Chapter 5 - Sex Hormones and Human Sexuality

Question 1

What are hormones?

Answer 1

chemical messengers that are released by endocrine organs and carried throughout the body via the circulatory system; provide cxs between the NS and the reproductive system

Question 2

how are hormones released into the bloodstsream?

Answer 2

through endocrine organs such as the gonads; small amounts produce strong and lasting effects

Question 3

how are hormones regulated?

Answer 3

by feedback signals from every organ effected, especially the brian

Question 4

what are se3x hormones?

Answer 4

regulate sexual maturity and reproduction

Question 5

three main sex hormones

Answer 5

androgens, estrogens, progestogens
(oxytocin and vasopressin can also be considered sex hormones)

Question 6

what is the HPG axis?

Answer 6

Hypothalamic‐pituitary‐gonadal axis; communication system between areas of the brain (the hypothalamus and pituitary gland) and the gonads that affects the production and release of sex hormones

Question 7

what does the brain use to regulate sex hormone production?

Answer 7

the HPG axis

Question 8

what is the hypothalamic hormone?

Answer 8

GnRH (gonadotrophin releasing hormone)

Question 9

what are the pituitary hormones?

Answer 9

FSH (follicle simulating hormone); LH (luteinizing hormone)

Question 10

what are the gonadal hormones?

Answer 10

testosterone (from testes); estrogen/progesterone (from ovaries)

Question 11

in males, testosterone operates in a ____ loop

Answer 11

negative feedback

Question 12

male system (?)

Answer 12

LH binds to cells inside the testes and causes them to secrete testosterone

Question 13

explain the negative feedback loop for testosterone

Answer 13

Hypothalamus directly monitors testosterone
levels; this influences gonadotropin‐releasing hormone (GnRH) levels (released by hypothalamus); GnRH levels influence LH production (from pituitary); LH influences Testosterone production

ex: Low T > hypothalamus increases GnRH >
pituitary increases LH > T rises
9

Question 14

explain the negative feedback loop for sperm production

Answer 14

inhibin secreted by testes regulates the negative feedback loop for FSH; operates in a different area of the hypothalamus than T production

ex. Low Inhibin ‐> Hypothalamus increases GnRH ‐> Pituitary increases FSH ‐> Testes manufacture sperm

Question 15

what regulate the female menstrual cycle

Answer 15

the interaction of the different components of the HPG axis

Question 16

4 phases of menstrual cycle

Answer 16

1. Follicular phase
2. Ovulation
3. Luteal phase
4. Menstruation

Question 17

describe the follicular phase

Answer 17

pituitary secreting high levels of FSH, stimulates a follicle in the ovary to bring an egg to the final stage of maturity; follicle also secrets estrogen at this time (affecting the endometrium)

ex. Low Estrogen/Inhibin ‐> Hypothalamus increases GnRH ‐> Pituitary increases FSH ‐> follicle/egg matures
-negative feedback loop

Question 18

describe ovulation phase

Answer 18

Estrogen + Inhibin levels have risen to a high level, causing FSH levels to start to fall
– Consequently, the high estrogen levels stimulates the hypothalamus to produce GnRH, which stimulates the pituitary to produce LH
* So High E ‐> Increases GnRh ‐> Increasess LH
* This LH surge is what triggers ovulation
* Positive feedback loop; different area of hypothalamus
– The follicle ruptures open and releases a mature egg

Question 19

describe the luteal phase

Answer 19

After releasing an egg, LH levels cause the follicle
in the ovary to turn into a glandular mass of cells
called the corpus luteum
* Corpus luteum secretes progesterone
– The progesterone from corpus luteum stimulates glands of the endometrium (uterus) to start secreting a nourishing substance
-Corpus luteum will only produce progesterone for about 10‐12 days (if no pregnancy)
– If no pregnancy, the corpus luteum withers and
the uterine lining cannot be maintained due to the decline in progesterone
– Sharp decline in both Estrogen and Progesterone levels at end of luteal phase

Question 20

describe menstruation phase

Answer 20

– Shedding of the inner lining (endometrium) of the uterus
– Discharged through cervix and vagina
– Triggered by the sharp decline of Estrogen and
Progesterone at end of luteal phase
– FSH levels are now starting to rise again

