Chapter 17: Sex and the Brain Flashcards
life- maintaining functions:
1. regulated by ()
2. conscious control by ()
- subcortical structures
- cerebral cortex
() -> the biological state of being male or female; physical characteristics at birth
sex
factors that determine a person’s sex
chromosomes, hormones, and body anatomy
() -> set of behaviors and attributes a culture associates with men and women; socially constructed
gender
() diseases occur more often in men than women
X-linked
(): gene of Y chromosome; sex-determining region
SRY
SRY on the Y chromosome encodes for (1) -> causes development of (2)
- testis-determining factor
- testes and testicular hormones (male development)
extra X chromosome in a male (e.. XXY); no or mild symptoms, but patients have low testosterone
Klinefelter syndrome
partial or complete absence of 1 X chromosome (XO genotype)
Turner syndrome
first 6 weeks of pregnancy -> sexually undifferentiated:
- () becomes the oviduct
- () becomes the vas deferens
- Müllerian duct
- Wolffian duct
SRY -> testosterone -> development of Wolffian duct due to expression of ()
Müllerian-inhibiting factor -> inhibits formation of Müllerian duct
condition of having both male and female reproductive organs
hermaphroditism
() regulate the development and function of the reproductive system and sexual behavior
sex hormones
() release sex hormones
endocrine glands (ovary and testis)
() regulates endocrine glands
pituitary gland
male hormone (1): testosterone
female hormone (2): estradiol
- androgen
- estrogen
testosterone + () -> estradiol
aromatase
() hormones pass through cell membranes and bind to cytoplasmic receptors to regulate gene expression
steroid
describe levels of male testosterone throughout the day
fluctuate rapidly each day -> correlate with anger, conflict, etc
in females, ovaries secrete estradiol (estrogen) and ()
progesterone (progestin)
describe how female sex hormone level vary
fluctuate in a 28-day cycle
(1) -> released by the anterior pituitary; release is promoted by hypothalamic (2)
- gonadotropins (LH, FSH)
- gonadotropin-releasing hormone (GnRH)
in males, (1) stimulates testosterone production, while (2) aids in sperm maturation
- luteinizing hormone (LH)
- follicle-stimulating hormone (FSH)
in females, () cause estrogen secretion
LH and FSH
phases of the menstrual cycle
follicular, luteal
seasonal variations in reproductive behavior in some animals are controlled by variations in () -> offspring are born during the best season for survival
light levels (light -> low melatonin -> high GnRH release)
how is melatonin related to GnRH release
melatonin inhibits GnRH release
oocytes are arrested during mitosis; small number completes mitosis during () -> mature into egg cell
luteal
sexual response cycle
arousal, plateau, orgasm, resolution
arousal can occur via ()
erotic psychological, sensory stimuli, and/or tactile stimulation of genitals
() integrates cerebral activity (erotic thoughts) with sensory info from genitals -> generates output mediating sexual responses of genitals
spinal cord
the ff neurotransmitters cause relaxation of smooth muscle cells in genitalia -> engorgement of genitalia (clitoris, labia, penis) and secretion of lubricating fluids
ACh, vasoactive intestinal polypeptide (VIP), nitric oxide (NO)
viagra enhances the effect of ()
NO
() is needed to complete the sexual response cycle -> triggered by sensory neuron activity and neural input
sympathetic activity -> muscle contraction
() - male mates with many females -> common among mammals
polygyny
() - female mates with many males -> very rare among vertebrates
polyandry
() - male and female mate exclusively (3% mammals, 12 % primates, 90% birds)
monogamy
(): model for studying reproductive behavior because closely related species show very different mating strategies
voles
() voles -> social and monogamous; both parents cooperate for long-term care of young
prairie
() voles -> asocial and promiscuous; only females care for offspring briefly
montane
2 neurohormones released by posterior pituitary
- oxytocin
- vasopressin (ADH)
neurohormone released by post. pituitary; released during lactation, social boding (“love hormone”), promotes uterine contraction
oxytocin
role of oxytocin and ADH in parenting behaviors of (prairie) voles
- ADH increases paternal behaviors in males
- oxytocin increases maternal behaviors in females
human plasma oxytocin levels increase during ()
1, breastfeeding in mothers
2. sexual intercourse
how does brain activation demonstrate strong reinforcing nature of partner and parental relationship
activated brain regions when interacting with child or partner are part of reward circuitry
Male and female brains must be different -> ()
sexual dimorphism
reasons why there must be sexual dimorphisms in human brains
- differing behaviors related to sexual reproduction
- sex-specific body parts need sex-specific neural systems
- somatosensory and motor maps must adjust to varying body size and shape
examples of sexual dimorphisms of the human CNS
- Onuf’s nucleus
- INAH-1 to INAH-3 (interstitial nuclei of the anterior HT)
motor neuron pool in the spinal cord controlling bulbocavernosus muscles surrounding the base of the penis (opening of vagina in women): more neurons in men
Onuf’s nucleus
may be human analog of rat SDN
INAH-1
in the preoptic area, study found that () was 2x larger in men than women
INAH-2
(): the most distinct sexual dimorphisms in the mammalian brain (role in reproductive behavior)
Preoptic area of anterior hypothalamus
Lesions in Preoptic area of anterior hypothalamus : disrupt (1) in females and reduce (2) in males
- estrous cycle
- copulation frequency
() in rats -> obvious difference between male and female brains; bigger in males
sexually dimorphic nucleus
possible evolutionary explanations for cognitive dimorphisms
- Men: hunters: better at spatial navigation
- Women: care for children at home: more social & verbal
one major difficulty in assessing sexual dimorphisms is the fact that there are () between individuals than between sexes
larger differences (variances)
possible role of hormonal differences in sexual dimorphisms
- spatial reasoning in women is better with low estrogen
- spatial reasoning in men improves with testosterone level
2 kinds of effects of sex hormones
- organizational effects
- activational effects
describe the organizational effects of sex hormones
- permanent
- arranging tissues (anatomy) during development
describe the activational effects of sex hormones
- temporary
- drive changes in behavior
because steroids can cross the cell membrane, they can effectively bind to (1) and induce ()
- receptors on the cytoplasm and nucleus
- induce changes in gene expression level
() in fetal blood binds estrogens and protects female fetus from masculinization
α-Fetoprotein
() involved in the synthesis of
prostaglandin
Cyclooxygenase (COX)
defective androgen
receptor gene on X chromosome ()
androgen insensitivity
() in genetic females: abnormally large adrenals overproduce androgens
Congenital adrenal hyperplasia
() :having both male and female tissues
Gynandromorph
critical regulatory genes for sex differentiation in fruit flies
fru and dsx
- Male without (): courtship behavior weak or absent
- Female made express (): show male courtship behavior
fru
Long after sex hormones have determined the structure of the reproductive organs, they can have () on the brain
activational effects
In males, interaction with offspring may alter brain structure.
(2)
- increased density of dendritic spines
- increased number of vasopressin receptors
(): activates neurons; increases neurite outgrowth, cell viability, spine density, and synaptic plasticity
Estradiol
possible therapeutical benefit of estrogen in humans
may protect against stroke
may help with multiple sclerosis
