Chapter 6 Flashcards

(64 cards)

1
Q

Females exhibit greater selectivity than males in

A

mating-partner choice

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2
Q

During breeding seasons, male vertebrates are capable of

A

sexual behavior all the time

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3
Q

During breeding seasons, male vertebrates are capable of sexual behavior all the time.In contrast, females exhibit

A

great fluctuations in sexual behavior

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4
Q

Estrus and anestrus

A

Female can be both estrus and anestrus : when ready to mate female is estrus, the rest of the time the female is anestrus, estrus females are more attracted to males than when they are anestrus: estrus spend more time near and looking for males than anestrus

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5
Q

Females find males more attractive when in

A

estrus

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6
Q

Males find females in __ more attractive than __ females

A

Males find females in estrus more attractive than anestrus females

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7
Q

Males prefer to mount

A

estrus females

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8
Q

Only __ females will permit mating to take place

A

estrus

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9
Q

__ are involved in expression of estrous behaviour in rats and dogs

A

the ovaries

Ovaries are the main source of estrogen + progesterone: impact on periphery but also on CNS

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10
Q

in females, hormones associated with __ maturation affect nervous system underlying mating behaviour

A

Hormones associated with ova maturation affect nervous system underlying mating behavior
(Hormones associated with ova maturation affect nervous system underlying mating behavior)

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11
Q

length estrous cycle

A

4 or 5 days

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12
Q

estrous cycle can be divided into 3 stages:

A

Diestrus (48 h)
Vaginal Proestrus (12 h)
Vaginal Estrous (36h)

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13
Q

length of diestrous component of estrous cycle

A

about 48h

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14
Q

what happens during diestrus 1

A

follicles are developped

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15
Q

what characterizes Diestrus 2:

A

Fully developed egg with granulosa and theca cells: but not released

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16
Q

what is the length of vaginal proestrus

A

12h

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17
Q

what happens during vaginal proestrous

A

This is when ovulation occurs and egg is released into fallopian tube

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18
Q

what is the length of vaginal estrous

A

about 36h

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19
Q

what happens during vaginal estrous

A

The corpea luteum (remainder of follicle after egg was released)
This structure can further develop if there is further copulation

If there is no copulation will degrade
Corpus luteum is important in secreting progesterons and plays a role into implantation of egg into uterine wall (if fertilization)

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20
Q

The female is ready to mate at which stage of estrous cycle

A

vaginal proestrous

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21
Q

what happens in ovaries is reflected in __

A

behaviour
ex: female is most receptive during ovulation

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22
Q

ovulation occurs when female is the most receptive in terms of

A

behaviour

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23
Q

area that is bigger in females

A

anteroventral periventricular nucleus

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24
Q

why is anteroperiventricular nucleusof males smaller than females ?

A

males early on produce androgens: testosterone travels in blood to brain: diffuse in the membrane of neurons (steroids are lipophilic and can pass through membrane). Inside the neuron they are converted to estradiol, which binds to its receptor (forms steroid-receptor complex) and binds to DNA in presence of coregulator: inducing apoptosis

