endocrine - repro Flashcards
isoform of 5a-reductase:
Expression starts at puberty
Type 1
Testosterone and DHT synthesis
Aldrostenedione to testosterone (17B-HSD) to DHT (5a-reductase)
isoform of 5a-reductase:
Found in skin - contributes to sebaceous gland activity and acne formation
Type 1
isoform of 5a-reductase:
Found in male urogenital tract, skin, hair follicles and Liver
For masculinization of ext genitalia in utero
Type 2
Leydig cell produces estrogen peripherally. Effects…
Bone maturation
Insulin sensitivity
Improves lipoprotein profile (increase HDL)
60% of androgen is bound to
sex hormone binding globulin SHBG
Androgen negative feedback effect on FSH and LH ..more on
LH
Regulation of Sertoli cell function
Stimulated by both testosterone and FSH
Expresses FSH receptor
FSH stimulates synthesis of inhibin
Loophole in male repro axis..
Intratesticular T level should be >100x more than circulating T level to maintain normal spermatogenesis
Exogenous T level increases circulating T only
True
Regulation of development of internal genitalia in male
Wolffian duct-Testosterone and presence of MIS
Regulation of development of internal genitalia in female
Mullerian duct - absence of MIS
Regulation of development of external genitalia in male
Presence of DHT
Regulation of development of external genitalia in female
Absence of DHT
GnRH neurons have been demonstrated in the feral hypothalamus by
9wks gestation
Functional connections are established between GnRH neurons and portal system by
16wks AOG
Characterized by low amplitude GnRH secretionas mirrored by LH secretion
Childhood period
Characterized by a striking increase in amplitude of LH pulses with a lesser change in frequency
Puberty
In adult male, LH is secreted in pluses approx every
2 hrs
Seminiferous tubular dysgenesis
Klinefelter syndrome
Genetic disorder in men with extra X chromosome.
Phenotypically male but with small testis and decreased germ cell
Klinefelter syndrome
Results from hereditary defect of X chromosome gene controlling androgen receptor expression
Phenotypically female but male internal genitalia
Male pseudo hermaphroditism
Androgen insensitivity syndrome
Due to decreased DHT formation
5a reductase deficiency
Normal internal genitalia but incomplete masculinized external genitalia - ambiguous genitalia. Mistaken for females at birth
5a reductase deficiency
Primary isolated gonadotropin deficiency due to inability of GnRH neurons to migrate to medico basal hypothalamus from nasal placode. With undescended testes (CRYPTORCHIDISM) and microphallus. Asso with anosmia
Kallmann syndrome
Female repro cell which expresses LH receptor
Theca cells
Female repro cell which produces androgen (primarily androstenedione)
Theca cells
Theca cells expresses what enzyme
Cyp11a1, 3b-HSD, cyp17
Female repro cell which expresses FSH receptor
Granulosa cells
Granulosa cells expresses what enzymes
17b-HSD, cyp19
Regulation of menstrual cycle when there is high freq GnRH pulses
LH production
Regulation of menstrual cycle when there is low freq GnRH pulses
FSH production
Most common cause of congenital hypogonadism
Gonadal dysgenesis or Turner syndrome
Short stature, webbed neck, low se tears, shield-shaped chest, short 4th metacarpals and sexual infantilism
Turner syndrome
Chronically a ovulation women with high androgen, estrogen, and LH levels
PCOS
Diagnosis of PCOS requires 2 out of 3 of
- Amenorrhea
- Evidence of excess androgen secretion (acne, hirsutism)
- Polycystic ovaries by ultrasound
Primary defect of PCOS
Inappropriate signals between HP axis and ovary
