hormones and sex (3.4)

Question 1

sexual differentiation in mammals

Answer 1

begins at fertilization with the production of two different zygotes (XY male; XX female)

Question 2

sex chromosomes

Answer 2

contain the genetic programs that direct sexual development

Question 3

steroid hormones (definition and types (3))

Answer 3

definition: the hormones that influence sexual development and behavior
types: androgens (testosterone), estrogens (estradiol), proestogens

Question 4

synthesizes steroid hormones

Answer 4

cholesterol

Question 5

how steroid hormones exert their effects (3)

Answer 5

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

Question 6

gonads

Answer 6

the primary organs that release sex hormones (male testes, female ovaries)

Question 7

regulates endocrine organs

Answer 7

signals from the nervous system (hypothalamus and pituitary)

Question 8

periventricular nucleus (PN)

Answer 8

regulates the release of sex hormones from the gonads (hypothalamus via anterior pituitary)

Question 9

gonadotropin releasing hormones (GnRH)

Answer 9

secreted into the portal system by cells scattered in the PN

Question 10

gonadotropins released from anterior pituitary (2)

Answer 10

follicle-stimulating hormone (FSH), luteinizing hormone (LH)

Question 11

signals that regulate sex hormone release (2)

Answer 11

from CNS (reticular formation (locus coeruleus) and limbic system decisions); from circulating hormones

Question 12

detectors (arcuate nucleus vs anteroventral PN)

Answer 12

arcuate nucleus: negative feedback = stabilized levels, male
anteroventral PN: positive feedback = surge, female

Question 13

kisspeptin (KISS)

Answer 13

the hormone that detectors use to activate the GnRH neurons

Question 14

development (cortex vs medulla)

Answer 14

cortex: potential to be an ovary
medulla: potential to be a testis

Question 15

SRY protein

Answer 15

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)

Question 16

Wolffian system vs Müllerian system

Answer 16

Wolffian: male; seminal vesicles, vas deferens
Müllerian system: female; uterus, vagina, fallopian tubes

Question 17

testes

Answer 17

produce testosterone and Müllerian-inhibiting substance

Question 18

genitalia

Answer 18

external reproductive structures that develop from one bipotential precursor

Question 19

parts of bipotential precursor (4)

Answer 19

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

Question 20

puberty

Answer 20

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)

Question 21

genotype (6)

Answer 21

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)

Question 22

adrengenital syndrome (AS) vs androgen insensitivity syndrome (CAIS)/no androgen receptors (no-AR)

Answer 22

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)

Question 23

anabolic steroids

Answer 23

upping the levels of hormones; will become infertile

Question 24

male vs female behavior

Answer 24

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

Question 25

brain mechanisms of sexual behavior (4)

Answer 25

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

Question 26

oxytocin

Answer 26

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)

Question 27

gender and orientation

Answer 27

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)

Question 28

influencing factors of orientation (3)

Answer 28

genetics, hormones (levels of organizational testosterone -> low in males, high in females = homosexuality), social (observation and imitation)