Chapter 4 Flashcards
Steroidal hormones
Androgens—most common is testosterone
Estrogens—most common is estradiol
Progestins—most common is progesterone
Sexual dimorphism (Two sexes)
Beginning at conception
-The genetic stage
-Inheritance of sex chromosomes -(X’s and Y’s)
The gonadal stage
-Development of reproductive organs
The hormonal stage (androgens and estrogens)
-Prenatally (development) and pubertal (maturation)
Internal and external genitalia
Flood of androgens producing male, none produces female.
Internal reproductive system—about 6 weeks after conception
External genitalia—about 3 months into prenatal development
Allows for the possibility of errors in developing either the male or female patterns
Wolffian system
The capacity to develop according to the male pattern if exposed to androgens
Müllerian system
The capacity to develop according to the female pattern if not exposed to androgens
Male Reproductive Organs
Presence of androgens
Prompts development of Wolffian system
Secretion of Müllerian- Inhibiting Substance (causes the Müllerian system to degenerate)
Gonads develop into testes
Female Reproductive Organs
Absence of androgens
Allows the Müllerian system to develop
The Wolffian system degenerates
Gonads develop into ovaries
Developing External Repro Organs
Begins during the third month of prenatal development
Again, androgens are critical
Presence of androgens creates the male pattern
No androgens = female pattern
Gender differences in NS
Brains largely intersex
Many brain structures contain receptors that are sensitive to androgens and estrogen creating the possibility for influence not just during the prenatal period but later in life, especially puberty
Sex differences are not “hardwired” by exposure to prenatal hormones, exposure to hormones later in life may be more influential
Sexually dimorphic nucleus (SDN)
In the hypothalamus
The most prominent brain difference
2.5 times larger in men than in women
Function in humans is not understood
May be related to sexual behavior/gender identity
Luteinizing hormone
Causes follicle to rupture and release ovum
Maturation of sperm
follicle stimulating hormone
Stimulates follicles to mature an ovum
Involved in sperm production
LH & FSH
Released by Pituitary
Stimulate gonads to increase production of estrogens and androgens
Results in maturation of the genitals
Produces menstrual cycle
X0 = Turner Syndrome
Missing chromosome
Appear female at birth
But Müllerian system has degenerated
No functioning ovaries (no estrogen, no puberty)
Hormone supplements
XXY = Klinefelter Syndrome
Male internal and external genitalia
Small testes, usually sterile
May develop breasts and a feminized body during puberty
Developmental disabilities
Congenital adrenal hyperplasia
Caused by an increase in androgen production
For XY males, typically few problems occur (early puberty)
For XX females, causes masculinization of external genitalia
Surgery (controversial)
Androgen insensitivity syndrome
Affects chromosomal (XY) males Androgen receptors do not work
No production of Müllerian-inhibiting substance
External genitalia appear female, but have undescended testes
No internal female genitalia
Not typically identified until puberty
Fail to reach menarche and do not grow pubic hair
Identify as female
Intersexuality (Disorders of Sexual Development)
Traditional diagnostic term: hermaphroditism
Restricted to individuals who have both ovarian and testicular tissue
5-alpha-reductase deficiency
Extremely rare
Affects XY males
Appear female at birth, but ambiguous
Develop according to male pattern during puberty (respond to androgens)
About 60% developed male gender while 40% retained female gender
Premenstrual Syndrome (PMS)
Tension or irritability, depression, disruption in life activities, headache, abdominal bloating or discomfort, breast tenderness etc…
Result of hormonal changes prior to menstruation
Difference b/w physical menstrual symptoms and emotional and cognitive symptoms
PMS Research
No relationship b/w hormone levels and experience of PMS
No difference b/w sexes
Some women reported elevated mood before and after
Cyclical mood variations, but not typical of PMS
Women and men may attribute negative moods to PMS
Instead, PMDD (premenstrual dysmorphic disorder)
Testosterone & Aggression
High testosterone related to being impulsive (e.g. drugs & alcohol) and antisocial (lack of consideration for others), but not strongly w/ aggression
Aggression increases testosterone
Aggression and testosterone are mediated, either biological, or social
Cultural Differences in Descriptions
Native American cultures
berdaches, or “two spirit” people (not intersex, not homosexual)
India
hijras, or a “third sex” (may be intersex)
