Saylor URL: http://www.saylor.org/books Saylor.org
and categorize male faces during the more fertile phases of their menstrual cycles. Although
researchers did not directly measure the presence of hormones, it is likely that phase-specific
hormonal differences influenced the women’s perceptions.
At this point you can begin to see the important role the hormones play in behavior. But the
hormones we have reviewed in this section represent only a subset of the many influences that
hormones have on our behaviors. In the chapters to come we will consider the important roles
that hormones play in many other behaviors, including sleeping, sexual activity, and helping and
harming others.
KEY TAKEAWAYS
- The body uses both electrical and chemical systems to create homeostasis.
- The CNS is made up of bundles of nerves that carry messages to and from the PNS
- The peripheral nervous system is composed of the autonomic nervous system (ANS) and the peripheral nervous
system (PNS). The ANS is further divided into the sympathetic (activating) and parasympathetic (calming) nervous
systems. These divisions are activated by glands and organs in the endocrine system. - Specific nerves, including sensory neurons, motor neurons, and interneurons, each have specific functions.
- The spinal cord may bypass the brain by responding rapidly using reflexes.
- The pituitary gland is a master gland, affecting many other glands.
- Hormones produced by the pituitary and adrenal glands regulate growth, stress, sexual functions, and chemical
balance in the body. - The adrenal glands produce epinephrine and norepinephrine, the hormones responsible for our reactions to stress.
- The sex hormones, testosterone, estrogen, and progesterone, play an important role in sex differences.
EXERCISES AND CRITICAL THINKING
- Recall a time when you were threatened or stressed. What physiological reactions did you experience in the situation,
and what aspects of the endocrine system do you think created those reactions? - Consider the emotions that you have experienced over the past several weeks. What hormones do you think might
have been involved in creating those emotions?
[1] Dabbs, J. M., Jr., Hargrove, M. F., & Heusel, C. (1996). Testosterone differences among college fraternities: Well-behaved vs.
rambunctious. Personality and Individual Differences, 20(2), 157–161.