Reproductive behaviour

Question 1

• Sry gene causes ….

Answer 1

• Sry gene causes male internal genitalia - testes.

Question 2

• No Sry gene causes ………..

Answer 2

• No Sry gene causes female internal genitalia - ovaries.

Question 3

Puberty is initiated by …

Answer 3

Puberty is initiated by the arcuate nucleus of the hypothalamus

Question 4

kisspeptin causes the anterior hypothalamus to release ,………….

Answer 4

kisspeptin causes the anterior hypothalamus to release Gonadotropin-releasing hormone (GnRH).

Question 5

• GnRH causes pituitary to release ….

Answer 5

• GnRH causes pituitary to release FSH and LH in both sexes.

Question 6

• FSH and LH cause testes to release ….

Answer 6

• FSH and LH cause testes to release testosterone and ovaries to release estradiol.

Question 7

Hypothalamus and pituitary are the ….

Answer 7

Hypothalamus and pituitary are the master controllers of the endocrine system.

Question 8

The combination of estradiol + progesterone signals …

Answer 8

The combination of estradiol + progesterone signals the fertile phase of the female’s cycle.

Question 9

different sexual moves in rats>

Answer 9

• Proceptivity – female approach, ear wiggling
• Attractiveness – male engagement/mounting
• Receptivity – female willingness
• Lordos – female posture

Question 10

what do gonadectomised male rats need for activational effects in adulthood

Answer 10

The Interaction between activational and organization effects is revealed by a series of experiments.
Males and Females are gonadectomised at birth and either given hormones at that time (to study organisational effect) or in adulthood (to study activational effects).
Table shows that gonadectomised males need replacement hormones at birth AND as an adultin order to show activational effects in adulthood.

Question 11

what did Van Goozen find

Answer 11

Initiation of sexual activity between human partners.
Males initiate sex evenly across the female menstrual cycle.
Females initiate sex more often during ovulation (the fertile phase).

Question 12

what did

Bagatell et al. find

Answer 12

• Gave males a GnRH hormone antagonist- blocking testosterone
• Measured time in weeks
• From week 4-6, reduced frequency of sexual desire
• In the alternate, there is a testosterone replacement, they have continued sexual desire
• Male sexual behaviour is governed by testosterone

Question 13

sexual orientations explained

Answer 13

• Male heterosexual = brain masculinized and defeminized
• Female heterosexual = neither masculinized nor defeminized
• Male homosexual = neither masculinized nor defeminized
• Female homosexual = brain masculinized and defeminized
• Male and female bisexual = masculinized but not defeminized

Question 14

default brain is…

Answer 14

female

Question 15

what did Balthazart J (2016) atrgue

Answer 15

Individuals who prefer woman (heterosexual males and lesbians) have been masculinised and defeminised, and have a masculine index to ring finger ratio (and longer limbs).
Individuals who prefer males (heterosexual woman and homosexual men) have been feminized and have a feminine index to ring finger ratio (and short limbs).

Question 16

what is Congenital adrenal hyperplasia (CAH)

Answer 16

• Abnormal androgens in genetic females.
• Produces ambiguous genitalia.
• ≈33.3% genetic females with CAH identify as homosexual or bisexual compared to ≈2% of females as a whole.

Question 17

what is Androgen insensitivity syndrome

Answer 17

• Testosterone should masculinisation and defeminise morphology.
• Genetic males with androgen insensitivity syndrome develop as females.
• They may be complete or partial females depending on the level of insensitivity.
• Typically female external genitalia, but also with testes (internal) and without uterus or Fallopian tubes.
• Typically favour male partners as do heterosexual females, suggesting neural feminisation.

Question 18

what is an Androgen insensitivity syndrome example

Answer 18

Joan of Arc - twice intimately examined to verify she was indeed a woman but apparently never menstruated.

Question 19

What differences are there in the male vs. female brain which are responsible for male sexual behaviour?

Answer 19

Animals: Sexually dimorphic nucleus of the medial preoptic area MPA of the hypothalamus.

