PSYC 202 Study Guide - Midterm Guide: Mesonephric Duct, Y Chromosome, Wilder Penfield
Course CodePSYC 202
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1. Neural and hormonal communication work together to coordinate behavior. Provide
support for this statement by describing the milk letdown reflex in detail (including
the names of the critical cell groups, hormones and pathways).
a. Sensory stimulation at nipple when infant begins sucking --> goes to brain via
sensory neurons, interneurons attached to the spinal cord.
b. Nerve impulses sent to the hypothalamus (paraventricular and supraoptic nuclei
c. Neurons fire action potential down to their synapses into the posterior pituitary
gland where the neuron is attached to blood vessels. Oxytocin is released into
these blood vessels and it travels down the bloodstream and affects cells with
oxytocin receptors. In this case, it would be the tissue in the mammary glands,
and milk is released.
2. The organizational effects of androgen exposure around the time of birth
masculinize reproductive behaviors in rats and determine the activational effects of
hormones later in life. Evaluate this statement by discussing the experimental
evidence discussed in class. Clearly explain the experimental manipulation and
behavioral outcome. What are activational and organizational effects in the first
place (i.e. provide a definition)? Be sure to clearly explain the “default” relation
between organizational and activational effects in non-experimentally manipulated male
and female rats as well.
a. Organizational effects are the effects of gonadal hormone exposure before or
around the time of birth (early life). In male rats, the default is androgen exposure
after the first six weeks as an embryo, while in female rats, there are no
androgens or estrogens present. The presence of sex hormones masculinizes
the rat: SRY protein provided on the Y chromosome allows for the development
of testes, which stimulate production of testosterone (allow wolffian ducts to form)
and AMH (anti-mullerian hormone). Absence of both hormones leads to the
feminization of internal reproductive structures. Again, testosterone is converted
to DHT by 5 alpha reductase and allows for the formation of external male
genitalia, and absence of DHT allows for the formation of external female
b. When female rats were exposed to androgens early in life, they behaved as
males- when presented with a normal female rat, they displayed mounting
behaviors, typically seen in males.
c. When male rats were castrated at birth and treated with estradiol as an adult,
they displayed the lordosis in response to a male present and did not mount.
3. Agouti-related peptide (AgRP)-producing and Pro-opiomelanocortin (POMC)- producing
neurons in the arcuate nucleus of the hypothalamus each play a critical role in the
control of food intake. Which one is important for hunger/feeding, which one for
satiety? Discuss how these two cell groups are affected by peripheral inputs (and
name the peripheral inputs) that either signal hunger or satiety AND discuss, in detail,
the neural pathways, chemicals and receptors through which each of these cell
populations induce either feeding or satiety.
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