Physiological Psychology: Chapter 11 Flashcards
Sex Hormones
• Released mostly by gonads and to a lesser degree be adrenal glands affect the brain, genitalia, and other organs.
Two Types of Sex Hormones
- Androgens (e.g. Testosterone)
- Estrogens (e.g. Estradiol)
- Both sexes have each.
Organizing Effects
- Occur mostly at sensitive stages of prenatal development
* Determine whether the brain and body will develop male or female characteristics
Activating Effects
• Occur at any time of life and temporarily activate a particular response
Organizing Effects of Sex Hormones
- Sexual differentiation begins with 23rd pair of chromosomes.
- Female mammal has two X chromosomes, a male has an X and a Y.
Organizing Effects and Prenatal Development
- Up to 7 weeks, XX and XY fetuses are identical
* Both have primitive gonads, Müllerian ducts and Wolffian ducts
Wolffian Ducts
• Precursors to other male internal reproductive organs: vas deferens, seminal vesicles
Müllerian Ducts
• Precursors to other female organs: oviducts, uterus, upper vagina
SRY Gene
• On the Y chromosome
• Causes primitive gonads to develop into testes and other internal male structures (e.g. testes)
• Testes produce androgens
• Androgens induce the development of external male sex organs
penis and scrotum
No SRY Gene
- On the XX chromosome
- Primitive gonads develop into ovaries and other internal female structures
- Lack of androgen induces development of external female sex organs
Estrogens
- Necessary for complete feminization as adult
- XX ovaries do not release estrogens
- Sex organs will be normal
- Brain areas will be affected
- Sexual behavior will be affected
Brain Differentiation
- Sex hormones affect apoptosis (the way the brain strengthens some connections and gets rid of others)
- Results in differences in size of brain structures in males and females
Sexually Dimorphic Nucleus (SDN)
- In hypothalamus
* Larger in males, smaller in females
Brain Organization
• Hypothalamus in females generates cyclical pattern of hormone release.
Drug Effects during Prenatal Development
- Does not affect XX as much as it affects XY
- Alcohol, marijuana, cocaine, some antipsychotics block androgen effects (feminize)
- Substance used to line plastic bottles increase estrogens (feminize).
Turner’s Syndrome
- X0; there is no second chromosome
- Needs Y for testes, X for ovaries
- Will appear female and have normal female sex organs, but they will not work properly internally
- Will not go into puberty
Androgen Insensitivity Syndrome
- Affects XY
- Testes develop and produce androgen but fetus is not responsive to it
- Male internal and external sex organs do not develop
- Appear female
- Often caught at puberty
- Don’t have ovaries
- Do have testes (un-descended)
Congenital Adrenal Hyperplasia (CAH)
Excess androgens released by adrenal glands
Does not have an effect on XY
• Masculinizes XX
• Enlarged clitoris, fused labia
• In extreme cases, structures look like deformed penis and scrotum
• May be surgically altered to feminize
• There is sort of a continuum based on how much androgen is being secreted
• No testes, but there are ovaries
CAH XX
- Usually reared as females
- Show “tomboy” behaviors
- Girls draw more animate objects like people and dogs, boys tend to draw more inanimate objects such as trucks
- Higher incidence of homosexuality and bisexuality
- Alters brain development; hypothalamus develops in a more masculine way
- Debate about rearing male
Klinefelters Syndrome
- XXY
- Will have testes because of the Y chromosome
- Males, but feminized
- Smaller penis and testicles
- Behaviorally shyer than most boys
- May develop breasts at puberty
XYY
- Very masculine males
- More muscle mass
- Masculine features more prominent
- Higher levels of testosterone
- Assumed that more XYY males are incarcerated because of high levels of testosterone and its association with violence, though it was proven to not be true
Activating Effects of Sex Hormones
- Temporary effects that the hormones are going to have
* Sex hormones necessary for puberty
Activating Effects of Sex Hormones in Males
- Testosterone
* Oxytocin
Testosterone
- Highest levels from 15-25, but declines with age
- Aggression
- Sexual interest; not associated with impotence. 2 way relationship.
- Has the same effects on females
- Spatial skills; decrease as men age
- Klinefelters males have poor spatial skills because they are feminized
