Sexual Behaviour

Front 1

What is reproductive cycle called in primates? other animals?

Back 1

primates: menstrual cycle
other: estrous cycles
- controlled by hormones secreted by pituitary glands and ovaries

Front 2

describe a sexual encounter between two rats

Back 2

-female if receptive arches back (lordosis) and may entice male with sniffing and nuzzling .
-female also hops around and wiggles ears.
-male will mount several times and intromit on most ocassions but will only ejaculate after 8-15 intromissions.
- after a refractory period male will return to copulate again (responds more quickly to a new female)

Front 3

What will happen when a male rat encounters a female with ovaries removed?

Back 3

Males will ignore females whose ovaries have been removed but injections of estradiol and progesterone will increase her attractiveness. Ovariectomised rats are not sexually receptive but it can be produced by administering estradiol followed by progesterone t mimic natural hormone release

Front 4

Describe androgens and behavioural defeminization

Back 4

- Androgens are male sex steroid hormones which stimulate the development of the male sex organs.
- Main androgen is testosterone
- Androgens have a defeminizing effect; they inhibit the later development of anatomical or behavioural female
characteristics
- If a rodent brain is NOT exposed to androgens at a critical time during development (shortly after birth), and treated with estradiol and progesterone as an adult, the rat will engage in female sexual behaviour.
- If a male rat is castrated after birth and given injections of estradiol and progesterone as an adult, it will respond to the presence of another male by assuming lordosis, i.e. it acts as if it were a female.

Front 5

an animal which has not been exposed to androgens at birth (nonandrgenized) but then given female sex hormones as an adult will _______

Back 5

express female behaviour

Front 6

An animal that is nonandregenized at birth but then given androgens will _______

Back 6

show NO sexual behaviours at all.

Front 7

in order for a male rat to be male he must :

Back 7

have testes and must produce/be given testosterone early after birth

Front 8

if a rat is androgenized at birth and then given female sex hormones as an adult then he will______

Back 8

show no sexual behaviour

Front 9

if rat is androgenized and this is followed by more testosterone as adult he will_____

Back 9

of course show male sexual behaviour

Front 10

Define Pheromones

Back 10

chemicals that carry messages from one animal to another. in humans found in urine, vaginal secretion, saliva, tears

Front 11

Give the three examples of pheromones cycles

Back 11

1) Lee-boot effect: Groups of female rats when housed together show slowing down of their estrous cycle
2) Whitten Effect: Exposure to male odour (or urine) will begin the cycle again and the cycles will synchronise.
3) Vandenbergh effect: A female rat will show accelerated puberty if she is exposed to male odour (urine)
****castrated male has no effect!

Front 12

The Bruce Effect

Back 12

If a recently impregnated mouse encounters a male mouse other than the one she mated, the pregnancy will fail.
- This effect is caused by a substance in the ‘intact’ male urine which tells the women's body to stop.
- Thus, a male mouse is able to prevent the birth of infants carrying another male’s genes and subsequently impregnate the female himself.
** important evolutionary advantage

Front 13

The Vomeronasal Organ

Back 13

-mediates the effects pheromones have on repro cycle
- projects to olfactory bulb (removing bulb disrupts lee-boot, whitten, bruce and vandenbergh cycles)

Front 14

The VNO neurons respond when/to.... What happens when we delete a pheromone receptor from VNO in females?

Back 14

- respond only when a mouse actively investigates the mouth or anogenital region or another mouse.
-- responds to non-volatile compounds found in urine
- deleting a pheromone receptor from the VNO causes male sexual behaviour in females

Front 15

Medial Nucleus of Amygdala (receives axons from, projects to, role, lesions of this area cause...)

Back 15

- receives axons from olfactory bulbs, part of system that mediates effects of pheromones
- amygdala projects to preoptic area and ventromedial hypothalamic nuclei (arousal!)
- lesions to this region abolish sexual behaviour in males

Front 16

in humans, women who spend more time in male company have...

