Sexual Development & Behavior

Question 1

SEX HORMONES

Answer 1

Pituitary Gland and gonads (ovaries/testes) are the primary sources of the sex hormones.

1. Pituitary Gland = produces the gonadotropic hormones
2. Ovaries = secrete estrogen and progesterone
3. Testes = testosterone and androstenedione
4. Estrogen and androgen are secreted by both sexes, but females produce more estrogen and males more androgens.

Question 2

Sexual Differentiation During Fetal Development

Answer 2

Differentiation of the gonads begins approx. 6-8 weeks after conception.

First differentiation dependent on sex chromosomes, but development is largely result of hormonal exposure!

1. For a genetic male fetus to develop male genitalia, the fetus must be stimulated by androgen during the critical period of dvlp, which is the second trimester.
2. lack of androgen leads to a female pattern of devlpmt in both genetic males and females.
3. Hormonal mistake = genetic female is exposed to early androgen = she will have andrenogenital syndrome, having male reproductive organs and boyish bx (w/o increase tendency for homosexuality).

Question 3

Sexual Dimorphism

Answer 3

Brain is sexually dimorphic, sex-related differences in its physical appearance.

size differences in corpus callosum, hippocampus, and SCN.

Hypothesize that this is related to differential exposure to androgens during prenatal and postnatal dvlp.

later affect brain functioning.

Question 4

Puberty

Answer 4

increase in gonadal hormones influences the emergence of Secondary Sex Characteristics and Reproductive system.

Hypothalamic-Pituitary-Gonadal Axis: hypothalamus secretes chemicals that stimulate the pituitary gland, which releases the ganodotropic hormones that stimulate testoterone and sperm in testes or ovulation and estrogen production by the ovaries.

Puberty onset also affected by genetics, environmental circumstances such as nutrition, exercise, family size, and temperature.

Puberty in 1st world earlier due to better health care and nutrition.

Question 5

Adult Sexual Behavior

Answer 5

In lower animals, sex hormones play an extremely important role in adult sexual behavior.

But, as we ascend the phylogenetic scale, the sex hormones become increasingly less important, while learning and experience become more important.

1. human females less link between sx hormone and bx. menopause and ovariectomy has litttle or no effect on sex drive.
2. males, testosterone levels are tied to sex interest and appetite with a minimum threshold (above which does not matter).
3. Sildenafil (Viagra) acts on penile tissue, not androgen levels.

Question 6

Menopause

Answer 6

Menopause in late 40’s and early 50’s.

decreased estrogen produces a variety of emotional and physical symptoms.

hot flashes, fatigue, mood swings, nausea, loss of bone mass, reduced elasticity of skin, vaginal dryness.

Question 7

Hormone Replacement Therapy (HRT)

Answer 7

HRT during menopause reduces the negative physical/emotional symptoms but no evidence that it improves the sex drive.

Some research say it is not advisable due to increased risk of blood clots, stroke, and breast cancer.