Ch. 10.1. Sex and hormones Flashcards
What does the SRY gene do?
The SRY gene (sex-determining region on the Y chromo- some) causes the undifferentiated gonad of a mammal to develop into a testis, which then produces testosterone and MIH to direct development toward the male pattern.
How do sex hormones affect neurons?
Sex hormones, which are steroids, bind to receptors on the membrane, activate certain proteins in the
cell’s cytoplasm, and activate or inactivate particular genes.
What would be the external genital appearance of a mammal exposed to high levels of both androgens and estrogens during early development? What if it were exposed to low levels of both?
A mammal exposed to high levels of both male and female hormones will appear male.
One exposed to low levels of both will appear female. External genital development depends mostly on the presence or absence of androgens, and is nearly independent of estradiol levels.
From the standpoint of protecting a male fetus’s sexual development, what are some drugs that a pregnant woman should avoid?
Pregnant women should avoid alcohol, marijuana, haloperidol, phthalates, and cocaine because these drugs interfere with male sexual development.
Even aspirin and the chemicals lining bottles and cansproduce mild abnormalities. Obviously, the results depend on both quantities and timing ofexposure to these chemicals.
How would the external genitals appear on a genetic female rat that lacked alpha-fetoprotein?
A female that lacked alpha-fetoprotein would be mas- culinized by her own estradiol, as researchers have in fact demonstrated (Bakker et al., 2006)
Why is any individual’s brain more masculinized or feminized in some areas than others?
The mechanisms for sexual differentiation vary from one brain area to another. People vary in the genes, as well as the epigenetic influences, that modify brain development in different brain areas
What evidence most directly links children’s toy play to prena- tal hormones?
Girls whose mothers had higher testosterone levels dur- ing pregnancy tend to play with boys’ toys more than the average for other girls
What are the effects of phthalates on sexual development?
Phthalates inhibit testosterone production. Boys whose mothers had higher phthalate exposure tend to play with boys’ toys less than avrage for other boys
By what mechanism does testosterone affect the hypotha- lamic areas responsible for sexual behavior?
Testosterone primes hypothalamic cells to be ready to release dopamine.
What are two explanations for why married men tend to have lower testosterone levels than single men?
First, marriage decreases the need to seek sexual partners and therefore may lower the testosterone level.
Second, men with lower testosterone levels are more likely to marry and remain married.
At what time in a woman’s menstrual cycle do her estradiol levels increase? When are they lowest?
Estradiol levels increase during the days leading up to the middle of the menstrual cycle. They are lowest during and just after menstruation
When is a woman most likely to act sexy and initiate sexual activity?
During the periovulatory period.
What factors are responsible for maternal behavior shortly after rats give birth? What factors become more important in later days?
The early stage of rats’ maternal behavior depends on a surge in the release of the hormones prolactin and estradiol. A few days later, her experience with the young decreases the responses that would tend to makeher reject them. Experience with the young maintains maternal behavior after the hormone levels begin to drop
What is the main difference between organizing effects and activating effects of hormones?
Organizing effects are long-lasting, whereas activating effects are temporary.
How does sexual differentiation of the brain differ between rodents and primates?
In rodents, testosterone must be aromatized to estra- diol before it affects developing neurons.
