K. Hormones and Sex - Part 2

Question 1

What is the bipotential precursor

Answer 1

the genitals in humans that can either develop into female or male genitals

Question 2

What are the 4 parts of the bipotential precursor? Indicate what each develops into

Answer 2

1. glands -> head of the penis/clitoris
2. urethra fold -> fuses (male)/enlarges (female)
3. lateral body -> hood of clitoris/shaft of the penis
4. labioscrotal swelling -> scrotum or the lady vagorla

Question 3

a) label the image.
b) What is this showing
c) this is ______ after conception

Answer 3

a)
blue = gland
yellow = urethral fold
green = lateral body
pink = labioscrotl swelling
b) bipotential precursor
c) 6 wks

Question 4

a) when does genital differentiation occur?
b) What hormone dictates that differentiation?

Answer 4

a) 3 months
b) testosterone

Question 5

Describe what happens during the following times after fertilization for males
a) 6 wks - 2
b) 7 wks - 2
c) 9-12 wks
d) 12 wks

Answer 5

a) primordial gonads (internal reproductive ducts) and bipotential precursors (external reproductive organs)
b) SRY gene produces SRY protein + medulla of the gonads develope into the testes
c) testes secrete testosterone (develop Wolffian sys) + Mullerian inhibiting substance (degrades Mullerian sys)
d) differentiation of external reproductive organs via testosterone secretion

Question 6

When are the two times in life that sex hormones tend to surge?

Answer 6

1. during fetal development
2. puberty

Question 7

What are the 2 roles of puberty wrt sex hormone release

Answer 7

1. achieving fertility = maturation of the reproductive organs
2. development of secondary sex chromosomes

Question 8

during puberty
a) what releases the hormones needed?
b) What are the 3 types of hormones released

Answer 8

a) anterior pituitary
b)
1. growth hormones (GH) = develop bones and muscles
2. gonadotropic hormones (FSH + LH) = primary sex hormones
3. adrenocorticotropic hormones (ACTH) = some sex hormones

Question 9

Describe the following terms
a) sexual dimorphism
b) sex differences

Answer 9

a) used to describe certain sexual behaviors as being present in only one sex
b) used to describe certain sexual behaviours as being present in one sex on average but can sometimes be present in the other

Question 10

Describe what would happen wrt gonadotropin-releasing patterns in the following sits. indicate whether the result reflects the pattern for males/females.
a) gonadectomy
b) gonadectomy + testes transplant
c) gonadectomy + ovary transplant

Answer 10

a) both sexes develop a cycling pattern of gonadotropin release (female pattern)
b) both sexes develop a steady pattern of gonadotropin release (male pattern)
c) both sexes develop cycling pattern of gonadotropin release (female pattern)

Question 11

What are the gonadotrophin release patterns for the following
a) males
b) females

Answer 11

a) steady
b) cyclic

Question 12

What does perinatal mean?

Answer 12

before birth

Question 13

What does perinatal mean?

Answer 13

before birth

Question 14

What are the 2 ways to find sex differences in the brain? Provide an example for each

Answer 14

1. size = the medial preoptic area of the hypothalamus (males>females)
2. activity level = amygdala (females>males)

Question 15

what brain region is referred to as the sexually dimorphic nucleus? Why? - 3

Answer 15

the medial preoptic area of the hypothalamus b/c it is significantly large in males than females and seems to be correlated w/ male sexual behaviors

Question 16

Place the following phychological disorder as either more prominent in females, males, or relatively equal in both
a) major depressive disorders
b) schizophrenia
c) dyslexia
d) autism
e) eating disorders
f) ADHD
g) stuttering
h) anxiety
i) bipolar disorder

Answer 16

females = a, e, h
males = c, d, f, g, b (early onset)
both = b (behaviour), i

Question 17

Briefly describe the aromatization hypothesis

Answer 17

it discusses that sex differentiation that occurs during development is actually due to the conversion from high levels of testosterone to estradiol via the enzyme aromatase

Question 18

a) What are the 2 forms that testosterone can be converted to?
b) what enzyme is used to convert each
c) indicate which one is an estrogen/androgen
d) which types of receptors do each bind to?