Question 21

average length of menstrual cycle

Answer 21

20-26 days (about 28)
In a 28 day cycle:
* Day 1 to 4/5 = menstruation
* Day 5 to 13 = follicular phase
* Day 14 = ovulation
* Day 15 to 28 = luteal phase

Question 22

what are some issues that typically arise with the menstrual cycle

Answer 22

Dysmenorrhea; Endometriosis; Amenorrhea; Premenstrual syndrome (PMS) and Premenstrual dysphoric disorder (PMDD)

Question 23

the development of secondary sex characteristics is triggered by the activation of ____

Answer 23

the HPG axis during puberty

Question 24

male secondary sex characteristics

Answer 24

incr muscle mass, facial hair, growth of testes, lowering of the voice

Question 25

female secondary sex characteristics

Answer 25

widened hips and pelvis, breast growth, incr fat tissue in arms/thighs/hips/butt

Question 26

role of hypothalamus

Answer 26

highly responsive to hormones; provides sex hormones and influences sexual acts and the individual's perception of sexuality

Question 27

prenatally, the brain is very sensitive to ____

Answer 27

androgens and estrogens -may affect identity and sexual attraction

Question 28

the sexual brain is connected to brain regions that play a role in ____

Answer 28

thinking, perceptions, self control; sexuality, attraction, desire, and a sense of sexual self cannot be uncoupled from life experience

Question 29

how do hormones affect sexuality?

Answer 29

strong evidence that sex hormones may directly affect sexual attraction, desire, and performance; androgens and estrogens play a direct role in genital and subjective arousal ex. administration of testosterone can increase genital sexual arousal in both women and men

Question 30

the relationship between sex and sex hormones is ____

Answer 30

reciprocal; sexual activity incr testosterone in men and women; Intimate physical contact (even of a non‐sexual nature) can increase testosterone in women; sexual arousal decreases the stress hormone cortisol and increases estradiol in women

Question 31

how does sexual activity and other life factors affect hormone levels?

Answer 31

viewing erotica appears to incr testosterone levels in men and estradiol levels in females; imagining sexual interactions (fantasies) incr T levels in women; there is a bidirectional relationship between T levels and relationship status in women

Question 32

what hormones work together and play a role in sexual/other reproductive behaviours?

Answer 32

oxytocin and vasopressin

Question 33

oxytocin is associated with ____

Answer 33

childbirth, lactation, maternal behaviour, bonding

Question 34

vasopressin is associated with ____

Answer 34

multiple aspects of human social and sexual functions such as increased heart rate and fluid balances

Question 35

how do smells (of sex hormones) lead to sexual behaviour?

Answer 35

smells can activate areas in our emotional brain (limbic system) outside of conscious awareness

Question 36

what are pheromones

Answer 36

produced in the apocrine glands (armpit and pubic areas); synthesis is controlled by androgens in males and females

Question 37

what are the four pheromones identified in humans?

Answer 37

Territorial, menstrual/fertile, sexual, and maternal‐infant

Question 38

what is major histocompatibility complex (HCM)?

Answer 38

compounds that are found in genital pheromones and may communicate genetic info to sexual partners

Question 39

what is perimenopause

Answer 39

signals a decline in fertility for women; usually in late 40s

Question 40

when is a woman considered menopausal

Answer 40

no menstrual period in 12 months or more

Question 41

menopausal women may experience a decline in libido due to ____

Answer 41

declining estrogen and estradiol levels

Question 42

what is the most common sexual dysfunction among women of all ages?

Answer 42

low desire; affects 34%-43% of women in Western countries

Question 43

from young adulthood to menopause, what happens to testosterone levels?

Answer 43

levels of circulating testosterone decline gradually

Question 44

what is andropause?

Answer 44

falling testosterone levels in males over 50

Question 45

what happens during andropause?

Answer 45

low libido; decreased strength/energy/stamina; incr irritability; decr enjoyment of life

Question 46

aging men may experience what along with andropause?

Answer 46

bone and muscle mass loss; incr body fat; breast development; changes in cognitive functions

Question 47

low libido is typically caused by what in older men?

Answer 47

hypogonadism -can cause erectile dysfunction -can be treated with androgen therapy