23 Notes: Personal Identity – biologicalpsych.com

Gender
- Sex differences = biological
- Gender differences = thinking
Sexual differentiation
- How identify sexually
- What call self (male-female)
- Sexual differentiation begins with chromosomes
  - Female = XX chromosome
  - Males = XY
- Prenatal
  - Start with same anatomy
  - Müllerian ducts
    - Lead to female internals
  - Wolffian ducts
    - Lead to male internals
Male (XY)
- Y Chromosome
- SRY (sex-determining region)
  - Causing primitive gonads to become testes
- Testes
  - Sperm-producing organs
  - Produce androgens (male hormone)
- Wolffian ducts develop into:
  - seminal vesicles: store semen
  - vas deferens: duct from testes into penis
- Müllerian inhibiting hormone
  - Peptide hormone
  - Müllerian ducts degenerate
- Testosterone
  - Development of penis & scrotum
Females (XX)
- More estrogen than androgens
- Primitive gonads become ovaries
  - (egg-producing organs)
- Wolffian ducts degenerate
- Müllerian ducts develop
- Estrogen
Steroid Hormones
- four carbon rings
- derived from cholesterol
- 3 effects:
- 1. bind to chromosomes
  - activate or inactivate genes
- 2. bind to membrane receptors
  - like protein or peptide hormones
- 3. enter cells
  - activate proteins in cytoplasm
Androgens and Estrogens
- Not a specific chemical itself
- Androgens promote masculine features (hair)
- Estrogens promote female features (breasts)
Testosterone
- most widely known androgen
Estradiol
- most prominent type of estrogen
- higher levels in women
Progesterone
- Predominantly female
- Prepares uterus implantation
- Maintains pregnancy
Organizing effects
- mostly during critical stage
- determine develop as male or female
Activating effects
- Temporary
- Only when hormone present
- Can occur at any time in life
Sensitive period
- When event has long-lasting effect
- Testosterone impacts external genitalia in 3rd – 4th month of pregnancy
In Hypothalamus
- Sexually dimorphic nucleus
  - Part of medial preoptic hypothalamus
  - Larger in male than female
  - Linked to male sexual behavior
- Females can generate cyclic pattern of hormone release
- Males can’t
Alpha-fetoprotein
- Protein that binds with estrogen
- Present in early sensitive period
- Prevents females being masculinized by their own estrogen
Childhood Behavior
- 3-8 months old
- Show preference for toys
  - Girls look at dolls more
  - Boys look at dolls & trucks equally
- Male monkeys
  - lay with trucks and balls more
- Female monkeys play with dolls
- Prenatal injections of testosterone
  - After born, play more like boys
Activating Effects of Hormones
- Change behav. by enhancing $
- Testosterone need for male sexual arousal
- Estrogens increase sensitivity of pudendal nerve
Brain (rat studies)
- Low concentrations of dopamine
  - facilitate penile erection
  - sexually receptive postures in female
- High concentrations of dopamine
  - orgasm
- Males prefer cage where previously had sex
- “Female rats find sex reinforcing only if they get to decide when it occurs” — how know?
Humans
- High Testosterone
  - seek more sexual partners
  - even after marry or have long-term relationship
- Low Testosterone
  - Decrease sexual activity
  - Testosterone level don’t change after marriage
  - Low T more likely to marry
  - Single women high T
  - Long-term partner have low T
    - either homosexual or heterosexual
Impotence
- Men
- Inability to have erection
  - not usually caused by low T
- Treated by increasing blood circulation in penis & hypothalamus
Gender Identity
- Intersexes
  - Male & female characteristics
  - Hermaphrodites
  - Genitals-genetic sex mismatch
  - Some normal testicular tissue plus ovarian tissue
- Congenital adrenal hyperplasia
  - Overdeveloped adrenals
  - Excess release of testosterone
  - In genetic males
    - extra testosterone
    - little effect
  - In genetic females
    - Masculine physical char.
      - clitoris may resemble penis
    - Treated different by teachers…
    - Differ in childhood interests
    - More interested in rough sports
    - More aggressive as adults
    - Less interested in infants
    - Create or lengthened vagina
    - Significant sexual difficulties
    - No romantic attraction to men
    - Little or no interest in sex
    - Lack of orgasm
Testicular Feminization
- Androgen insensitivity
  - Not bind to genes in nucleus
- Genetic male
- Appearance of female
- Small penis
- Considered female until puberty
- Don’t menstruate
Gender Assignment
- In 1950s
  - Most intersexed reared as girls
  - Surgery easier to look like girl
  - Most developed male interests
  - Demanded reassignment as males
- Now
  - Recommend honesty
  - No bias toward female
  - Use predominant external appearance as gender
  - No surgery now
  - Change sexual orientation later?