Back 16

shorter cycles

Front 17

androstadienone

Back 17

compound in human sweat which increases alertness and positive mood in females and decreases positive mood in males

Front 18

social explanation for sexual orientation

Back 18

there is no evidence of childhood affecting it

Front 19

biological explanation speculations for homosexuality

Back 19

- hetero and homosexual men have same levels of sex steroids
- male homosexual brains are neither masculinized nor defeminized
- female homosexual brains are masculinized and defeminized

Front 20

What role does Congenital Adrenal Hyperplesia CAH play in sex orientation?

Back 20

adrenal glands here secreteabnormal amounts od androgen prenatally which causes prenatal ,asculinization. therefore boys born with CAH develop as boys. Girls born with CAH are born with enlarged clitoris and labia fused together

Front 21

Androgen insensitivity syndrome

Back 21

males with this develop as females with female genetalia but also with testes and without a uterus or fallopian tubes
- lack of androgen from testes (once removed) prevents masculinization and most are just raised as girls with no reports of sexuality towards women

Front 22

name two brain structures which appear to be associated with a man's sexual orientation

Back 22

suprachiasmatic nucleus (SCN) of the hypothalamus, and the anterior commissure

Front 23

Bed nucleus of the stria terminals (BNST)

Back 23

larger in males than females, small in male transexuals (same size as a females) but normal male size in male homosexuals

Front 24

pair bonding in voles

Back 24

praire voles are monogamous, meadow voles promiscuous

Front 25

Vasopressin receptors; vasopressin receptor blockers

Back 25

-in ventral forebrain- high levels of them associated with monogamous animals more than polygamous ones
-blockers disrupt the formation of pair bonds
- * if you inject a modified virus containing the vasopressin gene into a ventral forebrain of polygamous male, will make him manogamous!!

Front 26

oxytocin and pair bonding in humans

Back 26

mating stimulates oxytocin release, and injecting it will facilitate pair bonding. Oxytocin causes relaxation, calmness, and trust

Front 27

Describe the meaning of the phase “Nature’s impulse is to create a female”

Back 27

if a rodent’s brain is not exposed to androgens during a
critical period of development, the animal will engage in
female sexual behavior as an adult (if the animal is then
given estradiol and progesterone).
behavioural defeminization prevents the rat from exhibiting female behaviour and behavioural masculinization promotes male behaviour

Front 28

Non-classical CAH

Back 28

Girls born with NCAH show normal female genitalia at birth and do not show signs of increased androgen levels until late childhood or adolescence.

Front 29

main differences between estrous cycle mammals and menstral cycle mammals

Back 29

the shedding of the lining, also mating on estrous cycles is linked to ovulation whereas most primates can mate at anytime

Front 30

ovarian follicles

Back 30

- small spheres of epithelial cells surrounding each ovum which releases estradiol

Front 31

ovulation

Back 31

LH causes the ovarian follicle to rupture, releasing the ovum. the ruptured follicle becomes a CORPUS LUTEUM which produces estradiol and PROGESTERONE (maintains uterine lining)

Front 32

What happened in the armpit compound study?

Back 32

took compounds from armpit of females and dissolved in alcohol and rubbed on lip of other females and they synched cycles

Front 33

AND, EST

Back 33

AND= pheromone produced by males, increases level of attractiveness of male to female.
EST= pheromone produced by females

Front 34

two peptides in brain related to monogamy

Back 34

vasopressin (plays a more important role in males) and oxytocin (more in females)

Front 35

Parturition

Back 35

giving birth

Front 36

describe maternal behaviour examples

Back 36

- make nests
- facilitate the birth process
- lick pups urine to transfer nutrients
-many mother rats will accept any pup given even if it is not her own
- maternal behaviour is affected by hormones but not controlled by them - even virgin rats will exhibit motherly behaviour if pups are placed wight them

Front 37

3 hormones that influence maternal behaviour; female nest building is facilitated by...

Back 37

progesterone, estradiol and prolactin (hormone necessary for milk production too); progesterone