PSY 350 Sexual Orientation and Reproduction

What hormone starts the menstrual cycle?

FSH released by the anterior pituitary gland.

What does FSH do?

Stimulates the maturation of ovarian follicles.

What hormone does a maturing ovarian follicle release?

Estradiol.

What does estradiol do during the menstrual cycle?

Causes the uterine lining to develop.

What triggers the LH surge?

Estradiol reaches a critical level.

What does the LH surge cause?

Triggers ovulation (release of an egg).

What happens to the empty ovarian follicle after ovulation?

It becomes the corpus luteum.

What hormones does the corpus luteum release?

Estradiol and progesterone.

What happens if pregnancy does not occur?

The corpus luteum dies, hormones decrease, and menstruation begins.

What hormone controls sexual behavior in male rodents?

Testosterone.

What hormones control sexual behavior in female rodents?

Estradiol and progesterone.

What happens to progesterone before a female rat's receptive period?

Progesterone increases after the rat is primed with estradiol.

What happens to estradiol and progesterone during estrus?

Both hormones are low.

What happens to hormones during metestrus?

Both increase moderately.

What happens to hormones during diestrus?

Both hormones decrease again.

What happens to hormones during proestrus?

Both increase more and the phase ends with ovulation.

What is oxytocin's role in sexual behavior?

Released during orgasm in males and females; contributes to muscle contractions.

What does oxytocin help contract in males?

Smooth muscle in the ejaculatory system.

What does oxytocin help contract in females?

The vagina and uterus.

What is behavioral defeminization?

Prenatal androgen exposure inhibits female sexual behavior in adulthood.

What is behavioral masculinization?

Prenatal androgen exposure enables male sexual behavior in adulthood.

What is the difference between masculinization and defeminization?

Masculinization enables male behavior; defeminization inhibits female behavior.

What hormone has an activational effect on male human sexual behavior?

Testosterone.

Do women require estradiol or progesterone for sexual interest?

No. Women can experience sexual interest and engage in sexual behavior without them.

How can ovarian hormones affect women's sexual behavior?

Changes across the menstrual cycle may influence sexual interest.

What other factors affect women's sexual behavior?

Partner initiation and desire to avoid or achieve pregnancy.

How can androgens affect women's sexual interest?

They may help estradiol increase sexual interest.

What are pheromones?

Chemicals that communicate information between members of the same species.

What organ detects pheromones?

The vomeronasal organ.

What information can pheromones communicate?

Sex, estrous condition, and identity.

What is the Lee-Boot effect?

Female mouse urine odorants lengthen and eventually stop other females' estrous cycles.

What is the Whitten effect?

Male mouse urine odorants reverse the Lee-Boot effect and synchronize females' cycles.

What is the Vandenbergh effect?

Male odorants accelerate the onset of puberty in female mice.

What is the Bruce effect?

Odor from a male other than the one that impregnated a female mouse causes her to abort.

What effects can pheromones have on humans?

May influence menstrual cycles, mood, attractiveness ratings, and brain activity.

What are gametes?

Sex cells (sperm and ova).

How are gametes produced?

Through meiosis.

What is meiosis?

Cell division that produces cells with one chromosome from each pair.

How many chromosomes does each human gamete contain?

23 single chromosomes.

What happens during fertilization?

A sperm and ovum join, combining their 23 chromosomes each.

How many chromosome pairs are present after fertilization?

23 pairs (46 total chromosomes).

What gene controls the development of testes?

The SRY gene.

What does the SRY gene do?

Controls the development of testes from undifferentiated gonads.

What develops without the SRY gene?

Ovaries develop.

What controls the development of internal sex organs?

Organizational effects of hormones.

What is the Wolffian system?

The internal male reproductive system that develops with male sex hormones.

What causes the Wolffian system to develop?

Exposure to male sex hormones.

What is the Müllerian system?

The internal female reproductive system that develops without male sex hormones.

What happens without exposure to male sex hormones?

The Müllerian system develops.

What hormone causes male external genitalia to develop?

Dihydrotestosterone (DHT).

What develops without exposure to DHT?

Female external genitalia.

What are organizational effects of hormones?

Hormone effects that control the initial development of sex organs and genitalia.

