Summary An Introduction to Behavioral Endocrinology J Sixth Edition 2022 Randy J. Nelson 0197542751
Summary chapters 1 - 12
An Introduction to Behavioral Endocrinology, Sixth Edition 2022
by Randy J. Nelson (Author), Lance J. Kriegsfeld
-0197542750
+ 75 common exam questions and answers all chapters – answers separately
+ 67 important core concepts you must know alphabetically
+ important visuals included
,Summary An Introduction to Behavioral Endocrinology J Sixth Edition 2022 Randy J. Nelson 0197542751
,Summary An Introduction to Behavioral Endocrinology J Sixth Edition 2022 Randy J. Nelson 0197542751
, Summary An Introduction to Behavioral Endocrinology J Sixth Edition 2022 Randy J. Nelson 0197542751
Chapter 1 The Study of Behavioral Endocrinology
Red words are marked bold in the book.
Behavioral endocrinology is the scientific study of the interaction between hormones and
behavior and is bidirectional: hormones can affect behavior and behavior can influence
hormones.
Hormones are chemical messengers released from endocrine glands to influence the
nervous system in regulating physiology and behavior of an individual. Hormones do not
hijack the nervous system to influence behavior, they change the probability that a specific
behavior will occur within the appropriate behavioral or social context.
Historical Roots of Behavioral Endocrinology
Castration has historically been the most common manipulation of the endocrine system. For
millennia, the testes were removed in individuals of many species of domestic animals to
make them better to eat or easier to control, and the behavioral and physical effects of
castration have been known for ages. For centuries, royalty employed men castrated before
puberty, eunuchs, to guard women from other men.
Prepubertal castration in humans leads to a characteristic physical appearance marked by
short stature and long arms, sexual behaviors are unlikely to develop. Secondary male sex
characteristics (such as growing of body hair and lowering of the voice) are also affected by
prepubertal removal of the testes.
The first formal study of endocrinology, in the nineteenth century and performed by
Berthold, demonstrated that a substance produced by the testes could travel through the
bloodstream and eventually affect behavior. He demonstrated that a product of the testes
was necessary for a cockerel (immature male chicken) to develop into a normal adult
rooster. After dividing 6 cockerels into 3 pairs, he castrated all 6 cockerels and 1 pair didn’t
get additional treatment, 1 pair got 1 testis replaced in their abdomen and 1 pair got a testis
of the other cockerel replaced in the abdomen. The 2 that didn’t get additional treatment
didn’t show sexual behavior in adulthood, all 4 cockerels that had a testis replaced
developed normal sex behavior, the replaced testes were attached to the intestines and
created vascular supply. Based on this experiment Berthold drew three major conclusions:
1. The testes are transplantable organs
2. Transplanted testes can function and produce sperm
3. Because the testes functioned normally after all nerves were severed, there are no
specific nerves directing testicular function
After evaluating the results of his study, Berthold had two concepts at hand:
1. Various parts of the body release specific agents into blood
2. These agents travel through the bloodstream to particular target organs
What are Hormones?
Hormones: substances from many different glands affecting an increasing number and range
of behaviors. Hormones are released from these glands into the bloodstream where they
then may act on target organs or tissues at some distance from their origin.
Hormones coordinate the physiology and behavior of an animal by regulating, integrating and
controlling its bodily function. An example are several metabolic hormones which work
together to elevate blood glucose levels prior to awakening, in anticipation of increased
activity and energy demand. This “programmed” elevation of fuel availability coordinates the
animal’s physiology with its behavior.
Neurotransmitters are the chemicals used by the nervous system in coordinating animal’s
activities. Hormones function similarly to neurotransmitters, except that hormones can
, Summary An Introduction to Behavioral Endocrinology J Sixth Edition 2022 Randy J. Nelson 0197542751
operate over a much greater distance and temporal range.
Neural Transmission vs Hormonal Communication
Neural messages can travel only to destinations along existing nerve tracts. Hormonal
messages can travel anywhere in the body via the circulatory system, any cell receiving
blood is potentially able to receive a hormonal message. Neural messages are all-or-none
events that have rapid onset and offset: neural signals can take place in milliseconds.
Hormonal messages are graded events that may take seconds, minutes or even hours to
occur. Hormones can mediate long-term processes, such as growth, development,
reproduction and metabolism.
Generally there is more control over neural than over hormonal signals.
When a neural impulse arrives at a presynaptic terminal, an influx of Calcium ions causes
vesicles containing neurotransmitters to move toward the pre-synaptic membrane. The
vesicles fuse with the membrane and release the neurotransmitter into the synaptic cleft. The
neurotransmitters travel a distance of only 20-30 nanometers to the membrane of the
postsynaptic neuron where they bind with receptors.
Hormones manufactured in the Golgi apparatus of an endocrine cell also move toward the
cell membrane in vesicles that fuse with the membrane, releasing the hormone. However,
hormones then enter the circulatory system and may travel from 1mm to 2 m before arriving
at a cell of a target tissue where they bind with specific receptors.
Hormones are also similar to cytokines, chemical signals produced by cells of the immune
system, and may interact with cytokines to affect behavior, especially when individuals are
ill or stressed.
Because of their structure, certain chemicals in the environment can mimic natural hormones
and are generally referred to as endocrine disruptors. If such chemicals enter the food chain
or water supply, they can affect the same hormone-behavior pathways as natural hormones.
Hormones can only directly influence cells that have specific receptors for that particular
hormone, so called target-cells. Interaction of a hormone with its receptor starts a series of
cellular events that eventually lead either to activation of enzymatic pathways or to effects on
gene expression and protein synthesis.
In the last case, the newly synthesized proteins may activate or deactivate other genes,
causing another series of cellular events. Sufficient numbers of appropriate hormone
receptors must be available for a specific hormone to produce any effects. Individual
differences in hormone concentration generally do not affect behavior.
Recently, an additional mechanism has been reported: behavioral effects of hormones of
hormones that are not caused by activation of the genetic machinery are called nongenomic
effects of hormones.
Different ways in which hormones affect cells:
- Alter the rate of normal cell function
- Change cellular morphology or size
- Affect neuronal growth and development
- Induce/inhibit programmed cell death throughout nervous system
