Title: SAPOLSKY Ch' 7 SEX AND REPRODUCTION
1SAPOLSKY Ch. 7SEX AND REPRODUCTION
24 STAGES OF REPRODUCTIVE BEHAVIOR
- Sexual attraction
- Appetitive behaviors
- Copulation
- Refractory phase
34 STAGES OF REPRODUCTIVE BEHAVIOR
- Sexual attraction
- Attractivity
- Role of estrogen in females
- Coordinates fertility and attractiveness
- Sex skin swelling in some primates
4Sexual swellings of female baboons
54 STAGES OF REPRODUCTIVE BEHAVIOR
- Sexual attraction
- Pheromones
- Chemicals released by an animal that influence
the behavior (especially sexual behavior) of
other members of its species.
6Atlas moth, Attacus atlas
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94 STAGES OF REPRODUCTIVE BEHAVIOR
- Sexual attraction
- Males
- Size, strength, territory, nest, money, lack of
physical imperfections - Womens menstrual cycle may affect their
preference for more masculine faces.
10SURVIVAL OF THE SPECIES REQUIRES REPRODUCTIVE
SUCCESS. NEANDERTHALS FAILED!
MANY ANIMALS ADVERTISE REPRODUCTIVE STATUS WITH
COLOR
MALE VERVET MONKEY
11- Sexual attraction
- Males
- Counterintuitive antlers, peacock tails, dark
manes, bright colors - May signify that males are so fit they can
overcome their disadvantages
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134 STAGES OF REPRODUCTIVE BEHAVIOR
- Appetitive behaviors (motivation)
- Proceptivity in females
- Hopping, darting, ear-wiggling in rats
- Eye contact and proximity
- Role of menstrual cycle in women (small effect)
- Timing of most copulation is determined by female.
144 STAGES OF REPRODUCTIVE BEHAVIOR
- Appetitive behaviors
- Males
- Birds elaborate songs and/or nests
- Proximity to female
154 STAGES OF REPRODUCTIVE BEHAVIOR
- Copulation
- Receptivity in females
- Rats a few hours every 4 or 5 days
- Lordosis necessary for copulation
- Rats spontaneous ovulators but need patterned
stimuli to induce luteal phase/pregnancy - Monkeys social variables
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184 STAGES OF REPRODUCTIVE BEHAVIOR
- Copulation
- Males mounts, intromissions, ejaculation
- Great variability among and within species re.
stimulation needed for ejaculation - Dogs begin to ejaculate as soon as intromission
is achieved. - Rats 7-10 brief intromissions before ejaculation
194 STAGES OF REPRODUCTIVE BEHAVIOR
- Refractory phase
- Ultrasonic song in male rats
- Sleep EEG
- Coolidge effect (male will copulate with new
female) - Pair bonding in prairie voles
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21Neural circuitry in females
- Receptivity
- Lordosis posture necessary for copulation in
most mammals
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23 24Neural circuitry in female rats
- Ventromedial nucleus
- Has estrogen receptors
- Sends output to midbrain ? brain stem ? spinal
cord
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26Neural circuitry in male rats
- Medial preoptic area (MPOA)
- Major integrative site
- Has androgen and estrogen receptors
- Receives input from vomeronasal organ, medial
amygdala, and genitals - Sends output to midbrain ? brain stem ? spinal
cord - Can initiate erection, ejaculation, as can
several lower structures
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29Effects of stress on gonadal hormones
- Endorphins enkephalins shut down GnRH (LHRH)
from hypothalamus ? drastic decrease in LH FSH
from anterior pit. ? testes, ovaries close for
lunch. - Highly trained athletes reach puberty later
women have menstrual irregularities. - Same for opiate addicts.
- Too much or too little exercise can be bad.
30Effect of stress on erections
- Parasymp. system (PNS) ? blood flow to penis.
- Nitric oxide (NO) ? vasodilation
- Viagra prolongs NOs effects.