females do not produce androgens as much early on: so this does not happen

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25
APVN (anteroventral periventricular nucleus) plays an important role :
in hormonal surge for ovulation to occur + for female to be receptive
26
kisspeptin binds to its receptor on neurosecretory cells in __ those cells when kisspeptin bound start producing __
Kisspeptin: binds to receptor on neurosecretory cells in hypothalamus: those cells when kisspeptin bound start producing gonadotropin releasing hormones: GTRH
27
Describe what happens when FSH and LH bind to female gonads
LH bind on Thecca cells and produce androgens (testosterone), testosterone converted into estrogen in granulosa cells through aromatase (aromatase active when FSH is bound to granulosa cells) LH can bind to granulosa cells and produce progesterones as well
28
two important brain regions in regards to surge / positive feedback in females
anteroPeriventricular Nucleus superchiasmatic nucleus (SCN)
29
APV receives input from SCN which allows
apv to time its release of kisspeptin
30
APV really important because leads to
surge in hormones
31
Once every cycle: sex steroid hormones produced by females gonads instead of putting break on further release lead to
even more release by impacting APV: at that point in time that region (because of projections from SCN is ready to release kisspeptin) Kisspeptin binds to neurosecretory cells that release GTRH SCN also has receptors for estrogen
32
female is most receptive when
in vaginal proestrus (female is "estrus" in vaginal proestrus)
33
what happens during vaginal proestrous
surge in LH: LH by binding to thecca cells in gonads leads to production of testosterone (which is then converted to an estrogen like we have seen):rgis increases levels of estrogens slowly but surely: then there is a spike in estrogen: spike involves kisspeptin and positive feedback (ventralperiventricular nucleus +SCN)
34
During proestrous: surge in LH: LH by binding to theca cells in gonads leads to production of testosterone (which is then converted to an estrogen): this increase levels of estrogen slowly but surely then spike in estrogen: spike involves kisspeptin and positive feedback: once egg released we go back to
negative feedback:
35
Why FSH always high :
involved in development of the follicle throughout cycle , not only involved in hormone production also involved in development of follicle which contains the egg
36
during vaginal proestrous we see spike in estrogen and we also see spike in:
progesterone (remember: estrogen + progesterone best match for female to engage in lordosis and in that order): spike in progesterone happens AFTER spike in estrogen (sequence is important in regards to ovulation and behaviour -lordosis) Once ovulation occurs, estrogen dramatically decreases, progesterone decreases slower
37
during the rest of the time (aka outside proestrus when female is no longer estrous) neurosecretory cells that produce GTRH are still activate in part by kisspeptin its kisspeptin coming from
arcuate nucleus
38
In both sexes: kisspeptin from __ involved in negative feedback
arcuate nucleus
39
6 Basic components to mammalian female production
* Courtship * Mating * Ovulation * Pregnancy * Parturition (giving birth) * Lactation
40
Females spend more time in __ phase than in __ phase
41
Beach’s (1976) scheme of female sexual behavior (3)
* Attractivity * Proceptivity * Receptivity (lordosis)
42
Beach's scheme of female sexual behaviour: describe (1/3): attractivity
attractivity is related to males: how attractive the female is to the male
43
How can you measure attractivity?
you can measure that is by place preference: you have two females one in a specific chamber and male in middle: allow male to roam around: then the male you can measure and see how much time the male spends with who:
44
baboons find females with __ attractive
baboons find females with enlarged genitals attractive
45
Describe the study that was done to measure attractivity
6 different male monkeys were presented with ovariectomized female (same female was treated with estrogens or no estrogens)
46
What was the conclusions of the attractivity study with monkeys?
obviously all monkeys preferred female when treated with estrogens: however they had different ratings : sp hormones are important for attractivity but it is not the only thing involved
47
__ seem to be involved in attractivity, but non-hormonal factors as well
steroid hormones seem to be involved in attractivity, but non hormonal factors as well
48
describe proceptivity
-Reflects female’s underlying motivational state * Observed in female’s efforts to establish and maintain proximity to males Also in alternating approaches and withdrawals by the female
49
proceptivity can be observed in:
female’s efforts to establish and maintain proximity to males
50
What are the three types of alternating approachers and withdrawals by the female during proceptivity
full solicitation partial solicitation interception
51
describe the study they did to determine that hormone (estrogen) was important in proceptive behaviour
