Lecture 10: Sex Flashcards
gender
the characteristics and traits considered socio-culturally appropriate for men and women. the term ‘gender’ implies biological mechanisms
sexual orientation and gender identity
can be measured along a spectrum with characteristics traditionally considered more masculine or feminine
sex differences
there are both biological and sociocultural differences between genders
asexual reproduction
only requires a single parent
sexual reproduction
based on evolutionary theory, sexual reproduction must have an adaptive function. asexual reproduction would ensure the passage of harmful mutations, while sexual reproduction reduces this chance. sexual reproduction also gives rise to diversity and possibility that future generations will have an advantageous genetic combination
sex determining region of the Y chromosome (SRY)
a region on the Y chromosome that has the gene which codes for sex. the SRY is linked to a testes-determining factor (TDF), which allows male gonads to develop
female genitalia
the entire external female genitalia is called the vulva. first there is mons veneris, as area of fatty tissue with a triangle of pubic hair above it. from mons veneris, on either side of the vulva, extends to labia majora, separated by the pudendal cleft
labia minora
hairless flaps of skin that are located inside the labia majora and surround the opening of the vagina. the inside of the labia is called the vastibule and at the top, where the labia minora meet, is the clitoral hood
corpus cavernosum
the erectile tissue of the clitoral shaft consists of two corpus cavernosum, which are blood-gilled chambers
pacini’s blood cells
provides deep sensation and sensory vibration
urethral opening
the main function of the urethra is to allow urine to leave the bladder
perineum
the sensitive area between the vagina and the anus
hymen
the young girls vagina is “covered” by a membrane of the skin referred to as the hymen. the tearing of these membranes during sex has great significance in many cultures, indicating that the women is no longer a virgin
vagina
the tube that connects the uterus to the external genitalia. its function is to carry the male’s sperm to the uterus for fertilization, and it is also the route by which the offspring are taken to the outside world
three levels of the vagina
- internal mucosal layer: provides a larger surface area when extended due to the elastic fibers present and the network of blood vessels. it is transudate of these blood vessels, combined with cervical mucus, that provides vaginal fluid during sexual arousal
- intermediate muscularis layer: the muscle layer
- external adventitial layer: an elastic tissue that provides structural support and allows for expansion
cervix
at the top of the vagina there is the cervix. the cervix has an opening through which sperm can enter the uterine environment and menstrual fluid can leave the uterine environment
three layers of the uterus
- inner layer: the endometrium made of connective tissue
- middle layer: the myometrium made of smooth muscle
- outer layer: the perimetrium made of connective tissue
fallopian tube
at the top of the uterus is the fallopian tube which extends left and right. the fallopian tube delivers ova from the ovaries to the uterus. at the end of the fallopian tube is an area called the infundibulum, where fimbriae branch to catch released ova and direct them to the tube. it is the ampulla, middle part of the fallopian tube fertilization is most likely to occur
cilia
fill up the inside of the fallopian tube. hair like structures that facilitate the movement of the ovum along the tube
scrotum
contains the testicles that are visible beneath the surface of the skin
corpora cavernosa
responsible for most of the erection. around it is connective tissue and this is called tunica albuginea
corpus spongiosum
passes through the midline of the surface of the penis around the urethra
sex hormones
much of the adolescent behavior is attributed to sex hormones, which are made of cholesterol and fall into three categories
three categories of sex hormones
- androgens: such as testosterone and 5-alpha dihydrotestosterone (DHT). these are typical male sex hormones
- estrogens: such as estradiol. these are reproductive hormones
- progestins: such as progesterone. these are female sex hormones
both sexes posses androgens and estrogens, but at different concentrations
aromataste
an enzyme which helps convert testosterone into estradiol
5-alpha reductase
an enzyme that converts testosterone into DHT
conversions
- cholesterol > progesterone > testosterone
- testosterone > (aromatase) > estradiol
- testosterone > (5-alpha reductase) > DHT
secretion of testosterone
testosterone is secreted by the adrenal glands, testes and also the ovaries. the majority of testosterone is produced by the testes and this causes testosterone levels to be elevated in men
progesterone
the main female hormone
oxytocin
is a peptide hormone produced by the hypothalamus and stored and secreted by the posterior pituitary gland. the pituitary hormone causes muscle contraction, involved in breastfeeding, childbirth, and orgasm
gonadotropin-releasing hormone (GnRH)
a hypothalamic hormone that facilitates the release of the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) from the anterior lobe to the pituitary gland
FSH
promotes the maturation of gametes (ovum and sperm)
LH
promotes the secretion of androgen and is involved in the regulation of the menstrual cycle
prolactin
involved in lactation
menstrual cycle
consists of two interconnected cycles: the ovarian cycle and the endometrial cycle
ovarian cycle
is the interaction of the ovaries, hypothalamus and pituitary gland that affects the endometrial cycle, in which the endometrium undergoes changes. all about preparing and releasing the egg
endometrial cycle
about preparing the uterine lining for the potential pregnancy
phases of the menstrual cycle
- menstruation
- follicular phase
- luteal phase
menstruation
a decrease in progesterone causes menstruation, during which the endometrium breaks and is removed. the reason for this is the change in the endometrium from a state where it can support pregnancy, to one that facilitates sperm transport. estrogen levels also drop during this phase
follicular phase
estrogen levels begin to rise in the follicular phase. the hormonal changes cause a negative feedback loop between estrogens and gonadotropins and cause a decrease in GnRH. as estrogen levels decrease, LH and FSH increase. the increase in FSH promotes the follicles in the ovaries to develop. during the follicular phase, one of the follicles becomes dominant and grows faster than the other: this is known as the preovulatory follicle
luteal phase
