Exam 2 Flashcards
What was William C. Young’s hypothesis?
Activational effects can vary person to person based on how the brain was organized with development hormones.
How are males and females sexually dimorphic for their pattern of HPG axis activity?
Males: have “tonic” activity (fairly steady levels of activity)
Females: have “phasic” activity (cyclical activity)
What is a follicle?
A Follicle is a sphere of granulosa cells surrounding the oocyte (egg). As the follicle matures, it becomes surrounded by an outer layer of cells called the theca cells.
What is a primordial follicle?
A single layer of granulosa cells surrounding ovum.
What is a zona pellucida?
Ovum develops an outer layer of glycoproteins that eventually binds sperm.
What is a secondary follicle?
Several layers of granulosa cells surrounded by a single layer of theca cells
What is a tertiary follicle?
Granulosa cells secrete fluid that accumulates within the follicle; theca differentiates into theca interna and theca externa layers
What is an antrum?
space between the oocyte and the outer wall of the follicle
What is liquor folliculi?
Juice in the antrum; rich in estrogens
What is a Graafian follicle?
During each cycle usually only 1 follicle becomes mature, the other 19 tertiary follicles die off.
When does ovulation occur?
Ovulation occurs when the graffian follicle ruptures, propelling the ovum towards the mouth of the fallopian tubes
What are the steps of estrogen and progesterone production in the ovary?
- LH stimulates theca interna to produce testosterone
- Testosterone diffuses out of theca interna cells and diffuses into granulosa cells.
- FSH stimulates granulosa cells to produce an enzyme - aromatase
- Aromatase converts testosterone to estradiol in granulosa cells.
- After ovulation, LH stimulates granulosa cells to produce progesterone and estrogen.
What is the menstrual phase? When does it occur?
Day 1-5.
Sloughing off of uterine lining; bleeding due to exposure of corkscrew blood vessel endings.
Very low progesterone & estrogen; LH & FSH increase by day 5
What is the follicular phase? When does it occur?
Days 6-12.
Development of follicles and mature egg.
Steady increase in estrogen, progesterone remains low.
What is the luteal phase? When does it occur?
Days. 15-21.
Preparation of uterus to receive fertilized eggs (pseudopregnancy in the absence of fertilization).
Estrogen after temporary dip returns to high levels, progesterone rises to high levels.
What is the corpus luteum?
Graafian follicle collapses and the granulosa and thecal cells become corpus luteum; produces progesterone and estradiol
What happens during 22-28 of the ovulation cycle?
In Absence of fertilized egg the luteal phase winds down; estrogen and progesterone levels decline. Withdrawal of progesterone from uterus triggers menstruation.
What is the corpus albicans?
The dying remnant of corpus luteal tissue.
What oral contraceptive pills are taken on days 22-28?
Placebo pills; absence of progesterone allows for menstruation
What is the mechanism of action of hormonal birth control?
Essentially “lock” the cycle into the luteal phase, thereby preventing follicle maturation and ovulation. Progesterone is the hormone that is only present after ovulation so its constant presence will prevent the follicular phase and maturation.
Progesterone in oral contraceptives prevents an LH surge by…
Maintaining high negative feedback on LH secretion
What is Plan B?
Plan B is a high dose of synthetic progesterone intended to suppress ovulation. It may also interfere with the ability of sperm to migrate into the fallopian tubes by thickening the cervical mucous.
What is RU486?
A synthetic progesterone receptor antagonist intended to cause miscarriage by inducing menstruation.
What is the negative feedback loop of HPG axis?
In response to low levels or estrogens and progesterone, GnRH and LH & FSH levels decrease.
What is the positive feedback loop of the HPG axis?
High levels of estrogen will trigger a GnRH surge, which in turn triggers an LH surge.
What causes a shift from negative feedback to positive feedback?
Negative feedback shifts to positive feedback after a threshold of estrogen exposure has been surpassed.
Where is the surge center?
Hypothalamus - anteroventral periventricular portion of the pre-optic area and suprachiasmatic nucleus.
What is the outcome of this experimental manipulation [2]?
Ovulation
What is the outcome of this experimental manipulation [3]?
No Ovulation
What is the outcome of this experimental manipulation [4]?
No Ovulation
What does the enzyme aromatase do?
Converts androgen to estrogens
What is the outcome of this experimental manipulation [5]?
Ovulation, testosterone cannot be converted to estradiol so the male rat develops functional surge center.
The ability of the adult rat to respond to estrogen positive feedback is an example of…?
Organizational effect
Both male and female fetuses are exposed to high levels of estrogen from their moms, if estrogen has a masculizing effect on the developing brain, why aren’t female brains masculinzed?
Alpha-fetal protein is a carrier protein secreted by the fetal liver that binds estradiol so strongly that it can’t cross the blood brain barrier.
What is the expected outcome to testing a female with high levels of estrogen?
A female organized brain will show an increase in LH levels.
What was the first report of an anatomical dimorphism?
A region of the medial pre-optic area (MPOA) showed a different pattern of synaptic connections, females had more synapses on dendritic spines (excitatory) and males had more synapses on dendritic shafts (inhibitory).