- Balance between SNS PNS
- SNS ? heart rate, breathing, getting ready for
ejaculation - PNS ? maintain erection, also moves sperm to
seminal vesicle - Finally, SNS takes over and ? ejaculation
31Effect of stress on erections
- Stress, via SNS, can either ? premature
ejaculation or lack of erection altogether. - Erectile dysfunction is a stressor in itself.
- Test psychogenic vs. physiological dysfunction
with a roll of stamps at night.
32Our friend the hyena
- Females are dominant have a penis.
33Our friend the hyena
- Females have high levels of androstenedione, an
androgen. - Made in ovaries.
- Androstenedione both masculinizes the genitals
and ? aggressiveness. - Males and subordinate females get erections to
show submission!! - Especially when they are stressed.
34Females lengthened cycles and amenorrhea
- Stress decreases conversion of adrenal androgens
to estrogen in fat tissue . - Therefore, there is less estrogen.
- Same thing if you starve voluntarily
- Anorexia nervosa ? amennorhea
- Avg. pregnancy costs 50,000 calories.
- Nursing costs 1000 calories/day
- You need some fat to provide calories.
35Females lengthened cycles and amenorrhea
- Endorphins enkephalins also decrease GnRH
release. - Prolactin glucocorticoids block pituitary
sensitivity to GnRH. - Glucocorticoids decrease sensitivity of ovaries
(and testes) to FSH LH. - Prolactin breast feeding contraceptive
- Nursing has to be frequent
36Females disruption of libido
- Both estrogen and adrenal androgens contribute to
libido. - Both are decreased by stress.
37Stress and the success of high-tech fertilization
- Artificial fertilization and in vitro
fertilization have a high failure rate. - Due, in part, to stress of the procedure.
38Miscarriage, psychogenic abortions, and preterm
labor
- Miscarriage in wild animals when new male takes
over - The male would kill the previous offspring.
- Female has odor-based mechanism that ?
miscarriage. (Bruce-Parkes effect) - However, such miscarriages in humans are rare,
unless severe and repeated activation of SNS
shuts down blood flow to uterus.
39Reproduction during extreme stress
- The amazing thing is how resistant to stress
reproduction is. - Even in Nazi death camps, almost half the women
continued to menstruate.
40Summary
- All steroids are closely related (derived from
cholesterol) P ? T ? E or DHT. - GnRH (from hypothalamus) ? ant. pit. (AP)
- FSH LH (from AP) ? ovaries or testes
- FSH stimulates follicles to produce E and nurture
ova. - FSH stimulates testes to produce sperm.
41Summary
- LH stimulates Leyden cells in male to ? T
- LH surge in females ? ovulation
- After ovulation, LH stimulates thecal cells in
corpus luteum to ? P, most of which is released
without conversion to T and E - P builds up endometrium.
42Summary
- Menstrual cycle FSH ? egg (oocyte) E
- High E ? positive feedback on GnRH ? LH surge.
- LH breaks gap junctions that have kept oocytes
from 1st meiotic division ? ovulation. - Oocyte has 2nd meiotic division only if
fertilized by a sperm. - LH also causes follicle to ? corpus luteum ? P ?
increase vascularization of endometrium. - If no fertilization high EP ? neg feedback?
decreased EP ? endometrial lining sloughs off.
43Summary
- Sexual behavior 4 components
- Attractivity
- Proceptivity
- Copulation
- Refractory period
44Summary
- Main control area for female sexual behavior is
ventromedial nucleus of hypothalamus - Main control area for male sexual behavior is
medial preoptic area, at front of hypothalamus
45Summary Stress effects on reproduction
- Endorphins enkephalins decrease GnRH from
hypothalamus - PRL decreases ant. pit. response to GnRH
- Therefore less FSH and LH
- GCs decrease responsiveness of ovaries and testes
to FSH LH - Therefore hormone production and gamete
production are impaired.
46Summary
- SNS overactivity inhibits erections
- Erections are caused by parasympathetic sys
- Nitric oxide (NO) ? vasodilation
- Viagra increases duration of NOs effects
- In females starvation or excessive exercise ?
decrease of body fat ? decrease in E production
in fat ? delays puberty, can cause amenorrhea.