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