Sexual development

Question 1

adult sexual development: females

Answer 1

hips widen
breasts develop
uterus grows & menstration

Question 2

adult sexual development: males

Answer 2

larynx enlarges

ability to ejaculate

Question 3

3 main classes of hormone

Answer 3

Amino acid derivatives: synthesised from amino acid molecule
Peptides & proteins: chains of amino acids
Steroid hormones: synthesised from cholesterol (go through the cell membrane)

Question 4

What is a gonad?

Answer 4

reproductive gland
endocrine
contain sex chromosomes

Question 5

what hormone class influences sexual development?

Answer 5

steroid hormones

Question 6

three main types of sex steroid

Answer 6

Androgens (tesosterone) & estrogens (estradiol) & progestin

Question 7

pituitary glad contains what kind of hormone? Function? Example?

Answer 7

• Tropic hormone (stimulate release of other hormones from other glands)
• gonadotropin

Question 8

2 parts of the pituitary & function

Answer 8

1) Anterior pituitary – endocrine gland. Controls folicle stimulating hormone & lutenizing hormone
2) posterior pituitary – uses axonal transport. Vasopressin & oxytocin

Question 9

menstrual cycle - phases & prominent hormone

Answer 9

3 main phases:

1) Follicular phase (estradiol)
2) ovulatory phase (lutenizing hormone)
3) luteal phase (progesterone)

Question 10

hypothalamic control of the posterior pituitary

Answer 10

• vasop & oxytocin synthsised in nuclei of the hypo
• transported along axons to terminals in PP
• action potential releases the chemicals into bloodstream

Question 11

hypothalamic control of the anterior pituitary

Answer 11

• neuron FREE
• capillary system instead: hypothalamopituitary portal system (Harris, 1955)
• evidence: Schally, Kastin & Arimura, 1971

Question 12

3 main ways of hormonal regulation

Answer 12

neural signal regulation: CNS & PNS (autonomic)
regulation via hormones: i.e. tropic hormones
non hormonal chemicals: i.e. glucose/insulin

Question 13

sexual dimorphisms - what? who found?

Answer 13

male & female structural differences

de vries & sodersten, 2009

Question 14

Pfeiffer (1936) - what? Results? conclusion?

Answer 14

• semial - work with rats
  1) some rats gonadectomised (and some not) & some given transplants (and some not)
  Results: gonadectomising rats of either sex caused them to develop female cyclic pattern of release
  ALSO transplanting in testes into females = male pattern of gonadotropin release
  Conclusion: presence/absence of testicular hormones influences rats dev of pituitary release of gonadotrophin

Question 15

why was Pfeiffer wrong?

Answer 15

bc the release of gonadotrophin from the anterior pituitary is controlled by the hypothalamus not testicular hormones

Question 16

though it wasnt totally true, what did Pfieffer reveal?

Answer 16

role of androgens @ birth overriding preporgrammed female cyclic patterns of gonadal tropin relsease

Question 17

Balthazart & Ball (2006)

Answer 17

• renewed pfeiffer: included the hypothalamus

- aromatisation hypothesis

Question 18

aromatisation hypothesis – still an older theory

Answer 18

enzymes (aromatase) converts testosterone into estradiol which MASC the brain

Question 19

modern perspectives on sexual differentiation of the brain: 2 pieces of evidence

Answer 19

MULTIPLE mechanisms is what account for the change in human brains:

1) Jazon & cahill, 2010: sex chromosomes play their own part on gene expression (indep of hormones)
2) Bakker & Baum (2007): we DO need gonadal steroids - estradiol plays an important role

Question 20

male reproduction related behavioiur & testosterone

Answer 20

• Testosterone LEVELS don’t influence sex drive

- Removing testicles (completely no testosterone) does reduce sexual interest

Question 21

Female reproduction related behaviour & gonadal hormones

Answer 21

• menstrual cycle
• sexual behaviour is PARTLY controlled by hormones
  a) human females copulate outside of fertile window: only species (Ziegler, 2007)
  b) androgens seem to motivate sexual motivation in women who have had their ovaries removed

Question 22

Neural control of sexual behaviour

Answer 22

• association cortex (forgotten)

- hypothalamus

Question 23

structural diffs between male & female hypothalamus

Answer 23

1) Gorski et al (1978) - in rats: medial preoptic area (inc sexual dimorphic nucleus) = larger in males
2) suprachiasmatic nucleus: “ (Swaab et al. 1994)
3) anterior hypothalamus: “ (Allen et al. 1989)

Question 24

hypothalamus & male sexual behaviour

Answer 24

Medial preoptic area plays key role (domingues & Hull, 2005)

a) electrical stimulation of MPO elicits copulatory beh in rats ( rodriguez- manzo et al. 2000)
b) lesions affect rats motvation to engage in sexual behaviour (Paredez, 2003)
c) circuits seem to be involved with dopaminagenic pathways (motivation?) Dominguez & Hull 2005

Question 25

hypothalamus & female sexual behaviour

Answer 25

ventromedial nucleus

a) bilateral lesions in rats - more likely to attack suitors
b) VMN & periaquiductatal grey - lesions lead to eliminations of sexual behaviour

Question 26

Sexual orientation & genes

Answer 26

shows a genetic basis (bailey & pillard, 1991)

Question 27

Sexual orientation & early hormones

Answer 27

1) homo & heterosexuals dont vary in their hormone levels
2) develops early: perinatal castration of males - inc liking of adult males & increasing testosterone levels in women - inc chance of liking adult women
~~~ evidence in humans is sparse (Diamond, 2009)

Question 28

Sexual orientation & brain structure

Answer 28

Levay (1991)

• suprachiasmatic N bigger in heterosexual males (feminisation of brain?)
• not been replicated (Rahnman, 2005)

Question 29

sexual differentation of the body

Answer 29

Sry protein causes medulla of the indifferent gonad to turn to testes
Sry = on Y chromosome