Sexual Differentiation and Maturation

Flashcards covering key vocabulary and concepts related to sexual differentiation, the HPG axis, and related conditions discussed in the lecture.

GnRH

Gonadotropin-releasing hormone; released by the hypothalamus approximately every two hours after puberty.

Hypothalamus-Pituitary-Gonadal Axis

The system where the hypothalamus communicates to the pituitary gland, which then communicates to the gonads.

Gonadotropins

Hormones released by the anterior pituitary gland in response to GnRH; include FSH and LH.

FSH

Follicle-stimulating hormone; in males, stimulates sperm production in the testes; in females, causes the follicle to ripen.

LH

Luteinizing hormone; in males, stimulates the production of testosterone from cells in the testes; in females, causes ovulation and the formation of a corpus luteum.

HPG Axis in Males

A simple negative feedback system that keeps testosterone levels around a set point.

Anabolic Steroids

Artificial testosterone; can inhibit the HPG axis, leading to decreased GnRH and gonadotropin production and shrinking of the testes.

Menstrual Cycle

A four-week cycle in human females involving the HPG axis, leading to changes in hormone levels and the shedding of the uterine lining.

Follicular Phase

The phase in the menstrual cycle where the follicle grows under the stimulation of FSH and produces estradiol.

Corpus Luteum

The structure formed from the remaining follicle after ovulation, which produces estradiol and progesterone.

Premenstrual Period

The period when estradiol and progesterone levels fall, leading to the shedding of the uterine lining.

Androgen Insensitivity Syndrome

A condition in which the body is not sensitive to androgens (testosterone); typically described in XY individuals who may develop female characteristics.

Five Alpha Reductase Deficiency

A condition in which an enzyme deficiency prevents the conversion of testosterone to DHT, leading to ambiguous genitalia at birth but masculinization at puberty in XY individuals.

Congenital Adrenal Hyperplasia (CAH)

A condition where an enzyme deficiency leads to low cortisol and high testosterone production in the adrenal gland, causing masculinization of external genitalia in XX individuals.

21 Hydroxylase

Enzyme in the adrenal gland that is needed to make cortisol. If not working, the precursors to cortisol are turned into testosterone.