved in the stress response
Secretes hormones that regulate blood sugar
Disease related to insufficient insulin production
Secrete hormones related to sexuality, sex, reproduction, and other phenomena, including physical/bodily aspects and behaviour. The gonads are either in the ovaries (usually tied to femaleness, but not always) and testes (usually tied to maleness, but not always).
