hormones and sex (3.4) Flashcards
sexual differentiation in mammals
begins at fertilization with the production of two different zygotes (XY male; XX female)
sex chromosomes
contain the genetic programs that direct sexual development
steroid hormones (definition and types (3))
definition: the hormones that influence sexual development and behavior
types: androgens (testosterone), estrogens (estradiol), proestogens
synthesizes steroid hormones
cholesterol
how steroid hormones exert their effects (3)
1) binding to a metabotropic receptor
2) entering the cell and binding/activating receptors in the cytosol
3) entering the nucleus and activating receptors that bind to chromosomes, where they activate/inactivate genes
gonads
the primary organs that release sex hormones (male testes, female ovaries)
regulates endocrine organs
signals from the nervous system (hypothalamus and pituitary)
periventricular nucleus (PN)
regulates the release of sex hormones from the gonads (hypothalamus via anterior pituitary)
gonadotropin releasing hormones (GnRH)
secreted into the portal system by cells scattered in the PN
gonadotropins released from anterior pituitary (2)
follicle-stimulating hormone (FSH), luteinizing hormone (LH)
signals that regulate sex hormone release (2)
from CNS (reticular formation (locus coeruleus) and limbic system decisions); from circulating hormones
detectors (arcuate nucleus vs anteroventral PN)
arcuate nucleus: negative feedback = stabilized levels, male
anteroventral PN: positive feedback = surge, female
kisspeptin (KISS)
the hormone that detectors use to activate the GnRH neurons
development (cortex vs medulla)
cortex: potential to be an ovary
medulla: potential to be a testis
SRY protein
synthesis triggered by the SRY gene on the Y chromosome in the seventh week after conception; causes the medulla to grow into a testis (absence = cortex expands and develops into an ovary)
Wolffian system vs Müllerian system
Wolffian: male; seminal vesicles, vas deferens
Müllerian system: female; uterus, vagina, fallopian tubes
testes
produce testosterone and Müllerian-inhibiting substance
genitalia
external reproductive structures that develop from one bipotential precursor
parts of bipotential precursor (4)
glans: head of penis or clitoris
urethral folds: fuse or enlarge (labia minora)
lateral bodies: shaft of penis or hood of clitoris
labioscrotal swellings: scrotum or labia majora
puberty
the transitional period between childhood and adulthood; associated with an increase in the release of hormones (growth and sex tropic) by the anterior pituitary (under control of PN in hypothalamus); fertility is achieved and secondary sex characteristics develop (more androgens or estrogens)
genotype (6)
XX: vast majority of females
XY: vast majority of males
XXX: largely indistinguishable from XX
XYY: largely indistinguishable from XY
XO: likely to become infertile; female phenotype
XXY: teste that puts out just as much testosterone as it does estrogen (intersex)
adrengenital syndrome (AS) vs androgen insensitivity syndrome (CAIS)/no androgen receptors (no-AR)
AS: over-release of androgens in XX females by the adrenals; ovaries and Wolffian ducts with no anti-Müllerian hormone
CAIS/no-AR (two scenarios): (1) Y chromosome but nonworking SRY gene (will have ovaries); (2) testosterone released but cells do not detect it (external female genitalia but no internal plumbing)
anabolic steroids
upping the levels of hormones; will become infertile
male vs female behavior
male: loss of testes leads to reduced sexual interest and behavior; male sexuality NOT correlated with testosterone levels in healthy men
female: surges of sex hormones initiate estrus (period of fertility and receptivity); sexual motivation and behavior not tied strictly to menstrual cycle but do peak about ovulation; sex drive may be under androgenic control
brain mechanisms of sexual behavior (4)
cortex (love): complex emotion of the aspect of sexual experience
ventral striatum (libido): sex drive; effects reward circuit; effected by testosterone; needed for survival (i.e. anticipation)
hypothalamus (labor): medial preoptic and ventromedial nucleus (see earlier notes)
amygdala (likes): [sexual] preference center
oxytocin
produced by the paraventricular nucleus of the hypothalamus and released central and peripherally (by posterior pituitary); plays a role in all aspects of sexual behavior (pair-bonding, cuddle, love hormone)
gender and orientation
gender: the concept of self as male or female, or a blend of both or neither (may be different than anatomical sex)
orientation: an enduring pattern of romantic or sexual attraction to persons of the opposite sex/gender (heterosexuality), the same sex/gender (homosexuality), or both sexes/multiple genders (bisexuality) (asexuality = lack of sexual attraction)
influencing factors of orientation (3)
genetics, hormones (levels of organizational testosterone -> low in males, high in females = homosexuality), social (observation and imitation)
