The Biological Perspective 63Distant Connections: The Endocrine Glands
How do the glands fit into all of this? Aren’t there more
glands than just the adrenal glands? How do they affect our
behavior?Earlier we addressed neurons and the neurotransmitters and how they release into the
synapse to communicate with postsynaptic neurons. This type of chemical communica-
tion is fairly specific, primarily affecting neurons in the immediate vicinity of the origi-
nating neuron, and also very fast (almost immediate). Other structures also use chemical
communication but do so at a different rate and act in a more far-reaching manner. For
example, glands are organs in the body that secrete chemicals. Some glands, such as
salivary glands and sweat glands, secrete their chemicals directly onto the body’s tis-
sues through tiny tubes, or ducts. This kind of gland affects the functioning of the body
but doesn’t really affect behavior. Other glands, called endocrine glands, have no ducts
and secrete their chemicals directly into the bloodstream (see Figure 2. 9 ). The chem-
icals secreted by this type of gland are called hormones. As mentioned earlier in the
chapter when talking about the sympathetic division of the autonomic nervous system,
these hormones flow into the bloodstream, which carries them to their target organs.
The molecules of these hormones then fit into receptor sites on those organs to fulfill
their function, affecting behavior as they do so. As compared to synaptic communica-
tion, endocrine communication is generally slower due to the time it takes hormones to
travel to target organs, and the behaviors and responses they affect may not occur until
hours, weeks, or years later.
The hormones affect behavior and emotions by stimulating muscles, organs, or
other glands of the body. Some theories of emotion state that the surge in certain hor-
mones actually triggers the emotional reaction (Izard, 1988; Zajonc, 1980, 1984).
to Learning Objective 9.9. Some of the hormones produced by endocrine glands also
influence the activity of the brain, producing excitatory or inhibitory effects (Schwartz &
Javitch, 2013).
Practice Quiz How much do you remember?
Pick the best answer.
- If you touch a hot stove, your spinal cord can prompt you to with-
draw your hand without having to send the message all the way to
the brain. This is due to what scientists call
a. the reflex arc.
b. neuroplasticity.
c. the parasympathetic nervous system.
d. the sympathetic nervous system. - What is the process whereby the structure and function of brain
cells change in response to trauma, damage, or even learning?
a. shallow lesioning c. cell regeneration
b. deep lesioning d. neuroplasticity - The neurons of the sensory pathway contain
a. efferent neurons. c. both efferent and afferent neurons.
b. afferent neurons. d. voluntary muscle fibers.
4. Yvonne’s ability to reach for and pick up her book is largely due
to the functions of the pathway of the ____
nervous system.
a. sensory; somatic
b. motor; somatic
c. autonomic; peripheral
d. parasympathetic; autonomic
5. Which of the following would be active if you have just had an auto-
mobile accident?
a. sympathetic division
b. parasympathetic division
c. somatic division
d. motor division
endocrine glands
glands that secrete chemicals
called hormones directly into
the Dloodstream.hormones
chemicals released into the blood-
stream by endocrine glands.