Unit 3: Biological Sex Differences

Question 1

What are the 3 classes of steroid hormones that serve different functions?

Answer 1

Glucocorticoids
Mineralcorticoids
Androgens

Question 2

What 3 types of androgens are produced in the gonads?

Answer 2

Estrogen
Progesterone
Testosterone

Question 3

What is testosterone responsible for?

Answer 3

The differentiation of male sex organs.

Question 4

What are estrogen and progesterone responsible for?

Answer 4

Coordinating the menstrual cycle in women.

Question 5

What does typical testosterone exposure look like in boys?

Answer 5

Begins in prenatal weeks 8-24, when testes first develop.
A second surge occurs after birth, from 2 weeks - 4 months

Question 6

What does the aromatization hypothesis suggest?

Answer 6

That the “masculinization” of the brain occurs due to exposure of the metabolites of testosterone on estrogen receptors, a process that doesn’t happen in females due to ovaries not producing testosterone

Question 7

What are the tracts associated with each sex?

Answer 7

Mullerian = female
Wolffian = male

Question 8

What is responsible for bi-potential gonads developing into testes and what is the mechanism?

Answer 8

The SRY gene on the Y chromosome.
Sertoli cells (found in the testes) secrete anti-Mullerian hormone, which causes the Mullerian tract to regress (weeks 8-9 of pregnancy).
Sertoli cells then activate Lydig cells to produce testosterone, which stimulates the development of the parts of the male reproductive system

Question 9

What occurs if no anti-Mullerian hormone is secreted in the initial critical period?

Answer 9

The Wolffian tract will regress and the Mullerian tract will become the fallopian tubes, uterus, and cervix

Question 10

Though females do not have the SRY gene, what proteins are thought to be at play?

Answer 10

FOXL2 or FIGX might work to repress male sex organ transcription factors

Question 11

How are external sex organs formed?

Answer 11

All fetuses have a common undifferentiated embryonic structure that develops into either female or male genitalia.
DHT is responsible for this structure forming the prostate, penis, and scrotum in male fetuses.

Question 12

What are ORGANIZATIONAL EFFECTS?

Answer 12

The effects that steroid hormones have on a developing organism

Question 13

What are ACTIVATIONAL EFFECTS?

Answer 13

the effects of steroid hormones during the pubertal/postpubertal period
presumably due to the effects that estrogen and testosterone had on neural structures during the organizational period

Question 14

What is ANDROPAUSE?

Answer 14

when androgen levels are below a certain threshold and cause sexual dysfunction and loss of bone mass; treated with testosterone supplements

Question 15

What is SEXUAL DIMORPHISM?

Answer 15

distinct differences between the size and appearance between the sexes of an animal, in addition to differences in the actual sex organs themselves

Question 16

What is the MENSTRUAL CYCLE?

Answer 16

The monthly series of changes the body goes through to prepare for pregnancy

Question 17

What is MENOPAUSE?

Answer 17

the gradual cessation of the menstrual cycle in women, typically beginning in the 40s and reaching conclusion by late 50s
associated with decreases in hormones, bone density loss, and hot flashes; treatment may include hormone replacement

Question 18

What type of directional systems do men use more effectively?

Answer 18

Euclidean-directions - basing navigation on geometrical cues

Question 19

What type of directional systems do women use more effectively?

Answer 19

landmarks, landmark-based directions

Question 20

What are the details of Turner’s Syndrome?

Answer 20

X-linked DSD that occurs 1/2500 female births
individuals lack a secondary sex chromosome, or if it is present, it is severely malformed or expressed inconsistently
potential deficits in nonverbal learning, including spatial ability

Question 21

What type of verbal/spatial skills do women generally excel at, compared to men?

Answer 21

Perceptual speed: rapidly selecting and identifying items
Speed naming tasks
Superior ability to access verbal labels, verbal memory

Question 22

What is the nature of Androgen-insensitivity syndrome and testosterone in the brain?

Answer 22

XY individuals with AIS are unresponsive or partially so to testosterone, which can disrupt or halt the masculinization process.
If the form of AIS is complete, the individual will lack body hair, and present and identify as female&raquo_space; this suggests that gender identity and sexual orientation are likely affected by this process

Question 23

What are some features of Male-To-Female transgender individuals and treatment?

Answer 23

estrogen and progestin treatment are combined with anti-androgens
MtF individuals exhibit a female-like size of a nucleus in the hypothalamus; estrogen receptors here were more similar to those of genetic women than genetic men
MtF individuals have better verbal memory than genetic men prior to reassignment; performed poorer on mental rotation tasks following hormone treatment

Question 24

What are some features of Female-To-Male transgender individuals and treatment?

Answer 24

androgen treatment
FtM individuals demonstrate poorer verbal memory prior to reassignment than genetically female controls
Administration of testosterone improved visuospatial ability and impaired verbal fluency in FtM individuals

Question 25

What is the COMMISSURAL SYSTEM?

Answer 25

involved in transmitting information between and right and left hemispheres of the brain

some have reported the anterior commissure is larger in gay men than straight men; others have not observed this difference

Question 26

What are GLUCOCORTICOIDS?

Answer 26

part of the stress response that occurs via the activation of the hypothalamic-pituitary-adrenal (HPA) axis

males and females differ in their levels of circulating glucocorticoids and the degree of release following stress, may also contribute to sex differences in cognitive behaviour

Question 27

What do we know, generally, about biological sex differences?

Answer 27

occur in the CNS, are not limited to reproductive behaviours
some differences are small, but a number of behaviours, like spatial and navigational, exhibit larger differences
any discussion of sex differences is also a discussion of group differences, and many individuals do not follow the trend of their sex

Question 28

TRUE OR FALSE: Rhesus monkeys exhibit sex-typed toy preferences?

Answer 28

TRUE

Question 29

What is DHT?

Answer 29

The hormone that instigates the development of the penis, scrotum, and testicles during fetal development