Answer 18

a) estradiol + Dihydrotestosterone
b) aromatase + 5 alpha-reductase
c) estrogen + androgen
d) estrogen receptors + androgen receptors

Question 19

Sex steroids are all derived from _____ and are readily converted from one to the other

Answer 19

cholesterol

Question 20

using the aromatization hypothesis what are the results wrt hormone release patterns for the following sits. indicate which are female/male patterns + explain.
a) neonatal administration of testosterone
b) neonatal administration of testosterone + aromatase inhibitor
c) neonatal administration of dihydrotestosterone + inhibitor

Answer 20

a) steady pattern (male) b/c the testosterone is able to properly be converted to estradiol
b) cyclic pattern (female) b/c the inhibitor stops aromatase from converting the testosterone from being converted to estradiol
c) cyclic pattern (female) b/c dihydrotestosterone is a non-aromatizeable androgen (unable to be converted into estradiol by aromatase)

Question 21

What is neonatal

Answer 21

a new born

Question 22

According to the aromatization hypothesis estradiol masculinizes the brain. But then why doesn’t maternal estradiol cause a female embryo to develop into a male in utero?

Answer 22

This is b/c w/in the placenta there exist alpha-fetoproteins that bind to the maternal estradiol but not testosterone. Allowing the testosterone to travel up the placenta to the brain where it is then converted into estradiol.

Question 23

What prevents alpha fetoproteins from binding to the testosterone-converted estradiol w/in the fetal brain?

Answer 23

alpha fetoproteins are unable to pass the BBB

Question 24

Describe what is happening in this image

Answer 24

the testosterone that has traveled up the placenta is entering the neuronal cells. Where aromatase converts it into estradiol (estrogen) and binds to the estrogen receptor. This complex then translocates into the nucleus and acts as a transcription factor promoting the expression of proteins that will go off an masculinize the brain

Question 25

Describe what is happening in this image

Answer 25

the estrogen is caught by the alpha-fetoprotein preventing it from entering the fetal brain. The low [estrodiol] already in the brain binds to the estrogen receptor. This complex translocates into the nucleus and acts as a transcription factor promoting the expression of proteins that will go off and feminize the brain

Question 26

T or F - the aromatization hypothesis describes all the sexual differences b/w different brain regions

Answer 26

F - it only explains some brains areas that contain aromatase

Question 27

T or F - just like w/ the development of the reproductive ducts the female brian is the default as the male brain only develops due to the presence of testosterone

Answer 27

F - there are some estrogenic mech that influence the femininity of the female brain

Question 28

T or F - the presence/absence of the SRY gene on the Y chromosome is the only gene that dictates sex

Answer 28

F - there are other sex chromosomes that influence the brain development

Question 29

Describe androgenic insensitivity syndrome during the following developments
a) gonad
b) reproductive duct
c) genital

Answer 29

a) due to the presence of the SRY gene on the Y chromosome the medulla of the primordial gonad develops into testes
b) while the testes are fully fxnal the androgen receptors are unresponsive meaning the Wolffian sys never fully develops and the Mullerlan sys only partially develops due to the release of the Mullerlan -inhibiting substance
c) due to the unresponsiveness of the androgen receptors the scrotum never developed resulting the development of the female genitalia

Question 30

Describe androgenic insensitivity syndrome in one sentence

Answer 30

a sexual condition in which a genetic male forms the external sex organs of a female
due to androgen receptor unresponsiveness

Question 31

Why are ppl w/ androgenic insensitivity syndrome infertile?

Answer 31

B/c internally they don’t have a fully matured mullarlan sys meaning their uterus is underdeveloped and cannot allow for the growth of a fetus