Reproductive Behavior

Question 1

What are sexually dimorphic behaviors?

Answer 1

this refers to the difference in behavior as it relates to your individual sex assigned at birth
these are behaviors that refer to courting, mating, parental behavior, and most forms of aggression
these behaviors are influenced by biological and environmental factors

Question 2

What is the difference between sex and gender?

Answer 2

Sex: genetic/physiological characteristics of males and females in a species (XX vs. XY)
Gender: socially influenced by culture and learning
Gender identity: a person’s sense of self as masculine, feminine, both, or neither regardless of genitalia
Gender role: activities and traits associated by society with a particular sex
Gender identity and roles are specifically human and influenced by culture

Question 3

What are our sex chromosomes?

Answer 3

Sex chromosomes are found on the 23rd pair and are either XX or XY, the father determines the sex of the offspring
Gametes: sperm or ovum

Question 4

What are the organizational effects of our sex chromosomes?

Answer 4

occur in prenatal (before birth) development where sex organs and CNS are developed

Question 5

What are activation effects?

Answer 5

these occur later in life and consist of the production and release of gametes (puberty)

Question 6

What are gonads?

Answer 6

testes or ovaries
the first 6 weeks of gestation, we are undifferentiated
Y chromosome gene contains Sry, which is a protein that signals to the testis-determining factor whether or not this fetus needs testes
the absence of Sry will cause a fetus to develop ovaries

Question 7

What causes the creation of our internal sex organs?

Answer 7

Mullein system: female internal sex organs precursor
Wolffian system: male internal sex organs precursor
Testes secrete 2 types of hormones: anti-mullerian hormone (stops female system development) and androgens (testosterone and dihydrotestosterone stimulate Wolffian system)

Question 8

What causes the creation of our external sex organs?

Answer 8

Dihydrotestosterone stimulates male development. If this is not present, female development occurs

Question 9

What is Persistent Mullein duct syndrome?

Answer 9

a genetic (mutation) disorder of sexual development that either does not produce or lacks the receptors for anti-Mullerian hormone
XY males with internal organs for both sexes and neither system functions (masculinization without defeminization)

Question 10

What is Androgen insensitivity syndrome?

Answer 10

XY male that lacks androgen receptors
- no internal sex organs (defeminization without masculinization)
- external genitals are female: usually identify as female
- female development at puberty, except no periods or pubic hair

Question 11

What is Turner Syndrome?

Answer 11

XO female that does not develop ovaries. Female still has internal and external sex organs

Question 12

What is the sex hormone for females and what does it do?

Answer 12

Estrogen
- ovaries secrete estradiol, which stimulates secondary sex characteristics (breasts)
- does not affect axillary and pubic hair, this comes from adrenal androgens

Question 13

What is the sex hormone for males and what does it do?

Answer 13

Androgens
- testes secrete testosterone and stimulates secondary sex characteristics
- gonads produce low levels of opposite-sex hormones

Question 14

What is the hormonal control of female reproductive cycles?

Answer 14

Menstrual cycle: monthly variation in hormones and fertility
- anterior pituitary gland releases follicle-stimulating hormones, which promotes the growth of the ovarian follicle
- ovarian follicle then produces estradiol as it develops
- the increase in estradiol leads to the luteinizing hormone from anterior pituitary gland and this causes the follicle to release an ovum (this is called ovulation)
- the corpus luteum is the remnant of the follicle and this releases estradiol and progesterone so the uterus can prepare for implantation

Question 15

What is the hormonal control of sexual behavior in lab animals for females?

Answer 15

sexual behavior requires estrogen, followed by progesterone
- this facilitates receptivity (willingness to allow sex), proceptivity (the extent to which a female will initiate sex or mating), and attractiveness
- without the estrogen and/or progesterone, females will not be sexually receptive

Question 16

What is the hormonal control in lab animals for males?

Answer 16

requires testosterone in rodents – castration blocks sexual behavior but injections can restore the behavior
- pituitary hormones are released at ejaculation: oxytocin in the posterior facilitates orgasm, prolactin in the anterior inhibits male sexual behavior (cannot orgasm for a little bit)

Question 17

How does androgen affect organizational effects on behavior?

Answer 17

Females: lack of early androgen exposure leads to adult behavioral feminization (normal sexual behavior as an adult)
- early androgen exposure in female rodents promotes behavioral defeminization (estrogens do not elicit receptivity to males; do not want to have sex with men) and behavioral masculinization (elicits male sexual behaviors)

Males: lack of androgens in critical period (shortly after birth) cause adult feminization and demasculinization (male sexual behaviors)

Question 18

What are the sexual behaviors in humans?

Answer 18

Females: female hormones do not control a woman’s sexual behavior
- women are more likely to initiate sex in the middle of their cycle, however, this can be affected by a woman’s desire to become pregnant, may cause women to masturbate
- oxytocin facilitates affection, sexual interest, and orgasm

Males: positive association between testosterone and sexual activity
- peak testosterone levels (15-25) – increased sexual desire, declines with age
- castration and GnRH blockers decrease sexual desire and activity
- testosterone antagonists decrease fantasies and criminal sexual behavior
- increased testosterone in women also have these affects of increased sexual desire

Question 19

What are the effects of pheromones?

Answer 19

The Vomeronasal organ (VNO) allows for pheromones to influence sexual attraction and behavior
Effects in animals:
- Lee-Boot effect: females housed together, without males will disrupt others’ estrous cycles (cyclical pattern of physiological changes induced by reproductive hormones in females, disrupted by pregnancy)
- Whitten effect: synchronization of estrous cycles of groups of females when exposed to male odor
- Vandenbergh effect: acceleration of female puberty caused by male odor
- Bruce effect: termination of pregnancy when exposed to male odor that is not the father’s

If a man’s VNO is dysfunctional, they do not exhibit normal male sexual behavior and are less territorial over females while mating