Sex Flashcards
Gametes
Mature reproductive cells made by gonads (ovaries or testes). They are either ova (egg cells produced by ovaries) or sperm (produced by testes.
Unlike all other cells in your body, which typically have 23 pairs of chromosomes (23 from your biological mother and 23 from your biological father), gametes only have one copy of each _____ (a mix from your mother and father).
Chromosomes
One pair of chromosomes are called the ___ chromosomes, as they usually determine the organism’s sex. They come in X and Y varieties.
Sex
Five factors present at birth typically used to determine an animal’s biological sex
- Sex chromosomes: XX or XY
- Gonads: testes or ovaries (internal, but develop with separate signaling cascade)
- Sex hormones: androgen signaling
- Internal reproductive anatomy
- External anatomy
3 categories of sex organs
Gonads, internal reproductive anatomy, external anatomy
Atypical combinations give rise to ____ conditions, in which the person cannot be distinctly identified as male or female.
Intersex
True or false : All embryos contain precursors for both female and male sex organs.
True
Undifferentiated gonads
Embryonic precursor of ovaries/testes.
Müllerian system
Embryonic precursors of female internal sex organs
Wolffian system
Embryonic precursors of male internal sex organs
True or false : both of the Mullerian and Wolffian systems are present in all embryos.
True
During the ____ month of gestation, the undifferentiated gonads typically develop into ovaries or testes. They will start releasing hormones
2nd
During the ____ month of gestation, typically either the Müllerian or Wolffian system develops while the other withers away based on the released hormones starting from the 2nd month.
3rd
The SRY gene is normally located on the _chromosome
Y
SRY gene encodes a protein that causes undifferentiated fetal gonads to develop into ____.
Testes
If the SRY gene is present, it is _____over XX instructions
Dominant (XXY individuals develop testes)
Defeminization : At 2nd month, embryonic testicular release of _____ hormone
Anti-mullerian
What prevents female Mullerian system from developping ?
Anti-mullerian release from testes
Masculinization
Effect of androgen hormones early in development, which triggers development of male-typical anatomy (wolffian system).
Androgen
male sex hormone.
Testosterone
Principal mammalian androgen. I
It is released by the testes, and it triggers development of the Wolffian system (internal male sex anatomy).
Testosterone
Some testosterone is converted into ________, which is what triggers development of external male sex anatomy.
Dihydrotestosterone
XX chromosomes develops functional ____
Ovaries
Developed ovaries are largely silent until _____.
Puberty
True or false : ovaries do NOT release molecules in the embryo
True
In the absence of _______ signaling, the Mullerian system develops into internal female reproductive anatomy, which includes the inner vagina, uterus, and fallopian tubes.
Anti-Mullerian
In the absence of testosterone signaling, external female sex organs (vulva) develop while the _____ system withers away
Wolffian
Puberty is triggered by _____ released from gonads (for both testes and ovaries in male and female).
Hormones
Turner Syndrome
When you only have one sex chromosome (X-). Born with only 45 chromosomes, no functional ovaries nor testes. You have external female sex organ.
Swyer Syndrome
XY but have a bad SRY gene, female external organs develop. No gonads.
What happens when you have no gonads ?
People without gonads are infertile. They also do not naturally experience puberty, but that is easy to artificially induce with hormone injections.
It is possible to have two (or more) X chromosomes as well as the SRY gene (e.g., XXY or XXXY). This usually results in typical ….
male development patterns (but also infertility).
Insufficient anti-Müllerian hormone
Will cause insufficient anatomical defeminization: both male and female internal sex organs will develop and get tangled together. There is often functional external male genitalia.
Androgen insensitivity syndrome
Anatomical defeminization with partial or no masculinization. In severe cases, no internal sex organs develop. In these cases, people typically develop normal external female genitalia and identify as heterosexual women, but they will be infertile and have a short vagina.
Organizational effects of sex hormones
Sex hormones influence the development of the body and brain. These effects are permanent and put you on a particular trajectory going forward.
2 types of organizational effects of sex hormones
- Behavioral defeminization
- Behavioral masculinization
Behavioral defeminization :
Refers to organizational effect of androgens on the brain that prevent animals from displaying female-typical behaviors in adulthood
Behavioral demasculinization
Refers to organizational effect of androgens on the brain that enables animals to engage in male-typical behaviors in adulthood
Activational effects of sex hormones
Puberty causes sex hormones to be released by the gonads, which influence both body and mind (secondary characteristic sex characteristics).
Examples of activational effects
Production of sperm, ovulation, and general horniness
Kisspeptin, a ____ produced in the hypothalamus, initiates puberty.
Neuropeptide
Kisspeptin maintains reproductive ability by triggering the release of _____ hormone
Gonadotropin-releasing (GnRH) hormone.
GnRH stimulates ____ _____ gland to secrete ______ hormones
Anterior pituitary gland to secrete gonadotropic hormones
Gonadotropic hormones of the pituitary gland (follicle-stimulating hormone, FSH, and luteinizing hormone, LH) have stimulating effect on cells of _____.