- Sexual Appearance
  - Genetic males
  - Enzyme (5-reductase 2)
    - converts testosterone to dihydrotestosterone
- Inbreeding
  - genetic disorder blocks enzyme
  - penis not develop until puberty
  - identified as female as birth
- Boys usually want to switch to male gender identity
- Reassignment when teen common if:
  - born without penis
  - lost penis through accident
Multiple Mates
- Men more interested in
  - short-term sexual relationships
  - with many partners
- Evolutionarily, both work for men:
  - One-mate strategies
  - Multiple-mate strategy
- Women have less to gain
  - Limited number of pregnancies
  - But can upgrade to better mate
Mate Seeking
- Both men & women prefer
  - Healthy
  - Intelligent
  - Honest
  - Attractive
- Women prefer:
  - Good providers
    - strongest when no $ of own
  - Strong commitment
  - Body odor
    - Women prefer differ from hers
    - Immune genes dissimilar
- Men strongly prefer younger
- Differences in Jealousy
  - Men upset by sex infidelity
  - Women upset by emotional infidelity
    - Evolved or Learned
Anatomical Differences
- Longer arms, legs & hands
  - In heterosexual men
  - In homosexual women
- Brain Differences
  - Larger in gay men
    - anterior commissure
      - Pain bilateral connections
    - Suprachiasmatic nucleus (SCN)
      - Circadian rhythms
- Processing Differences
  - Landmarks for giving directions
    - Gay men
    - Heterosexual women
Sexual Orientation
- Not an arbitrary decision
- Integral part of person
- Homosexuality is a shift toward
  - In some aspects, not others
- Genetics
  - Homosexuality
    - Highest in monozygotic twins
    - Lower in dizygotic twins
    - Still lower in siblings
    - Higher incidence among maternal relatives
- Prenatal Influences
  - Lowest in oldest sons
  - Mother’s immune system can react against a protein in 1st son
  - Attacks subsequent sons more
Attraction
- Women
  - Periovulatory period
    - Mid-point of menstrual cycle
    - Sexual interest increases
    - High estrogen levels
    - Prefer men who look and act more masculine
  - Oxytocin
    - Stimulates contractions of uterus during delivery
    - Stimulates mammary gland to release milk
    - Also releases at orgasm
    - relaxation & less anxiety
    - Bonding of couples
      - Mother-child?
    - Facilitates social behaviors
    - Recognizing familiar faces
    - Recognizing blurry words (like love or kissing)
- Hormones increase activity in
  - medial preoptic area
  - anterior hypothalamus
- Men
  - Vasopressin
  - Important for parental behavior
  - Male prairie voles
  - high levels of vasopressin
  - long-term pair bonds
  - help rear their young
Pheromones
- Chemicals
- Released by an animal
- Impact members of same species
- Affect behavior (ie., sexually)
- Vomeronasal organ (VNO)
- Located near smell receptors
- Separate system
- Respond only to pheromones
- Each VNO receptor responds to just one pheromone
- No adaptation from continued exposure
- VNO is very small in humans
- No receptors have been found
- Have one type pheromone receptor located in olfactory mucosa
- Synchronize menstrual cycles
- Spend a lot of time together
- Enhance regularity of menstrual cycle
- For long-term relationships
Body Image
- Facial symmetry
  - Very difficult to find
  - Takes billons of cells in same places on each side
- Men should have:
  - broad forehead
  - relatively longer lower face
  - prominent chin and brow
  - defined cheekbones
  - chiseled jaw
- Women should have:
  - Baby face
  - Large eyes
  - Small nose
  - Narrow jaw
  - High cheekbones
  - Fatter than they think should be
- Ratios
  - Between eyes
  - 46% of total width
  - Between eyes & mouth
  - 36% of total height
  - Jessica Alba
- Overestimation
  - Men value of muscles
  - Women value of thinness
Eating Disorders
- Obesity in rats
  - “Buffet” of high-calorie foods
  - Can’t pass up options
  - Become obese
  - Lose interest in other rewards
- Fat is not happy
  - Small correlation between obesity and mood
  - Obesity not caused by depression
- Prenatal
  - high-fat diet before
  - increase appetite & body weight
- Genetics and Body Weight
  - Danish study
    - weights of adopted children
    - correlate with biological parents
  - Genetic or prenatal
  - Specific genes
  - Mutated gene for melanocortin can cause obesity
- Syndromal obesity
  - From medical condition
  - Prader-Willi syndrome
    - Genetic disorder
    - leads to obesity
    - high levels of ghrelin (peptide)
Weight Loss
- Dieting rarely effective alone
- Maintaining diet
- Implement small changes
- 20-40% success (2 years)
- Increasing exercise
- Decreasing eating
- Fructose doesn’t $ satiety path
  - Non-diet drinks high in fructose
  - Artificial sugars cause body to unlearn association between “sweet” and calories?
- Sibutramine (Meridia)
  - Appetite suppressants
- Orlistat (Xenical)
  - Block fat absorption
- Gastric bypass surgery
  - Removes part of stomach
  - Smaller meals produce satiety
Bulimia Nervosa
- Alternate dieting & overeating
- Some vomit after meals.
- Most suffer from depression
- Results in:
  - Lower levels of CCK (hormone)
  - Increased ghrelin (hormone)
  - Altered NT transmitters
    - regulate eating
- Similar to drug addiction
  - Food activates nucleus accumbens

Leave a Reply Cancel reply