11.1 Sex And Hormones Questions

Front 1

*Describe the three types of sex hormones and the three ways they can exert their effects.

Back 1

-Androgens, estrogens, and progesterone act in three ways:

-bind to receptors (rapid effects)

-enter cells and activate proteins

-bind to receptors that bind to chromosomes (activate or inactivate certain genes)

Front 2

*Describe the roles of genes and hormones in the organization of physical and behavioral sex differences in mammals.

Back 2

-During an early sensitive period, a high level of testosterone causes the external genitals to develop the male pattern, and a low level leads to the female pattern.

-Sex hormones early in life influence development in parts of the hypothalamus, amygdala, and other brain areas, such as the larger sexually dimorphic nucleus in males.

-Prenatal injections of testosterone into female monkey fetuses led to increased masculine-type play after they were born. Her clitoris grows larger than normal, and her behavior is partly masculinized. She approaches sexually receptive females, mounts them, and makes copulatory thrusting movements rather than arching her back and allowing males to mount her.

Front 3

*Describe the activating roles of hormones on reproductive behaviors and neurotransmitters in certain brain areas.

Back 3

-Estrogens increase the sensitivity of the pudendal nerve, which transmits tactile stimulation from the vagina and cervix to the brain.

-Testosterone increases sensitivity in the penis.

-Testosterone increases the release of nitric oxide (NO), which increases blood flow to the penis.

-Testosterone and estradiol prime the medial preoptic area (MPOA) and several other brain areas to release dopamine.

-MPOA neurons release dopamine strongly during sexual activity, and the more dopamine they release, the more likely the male is to copulate.

Front 4

*Describe the hormonal processes that control women’s menstrual cycles and pregnancy, including the effects of birth-control pills.

Back 4

-After the end of a menstrual period, the anterior pituitary releases follicle-stimulating hormone (FSH), which promotes the growth of a follicle in the ovary.

-The follicle nurtures the ovum (egg cell) and produces several types of estrogen, including estradiol.

-Toward the middle of the menstrual cycle, the levels of LH, FSH, and estradiol increase

-FSH and LH combine to cause the follicle to release an ovum.

-The remnant of the follicle (now called the corpus luteum) releases the hormone progesterone, which prepares the uterus for the implantation of a fertilized ovum.

-Progesterone also inhibits the further release of LH.

-Toward the end of the menstrual cycle, the levels of LH, FSH, estradiol, and progesterone all decline.

-If the ovum is not fertilized, the lining of the uterus is cast off (menstruation), and the cycle begins again.

-If the ovum is fertilized, the levels of estradiol and progesterone increase gradually during pregnancy.

-The most widely used birth-control pill, the combination pill, containing estrogen and progesterone, prevents the surge of FSH and LH that would otherwise release an ovum. The estrogen–progesterone combination also thickens the mucus of the cervix, making it harder for a sperm to reach the egg, and prevents an ovum, if released, from implanting in the uterus.

Front 5

*Describe the endocrine influences on parental behaviors.

Back 5

-Oxytocin stimulates contractions of the uterus during delivery of a baby, stimulates the mammary gland to release milk, and helps the mother and infant to bond

-Prolactin is necessary for milk production and certain aspects of maternal behavior (such as retrieving the young when they wander away from the nest); it inhibits leptin so the mother rat can eat more than usual

Front 6

**Which hormones are likely to be found more abundantly in males than in females?

Back 6

androgens

Front 7

**If a female rat is injected with testosterone during the last few days before being born or the first few days afterward, the injection will:

Back 7

cause her reproductive structures to look like those intermediate between female and male

Front 8

**If a female rat fetus developed without any alpha-fetoprotein, her hypothalamus would:

Back 8

develop in a partly masculinized manner

Front 9

**Damage to the medial preoptic area of the hypothalamus in rats would most likely result in:

Back 9

decreased sexual activity

Front 10

**A female rat is more likely to develop a preference for a cage where sexual activity with a male rat occurs if:

Back 10

she can control the timing of sexual activity

Front 11

What does the SRY gene do?

Back 11

The SRY gene (sex-determining region on the Y chromosome) 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.

Front 12

How do sex hormones affect neurons?

Back 12

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.

Front 13

What would be the 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?

Back 13

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. Genital development depends mostly on the presence or absence of androgens and is nearly independent of estradiol levels.

Front 14

From the standpoint of protecting a male fetus's sexual development, what are some drugs that a pregnant woman should avoid?

Back 14

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 cans produce mild abnormalities. Obviously, the results depend on both quantities and timing of exposure to these chemicals.

Front 15

How would the external genitals appear on a genetic female rat that lacked alpha-fetoprotein?

Back 15

A female that lacked alpha-fetoprotein would be masculinized by her own estradiol, as researchers have in fact demonstrated (Bakker et al., 2006).

Front 16

What evidence most directly links children's toy play to prenatal hormones?

Back 16

Girls whose mothers had higher testosterone levels during pregnancy tend to play with boys' toys more than the average for other girls. Boys whose mothers had higher phthalate exposure tend to play with boys' toys less than the average for other boys.

Front 17

By what mechanism do testosterone and estradiol affect the hypothalamic areas responsible for sexual behavior?

Back 17

Testosterone and estradiol prime hypothalamic cells to be ready to release dopamine. They also increase sensitivity in the genital area.

Front 18

What is the explanation for why married men tend to have lower testosterone levels than single men of the same age?

Back 18

Men with lower testosterone levels are more likely to get married than are men with higher testosterone levels.

Front 19

At what time in a woman's menstrual cycle do her estradiol levels increase? When are they lowest?

Back 19

Estrogen levels increase during the days leading up to the middle of the menstrual cycle. They are lowest during and just after menstruation.

Front 20

What behavioral change occurs after orgasm, and which hormone is responsible?

Back 20

Anxiety decreases after orgasm because of the release of the pituitary hormone oxytocin.

Front 21

What factors are responsible for maternal behavior shortly after rats give birth? What factors become more important in later days?

Back 21

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 vomeronasal responses that would tend to make her reject them. Experience with the young maintains maternal behavior after the hormone levels begin to drop.