What are masculinization and defeminization examples of?

Organizational effects of hormones.

What are primary sex characteristics?

Sex organs and genitalia that develop before birth.

When do organizational effects occur?

During early development, before birth.

What are activational effects of hormones?

Hormone effects that occur later and activate sexual characteristics.

When do activational effects begin?

Around puberty and continue throughout adulthood.

What causes activational effects?

Mature gonads producing sex hormones.

What is the main difference between organizational and activational effects?

Organizational effects develop sex organs; activational effects occur later, around puberty.

What do activational effects influence?

Secondary sex characteristics and sexual development at puberty.

What controls sexual reflexes like erection and ejaculation?

The spinal cord.

What are examples of male sexual reflexes?

Sexual posturing, erection, and ejaculation.

What role does the brain play in male sexual behavior?

Provides excitatory and inhibitory control over erection and ejaculation.

What happens when the MPA is stimulated?

Copulatory (mating) behavior occurs.

What happens when the MPA is destroyed?

Copulatory behavior is permanently abolished.

What is the MPA?

The medial preoptic area, a brain region important for male sexual behavior.

What is the SDN?

A part of the MPA involved in male sexual behavior.

What happens when the SDN is destroyed?

Mating behavior is impaired.

What brain activity increases during ejaculation in men?

Activity in reinforcement mechanisms, thalamic nuclei, lateral putamen, and cerebellum.

What is the most important forebrain region for female sexual behavior?

The ventromedial nucleus of the hypothalamus (VMH).

What happens when the VMH is destroyed?

Female copulatory behavior is abolished.

What happens when the VMH is stimulated?

Female sexual behavior is facilitated.

Which hormones facilitate female sexual behavior in the VMH?

Estradiol and progesterone.

What receptors are found in the VMH?

Estrogen and progesterone receptors.

What does estradiol's priming effect do in the VMH?

Increases the number of progesterone receptors.

Where do steroid-sensitive neurons of the VMH send their axons?

To the periaqueductal gray matter (PAG) in the midbrain.

What does the PAG help control in female sexual behavior?

Sexual responses through connections with the medullary reticular formation.

What brain activity increases during orgasm in women?

Activity in regions similar to male ejaculation, plus the PAG.

What are oxytocin and vasopressin?

Peptides that act as both hormones and neurotransmitters.

What roles do oxytocin and vasopressin play in pair bonding?

They help facilitate bonding between partners.

Which hormone plays the biggest role in male pair bonding?

Vasopressin.

Which hormone plays the biggest role in female pair bonding?

Oxytocin.

What happens when vasopressin receptors are added to the basal forebrain of male voles?

Polygamous male voles begin showing monogamous behavior.

What is the basal forebrain?

A brain region involved in behaviors such as pair bonding.

What role does oxytocin appear to have in humans?

It is involved in a variety of social behaviors.

What is the difference between oxytocin and vasopressin in pair bonding?

Vasopressin is more important in males; oxytocin is more important in females.

What are examples of rodent maternal behavior?

Nest building, delivering pups, cleaning, warming, nursing, and retrieving pups.

Why do mother rodents retrieve their pups?

To return pups that have been moved away from the nest.

How do mother rodents help their pups urinate and defecate?

They stimulate the pups to eliminate waste.

Why do mother rodents eat their pups' urine?

To recycle water, which can be scarce.

What hormone facilitates nest-building behavior?

Progesterone.

What is the principal hormone of pregnancy?

Progesterone.

Which hormones facilitate maternal behavior when given in a pregnancy-like sequence?

Progesterone, estradiol, and prolactin.

What hormone facilitates the onset of maternal behavior?

Oxytocin.

Where do pregnancy hormones appear to act to influence maternal behavior?

The medial preoptic area (MPA).

What brain region is important for maternal behavior?

The medial preoptic area (MPA).

What is the neural pathway involved in maternal behavior?

MPA → VTA → NAC → ventral pallidum.

What does the MPA-VTA-NAC-ventral pallidum pathway do?

Helps make pups rewarding and increases motivation to care for them.

What happens in the mother's brain when she sees her pups?

Brain reinforcement mechanisms become activated.

What happens in women's brains when they look at pictures of their infants?

Similar reinforcement brain regions become more active.