Gonads
Testes respond to gonadotropic hormones by releasing _____ for the rest of the animal’s life. Ovaries will release _____, which controls the menstrual cycle.
Testosterone and estradiol
Without testosterone, sperm production ____, and sooner or later, so does the ability to have ___.
Ceases, sex
A castrated male rat will cease sexual activity, but it can be reinstated with an injection of ______.
Testosterone
Men taking a ______-releasing hormone antagonist will not show testicular release of androgens and have a decrease in sexual interest and intercourse, decrease in sperm production.
Gonadotropin
______ is a class of sex hormones released by the ovaries that cause maturation of the physical features and characteristic of females, such as growth of breast tissue and female genitalia
Estrogen
_____ is the principal estrogen of many mammals, including humans, which starts getting released during puberty.
Estradiol
Both menstrual and estrous cycles are controlled by the two ovarian hormones _____ and ______
Estradiol and progesterone
Female reproductive cycle of most mammals (other than most primates)
Estrous cycle
Females that have estrous cycles do not menstruate; they reabsorb their ______.
Endometrium
Most female mammals are typically only sexually active during the _____ phase of their cycle, which is referred to as being “in heat”. This change in physiology and behavior alters the behavior of nearby males.
Estruous
However, the organizational effects of hormones on the brain continues for a few weeks after birth in ______.
Rodents
We can masculinize or feminize the brain of rodents by altering _____ signaling immediately after birth, after the anatomical development of their sex organs is complete.
Hormone
When male rodents are castrated at birth, it stops further _____ signaling, and they develop some female-typical behaviours.
Androgen
If castrated male rodents are injected with female sex hormones in adulthood (estradiol and progesterone), they will try to get ____males/females to have sex with them
Males
Injections of ____ sex hormones in non-castrated male rats (or males castrated in adulthood) have relatively small behavioural consequences
Female
Injecting testosterone in adulthood has no impact on female and male rats if not given testosterone after _____.
Birth
Injecting a nonandrogenized (did not receive testosterone before) female rat with female sex hormones in adulthood will activate…
sexual behavior
Injecting testosterone at birth in female rats then giving them the female sex hormones in adulthood won’t produce …
Sexual behavior (defeminization).
Injecting testosterone at birth in male rats then injecting testosterone in adulthood will …
cause sexual behavior (masculinization).
Human ____ glands, which are present in men and women, typically secrete a small amount of androgens.
Adrenal
Some people’s adrenal glands secrete abnormally large amounts of androgens, which can start either before or after birth. If the condition is present at birth, it is called…
Congenital adrenal hyperplasia (CAH).
In males, excess androgen signaling from adrenal glands has minimal effect, since…
their testes already secrete tons of androgens.
in females, excess androgen signaling can cause some degree of ______ of either the body or brain or both.
Masculinization
For women, depending on the amount of ______ signaling during development, sex organs can become slightly masculinized (e.g., enlarged clitoris, partially fused labia). Brain anatomy and function can also be masculinized.
Androgen
By injecting transneuronal _____ tracer in muscles responsible for lordosis response in female rats, researchers identified the important neural pathways.
Retrograde
Pathway of female sexual behavior
VMH → PAG (midbrain) → nPGi (medulla) → motor neurons in spinal cord
Ventromedial nucleus of hypothalamus (VMH)
Large nucleus in the hypothalamus that plays an essential role in female sexual behavior.
In rodents, electrical stimulation of VMH facilitates female ____ behavior.
Sexual
Injections of estradiol and progesterone directly into VMH also stimulates sexual behavior, even in females whose ____ have been removed.
Ovaries
Female with bilateral lesions of VMH will not display _____, even if she is treated with estradiol and progesterone
Lordosis
Collection of neurons are more large in males in _____(sexually dimorphic nucleus, SDN)
Hypothalamus
Male sexual pathway
mPOA → PAG → nPGi → motor neurons in spinal cord
Medial Preoptic Area (mPOA)
Nucleus in the anterior hypothalamus that plays essential role in male sexual behavior.
Electrical stimulation of mPOA in rodents elicits…
Male copulatory behavior.
Lesioning the mPOA of female rats does not affect their ___ ____, but it does cause them to ignore their offspring.
Sexual behavior
Androgenized females (ex. females with CAH) that were given testosterone immediately after birth will have an identical ___ to males.
SDN
In approximately __ percent of mammalian species, sexually mature couples tend to form long-lasting, fairly monogamous pair bonds.
5
The formation of pair bonds seems to relate to two peptides in brain:
vasopressin and oxytocin.
Equivalent to hormones in the brain
Neuropeptides
Levels of the pair bond hormones are elevated during…
Sex, childbirth, and breastfeeding.
The prairie vole species that form long term pair bonds have more vasopressin and oxytocin receptors in their ___ _____ than other species do.
Ventral forebrain
Pharmacologically blocking or activating pair bond neuropeptides receptors influences…
who they pair up with and when.
Artificially increasing the expression of pair bond receptors in non-monogamous prairie vole brains causes them to …
form life-long, monogamous-ish pair bonds.