progesterone is the main sex hormone of the luteal phase. during the luteal phase, the dominant follicle transforms into the corpus luteum which releases progesterone and estrogen. these help in maintaining pregnancy with the fertilized egg. during this phase, the endometrium of the uterus thickens due to progesterone. at the end of the lutela phase, the corpus luteum begins to deteriorate and the levels of progesterone and estrogen decrease
ovulation
during the cycle, the important event is ovulation, where an egg cell is released from one of the ovaries. ovulation is the point in the cycle when a women is most fertile
premenstrual syndrome
when women feel relaxed during ovulation due to an increase in oestrogen. however during the luteal phase, these women do not feel good: oestrogen and progesterone levels drop and this causes anger, irritation and sadness
menopause
there is a decrease in the production of estrogen, there are low levels of testosterone and thinner vaginal walls. symptoms include decreased libido, hot flashes and sweating
premenstrual dysphoria disorder (PMDD)
symptoms are PMDD are:
- feeling of helplessness or thoughts of suicide
- tension or anxiety
- panic attacks
- mood swings
- persistent irritability or anger
- lack of interest in daily activities
wolffian duct
is in contact with the gonads. will later develop into the sperm duct
mullerian duct
runs alongside the gonads, but without contact. will later develop into the fallopian tube, the uterus and the inner part of the vagina
development into a man
to develop into a women, nothing needs to happen. however, to develop into a man, the testes secrete an anti-mullerian hormone. this binds to receptors in the ducts and causes them to disappear early in development
virilization or masculinization
the biological development of sex differences. the changes are caused by androgens (male hormones)
food intake
women with higher education experience their menstruation earlier: they have more money available to consume adequate food. animal based food intake is related to earlier sexual development and plant based protein intake is related to later maturation
androgen insensitivity syndrome
when the person has XY chromosomes, but they are phenotypically women. due to the lack in functional androgen receptors and without them, their bodies cannot respond to testosterone. the external genitalia are female, but their internal female organs have not been able to develop because AMH is still active
persistent mullerian duct syndrome
a condition caused by an inborn deficiency of AMH or its receptors. in men, it causes the development of both male and female internal genitalia
polycystic ovarian syndrome (PCOS)
a condition characterized by disruption of the ovulation cycle due to cysts around the edge of the ovaries and excessive secretion of androgens, resulting in hyperandrogegism. have higher levels of testosterone, irregular periods, more facial hair and problems with reproduction. furthermore, the ovaries look like cysts
turner syndrome
there is only one X chromosome (X0). such people develop female genitalia and external genitals, but often do not have ovaries. without the help of estrogen pills, they do not reach puberty and sexual maturation
congenital adrenal hyperplasia
a defect of the adrenal glands in which they are overexcited, causing testosterone to enter the bloodstream. the effect of testosterone is to masculinize, so a female fetus exposed to androgens has an enlarged clitoris and fused labia. exposure to excessive androgens in a male fetus results in early virilization, enlarged penis and an increase in body hair
klinefelter syndrome
a genetic disorder in which there are two X chromosomes and one Y chromosome (XXY). characteristics on klinefelter syndrome include small testes, reduced facial hair, gynecomastia, erectile dysfunction, infertility, and cognitive deficits
organization-activation hypothesis
became the dominant theory of sex differences in the brain. here, the organization is the influence of sex hormones on the developing brain and activation effects are reversible and depend on hormone levels in the adult brain
binary
gender is conceptualized as binary: there are two forms, male or female
hypothalamus
the main area of difference between male and female brain, specifically pre optic nucleus. because the difference between the male (larger) and female (smaller) hypothalamus were clearly identifiable, this area become known as the sexual; dimorphic nucleus (SDN)
excitement phase (1)
during the arousal phase in women, the labia minora become deeper in color and open, the fluid in the vagina increases, and the clitoris and breast nipples become stiff. in addition the heart rate and blood pressure increase. in men, the arousal phase is characterized by the erection of the penis. this is due to decrease in sympathetic activity and an increase in parasympathetic activity
plateau phase (2)
this phase is a state of high excitability that can be maintained for variable period of time. during the plateau phase, the gland of the clitoris disappear under the hood and the outer part of the vagina becomes tighter. in men, the erection becomes stronger and the bulbourethral gland secrete their clear sticky substance: pre-cum
orgasm phase (3)
orgasm is usually felt as a brief succession of muscle contraction and the subjective experience of the release of sexual tension. in men, just before ejaculation, sperm is secreted into the posterior part of the urethra. convulsions of the smooth muscles in the urethral wall and the muscles of the penis are responsible for ejaculation
resolution phase (4)
the resolution phase is when arousal subsides and the body relaxes again. men have insensitive period when further stimulation does not lead to erection or orgasm. dopamine is linked to sexual behavior
sexual orientation
studying the brains of homosexual and heterosexual men revealed differences in the interstitial nucleus of the anterior hypothalamus. this area of the hypothalamus was found to be smaller in homosexual men and heterosexual women than in heterosexual men
female genital mutilation (FGM)
refers to the partial or complete removal of external female genitalia for non-medical reason. can lead to problems with urination, cysts and complication during childbirth. is common in africa, middle east and asia, related to beauty ideals
gynodiversity
means that women come in all forms: sometimes women have surgery on their genitals, this is called gynoplasty
labiaplasty
plastic surgery to change the labia minora (inner labia) and labia majora (outer labia), the folds of skin around the vulva
brain of transgender
the brain of someone in transition is much more like the brain of the gender they are transitioning to than the biological brain they were born with
genotype vs phenotype