What is lateralization of brain function?
Difference in function between the two hemispheres.
How is the corpus callosum different between females and males?
Posterior corpus callosum larger in women.
How is the anterior commissure different between females and males?
Larger cross-sectional diameter in women
Is there evidence for distinct female vs. male organized brains in terms or structure and function?
No, there are some aspects of brain structure/function that on the average are sexually dimorphic but every brain has a combination of these features.
What is the difference in olfaction perception between men and women? When does this difference develop?
Women are ~1,000 times more sensitive to musk-like odors than men. This difference develops after puberty.
What are ways to determine if a difference is a result of activational effects of gonadal steroids?
-Do sex differences emerge after puberty?
-Does the function vary before, during, and after pregnancy?
-Does the function vary across the menstrual cycle?
-Do sex differences diminish after menopause?
What is the difference in taste perception between men and women? What is the evidence for hormonal influences?
Women are more sensitive, especially to bitter taste.
-Sensitivity increases after puberty, sensitivity increases during the follicular phase, and during pregnancy, but diminishes after menopause.
What is the difference in audition perception between men and women?
Women have better detection threshold for pure tones and less tolerance for white noise.
What is the difference in vision perception between men and women?
Men have better visual acuity, women tolerate higher levels of light intensity and dark adapt more quickly
What is the difference in pain perception between men and women?
Women have better pain sensitivity
What is the difference in cognitive function between men and women?
Women excel at verbal tasks, perceptual skills and fine motor skills.
Males excel on quantitative tasks and visuospatial ability.
Is there evidence for activational effects of hormones on sexual orientation and gender identity?
No, there is no evidence for differences in circulating gonadal steroid hormone levels in individuals of the same sex that depends on sexual orientation or gender identity.
What is male rat behavior dependent on?
Male mating behavior in rats is dependent on activating effects of androgens present during adulthood.
What is the outcome of this experimental manipulation [1]?
No mating behavior
What is the outcome of this experimental manipulation [2]?
Mating behavior resumes
What is the outcome of this experimental manipulation [3]?
Mating behavior resumes
What is the outcome of this experimental manipulation [4]? Why?
Mating behavior does not resume because DHT cannot be converted to estrogen.
What is required for mating behavior in the adult male rat?
It requires the conversion of testosterone to estradiol
What is absolutely necessary for male rat mating behavior?
Estrogen receptor activation
What is the outcome of this experimental manipulation [5]?
Female Pattern Mating Behavior
Does the ability to express a male pattern of mating behavior in the rat depend on an organizational or activational effect of hormones?
An organizational effect of hormones
What are the 4 brain components that best characterize the neuroanatomy of male mating behavior?
- medial preoptic area
- olfactory system
- amygdala
- bed nucleus stria terminalis
What is pheromone signaling an example of?
Ectocrine signaling
What is the Flehman response?
A characteristic behavior of many animals that facilitates placement of pheromones from tongue to opening in roof of mouth leading to vomeronasal organ
What was the result of a MPOA lesion?
Impaired preformance
What was the result of a basolateral amygdala lesion?
Impaired drive
What was the result of castration?
Impaired drive and impaired performance
How does dopamine effect male mating behavior?
Dopamine agonists increase mating, dopamine antagonists decrease mating
What is the result of daily treatment of men with GnRH receptor agonist?
Decrease testosterone production by promoting down regulation of GnRH receptors
What did Robert Sapolsky find?
Young males with high testosterone became dominant males
What is estrus?
time of sexual receptivity in females
What is the attractivity stage of mating behavior in females?
Male rate and male primates perfer being with female around her time of ovulation
What is the proceptivity stage of mating behavior in females?
Drive, flirting and courtship
What is the evidence for hormonal influence on mate preference in humans?
One study found that women preferred the scent of symmetrical men during the time of ovulation than at other points in their menstrual cycle
What is the receptivity stage of mating behavior in females?
Performance
What determines whether the pattern of behavior will be male or female?
Organizational events at birth, whether or not the brain during development was exposed to estrogen
In the adult rat, mating behavior requires…?
The local presence of estradiol in the brain of an adult
What is the role of NT in female sexual behavior?
Norepinephrine: facilitate performance
Dopamine: facilitate proceptive behaviors
Serotonin: inhibit sexual behavior
Endorphins: Opiate agonists inhibit sexual behavior
What is the Lee-Boot effect?
Female mice housed together lengthens time of ovulatory cycle because there is no mating so the luteal phase is skipped.
What is the whitten effect?
Large number of female mice housed together in absence of male show extreme interruptions in estrous cycles.
What is the Bruce effect?
Placing pregnant females with strange male resulted in termination of the pregnancy and subsequent mating with the new male
What is the Vandenbergh effect?
Females housed with adult males attain puberty sooner and females housed with other males attain puberty later
What were the results of the new McClintock study?
-Exposure to follicular phase secretions decreased the length of recipient’s menstrual cycle
- Exposure to ovulatory phase secretions increased the length of recipient’s menstrual cycle
