PSYC 273 Lecture Notes - Lecture 8: Allomone, Pheromone, Castration
Chapter 8 Notes
Genitals and Gender: What Makes Us Male and Female
• Cloacal Exstrophy: a rare medical condition in which XY individuals are born completely
lacking a penis.
Part 1: The Endocrine System
• Hormones: a chemical, usually secreted by an endocrine gland, that is conveyed by the
bloodstream and regulates target organs or tissues.
o Try to balance the body.
Hormones act in a great variety of ways throughout the body.
• Endocrine Glands: a gland that secretes hormones into the bloodstream to act on
distant targets.
• Contrasted with exocrine glands: use ducts to secrete fluid outside the body (tear
glands, salivary glands, sweat glands).
• Our Current Understanding of Hormones Developed in Stages
o Castration: removal of testicles.
o Today we know that testes make and release testosterone.
• Neural and hormonal communications differ in 3 ways:
o Neurotransmitters travel to precise destinations. Hormones spread through the
body, but only influence cells with the proper receptor.
o Neural messages are rapid and hormonal messages are slower (longer lasting,
slow changes).
o Distance traveled: synaptic cleft is tiny while hormones may travel over a meter
via blood.
• Hormones are one of several types of chemical communication. The chemicals we call
hormones when discussing their endocrine function can act as neurotransmitters.
o Endocrine Communication: chemical signal is a hormone released into the
bloodstream to selectively affect distant target organs.
▪ Endocrine: referring to glands that release chemicals to the interior of
the body. These glands secrete the principal hormones used by the body.
o Synaptic Communication: the released chemical signal diffuses a tiny distance
across the synaptic cleft and causes a change in the postsynaptic membrane.
▪ Synapses: the cellular location at which information is transmitted from a
neuron to another cell.
o Pheromone Communication: chemicals can be used for communication not only
within an individual, but also between individuals (ex:
▪ Pheromones: a chemical signal that is released outside the body of an
animal and affects other members of the same species.
o Allomone Communication: some chemical signals are released by members of
one species to affect the behavior of individuals of another species (ex: flowers
attract bees).
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▪ Allomone: a chemical signal that is released outside the body by one
species and affects the behavior of other species.
• Ex: like bees taking pollen from one flower to another.
• Hormones can be classified by chemical structure.
o Most hormones fall into 1 of 3 categories. Each interact with different receptors.
▪ Peptide Hormone (Protein Hormone): a hormone that consists of a string
of amino acids.
▪ Amine Hormone (Monoamine Hormone): a hormone composed of a
single amino acid that has been modified into a related molecule, such as
melatonin or epinephrine.
▪ Steroid Hormones: any of a class of hormones, each of which is
composed of 4 interconnected rings of carbon atoms.
Bethold’s Epeiet:
• When you cut out the testes, you get an animal that looks and behaves more like a hen.
• Replacing the testes allows you to get the behavior and looks of a rooster again.
• Sensitive periods of development: organizational effect: Organization of the brain and
the body is determined early in life.
• Activation Effect: later in life, hormones activate behaviors, but their effects tend to be
less dramatic and short lived.
• Androgen exposure during sensitive period necessary for long lasting changes.
Hormones Act on a Wide Variety of Cellular Mechanisms
• Hormones initiate actions by binding to receptor molecules.
o 3 classes of hormones exert their influences on target organs in 2 different ways.
▪ Amino acids: Peptides and Amine Hormones use one way. Bind to specific
receptor proteins on the surface of the cell. Act through second
messengers.
• Water soluble. Cannot pass through the membrane.
• Second Messengers: a slow-acting substance in a target cell that
amplifies the effects of synaptic or hormonal activity and
regulates activity within the target cell.
• What determines whether a cell responds to a particular peptide
hormone?
o Only cells that produce the appropriate receptor proteins
for a hormone can respond to that hormone.
o Peptide hormones usually act within seconds or minutes
(fast for a hormone, slow for neural activity).
▪ Steroids exert influence in another way. Steroids cross through
membrane and bind inside cell itself.
• Lipid soluble: can slide through the membrane.
• Can easily pass through cell membranes so their receptors are
located inside the target cell.
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• When the steroid binds to the receptor they it binds to DNA and
controls the expression of certain genes.
• Slower acting than the peptide and amine hormones.
• Study where steroids are active by injecting radioactively tagged
molecules of the steroid and observing where they accumulate.
• Techniques of Modern Behavioral Endocrinology
o What hormones affect which behavior?
▪ Observe the behavior of many individuals.
• Take away something and observe changes.
• Inject a hormone to see if it changes the behavior.
▪ Observe the behavior of animals that lack the receptors for a certain
steroid.
▪ Delete the gene for a given hormone receptor.
• Knockout Organism: an individual in which a particular gene has
been disabled by an experimenter.
• Ask which behaviors are different.
▪ Compare two of the same animal.
▪ A hormone that act permissively permits the display of the behavior, but
something else determines how much of the behavior each individual
exhibits.
o What are the target cells?
▪ What parts of the brain are normally affected by this hormone?
• Inject an animal with radioactively labeled testosterone and wait
for the hormone to accumulate in the brain regions that have
receptors for the hormone.
o Autoradiography: a staining technique that shows the
distribution of radioactive chemicals in tissues.
o Immunocytochemistry (ICC): a method for detecting a
particular protein and then chemical methods are used to
leave a visible reaction product around each antibody.
o In Situ Hybridization: a method for detecting particular
RNA transcripts in tissue sections by providing a nucleotide
probe that is complementary to, and will therefore
hybridize with, the transcript of interest.
o Once areas have been determined they become
candidates for the places the hormone works to change
behavior.
o Implant pellets of the hormone in different parts of the
brain to see if it returns the behavior to normal.
• Hormones can have different effects on different target organs. Each act on more than
one target organ.
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