3 groups: (1)ovariectomized + estradiol (2)ovariectomized, no estradiol "control" (3)nonpregnant "control' measured proceptive behaviour (approach/contact/groom/presentation) use a male that is not in breeding season (females not in breeding season either, but one of the group is artifiically put in one by estrogen) despite male not showing interest in femal, females treated with estrogen still engage in behaviour
52
All these type of solicitation behaviours involve
hormones; estrogen
53
are hormones important in proceptive behaviour?
yes
54
describe receptivity (3/3)
* The consummatory phase * Female reactions that are necessary and sufficient for fertile copulation * Much evidence as to the role of estrogen in receptivity (estrogen, progesterone and sensory stimuli from mounting of male all important in lordosis)
55
important brain regions in lordosis
in hypothalamus : MPOA but MOST IMPORTANTLY VENTRAL MEDiAL NUCLEUS (VMN) estrogen binds to receptors in VMN -> medial regions of the brain (midbrain central gray + midbrain reticular formation) -> medullar reticular formation -> spinal cord -> motor neurons (ventral horn) ->deep back muscles
56
Describe the study done on Estrogen Receptors
Study Summary: Estrogen Receptors and Female Sexual Receptivity Objective: To investigate the role of estrogen receptors, specifically estrogen receptor alpha (ERα), in female sexual receptivity using knockout mice. Method: Subjects: Female mice either: Knockout (ERα -/-): Lacking estrogen alpha receptors Control: Normal expression of ERα All mice were ovariectomized (removal of ovaries to eliminate endogenous hormone effects) Two hormone treatments administered: Estrogen alone Estrogen + progesterone Results: Controls: Showed sexual receptivity (lordosis behavior) in both treatments, especially with estrogen + progesterone. Knockouts: Showed no receptivity or lordosis at all, regardless of hormone treatment. Conclusion: Estrogen alone is not sufficient — estrogen must bind to ERα to promote sexual receptivity. ERα is critical: Knockout females lacking ERα do not respond to hormonal cues. This supports the idea that receptor presence (not just hormone availability) is essential for behavior. Additional Experiment: To rule out male behavior differences: Researchers measured the number of mounts by males toward both knockout and control females. Males mounted both types of females equally. However, there was no intromission with knockouts, confirming that the issue lies with female receptivity, not male interest.
57
describe the role of estrogen in promoting lordosis (3 hypothesis)
(1) trigger hypothesis (2)maintenance hypothesis (3) cascade hypothesis
58
describe the trigger hypothesis in regards to the role of estrogen in promoting lordosis
you only need acute injection or short lived treatment of estrogen to then observe lordosis later on
59
describe the maintenance hypothesis in regards to the role of estrogen in promoting lordosis
Need constant treatment estrogen
60
describe cascade hypothesis (role of estrogen in promoting lordosis)
need pretreatment estrogen, wait some time and then give another acute injection first injection: change nervous system second injection:hormones need to be there again to act on those changes:
61
* Manipulations that mimic hormonal profile of estrus behavior in ovariectomized mouse/hamster: Inject with estradiol early one morning * Later inject with progesterone * Subsequently, female displays lordosis in response to the appropriate stimulation: difference in VMN estradiol implants and VMN estradiol + systemic progesterone injection
VMN estradiol implants → weak lordosis * VMN estradiol + systemic progesterone injection → lordosis as in natural estrus
62
Estradiol priming leads to __
Estradiol priming leads to progesterone receptor production
63
describe the study where knockout mice were used to examine the involvement of progesterone and estradiol
Objective: To assess how the absence of progesterone receptors (PR) affects female sexual receptivity (measured via lordosis quotient, LQ). Groups Compared: Wild type (+/+): Full expression of progesterone receptors Heterozygous (+/–): Partial expression of PRs PRKO (–/–): No progesterone receptors Experimental Design: All mice were primed with estrogen first (to mimic physiological hormonal sequence). Followed by progesterone administration alone. Lordosis quotient (LQ) was measured over 6 weeks as an index of receptivity. Results: Wild type: Showed a steady and strong increase in lordosis behavior, reaching ~80 LQ by week 6. Heterozygous: Moderate increase in LQ, plateauing slightly below wild type. PRKO (–/–): Barely responded; LQ stayed very low (~10 or less) across all weeks. Conclusion: Progesterone receptors are essential for normal sexual receptivity. Estrogen priming alone is insufficient; progesterone must bind to its receptor to trigger lordosis behavior. PRKO mice fail to exhibit lordosis, confirming the necessity of progesterone receptor signaling.
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