Humans: interstitial nucleus of the anterior hypothalamus number 3 INAH3.

Question 20

Post mortem examination indicates that the INAH3 is …..

Answer 20

Post mortem examination indicates that the INAH3 is 2-3 times larger and has a higher cell density in heterosexual males than homosexual males and females.

Question 21

what did Balthazart J (2016) find

Answer 21

No difference in heterosexual men with and without AIDS, suggesting this did not cause the INAH3 differences.

Question 22

MPA in male rats sexual behaviour

Answer 22

o MPA lesions abolish sexual behaviour
o Electrical stimulation increases copulatory behaviour
o Sexual behaviour increases firing rate
o Glutamate (excitatory) infusion increases sexual behaviour
o 3-7 times larger in male than female rats
o Enlargement relies on androgens in the womb and shortly after birth indicating that it is biologically determined rather than socially
o Gonadectomy in males decreases sexual behaviour and can be reinstated by testosterone administered into the MPA showing antinational effect
o MPA contains testosterone receptors

Question 23

amygdaala in male rats sexual behaviour

Answer 23

o The medial amygdala connects to the MPA
o Medial amygdala also contains testosterone receptors
o Lesions of the medial amygdala disrupt sexual behaviour
o Medial amygdala received input from the vomeronasal organ, detecting pheromones which stimulate sexual behaviour
o Implication is that the amygdala transmits sexual excitation of external sensory sources to stimulate the MPA which then controls behaviour by downstream circuits

Question 24

• Nucleus paragigantocellularis (nPGI) of the medulla in male rats sexual behaviour

Answer 24

o Spine contains the thrusting and ejaculation reflex and are held under tonic inhibition by the nucleus paragigantocellularis (nPGI)
o Inhibitory GABA projections from the MPA disinhibits these reflexes, stimulating thrusting and ejaculation
o The nPGI send inhibitory serotoninergic connection to the spine to inhibit erection and ejaculation
o Application of serotonin (5-HT) to spinal cord suppresses erection and ejaculation
o Men taking selective serotonin reuptake inhibitors (SSRIs) often report a side effect of difficulty achieving erection and ejaculation, may be mediated by nPGI

Question 25

• Periaqueductal gray matter (PAG) of midbrain in male rats sexual behaviour

Answer 25

o The MPA also inhibits PAG normally activates the nPGI, again releasing the thrusting and ejaculation reflexes controlled by the spine

Question 26

• Central Tegmental Field (CTF) in male rats sexual behaviour

Answer 26

o Receives somatosensory signals from genital stimulation promoting activating the MPA which then disinhibits the thrusting and ejaculation reflexes

Question 27

• Ventromedial nucleus of hypothalamus (VMH) in female rats sexual behaviour

Answer 27

o VMH lesions abolish lordosis (spinal reflex akin to make thrusting), even if treated with estradiol and progesterone
o Electrical stimulation of VMH facilitates lordosis
o Instra-VMH estradiol + progesterone primes lordosis in ovariectomised female
o Intra-VMH progesterone antagonists block lordosis
o Medial amygdala received input from the vomeronasal organ detecting pheromones which stimulate sexual behaviour (same as males)
o Mechanical stimulation of the vagina with rat dildo increases activity of VMH and medial amygdala neurons
o The BMH has an excitatory connection with the PAG
o OAG contains oestrogen and progesterone receptors, and lesions abolish lordosis, suggesting downstream controller
o The PAG has excitatory connections with the nPGI which in turn controls the muscles governing lordosis
o Suggests an excitatory circuit from VMH-PAG-nPGI produces lordosis
o Recall that male sexual behaviour was held under tonic inhibition
o Little is known about circuits for complex human sexuality?
o There are a whole range of other circuits that control pair bonding which you can read about in the book

Question 28

what does FSH stand for

Answer 28

follicle-stimulating hormone

Question 29

what does LH stand for

Answer 29

luteinizing hormone