Reproductive Physiology

·         Growth of the glandular elements of the breast is stimulated by progesterone; growth of the ductal elements is stimulated by estrogen.

·         Androgens, particularly dihydrotestosterone, are essential for regulation of the external genitalia in males. The fetus develops with multipotential internal and external genitalia. The development of male internal genitalia depends upon the presence of two hormones produced by the fetal testis—progesterone and Müllerian-inhibiting substance. The former stimulates growth and development of Wolffian ducts; the latter stimulates Müllerian duct regression.

·         Following insulin binding on muscle and adipocytes, the glucose transporter GLUT-4 is translocated to the cell membrane where it promotes glucose uptake by facilitated diffusion. GLUT-1 transporters are found virtually everywhere, as are GLUT-3 transporters. GLUT-2 transporters are found in liver, kidney, and intestinal cells. GLUT-5 transporters promote glucose absorption from the jejunum.

·         Cortisol is defined as a glucocorticoid because it promotes the conversion of amino acids to glucose (gluconeogenesis). It also decreases glucose uptake by muscle and adipocytes by decreasing the sensitivity of the cells to insulin. The net result is to provide more glucose to non-insulin-requiring cells.

·         Sperm contains chemicals that prevent sperm capacitation, thereby prolonging the viability of the sperm. In addition, the high potassium content of the secretion inhibits sperm motility, further adding to the viability. Sperm is secreted primarily by the seminiferous tubules and the alkaline nature of the secretion buffers the acidity of the vagina.

·         In nonpregnant women, the secretion of prolactin is kept tonically suppressed by secretion of dopamine from the hypothalamus. Prolactin is the main hormone of lactation. Hormone levels increase early in pregnancy due to the influence of estrogens. However, lactation does not occur early in pregnancy because estrogens and progesterone inhibit the interaction of prolactin with receptors located on the alveolar cell membranes. At term, estrogen and progesterone levels decrease and milk production begins usually within three days of delivery.

·         Glucagon secretion from pancreatic alpha cells is increased by increased plasma arginine levels

·         Q: child with deficiency of PROSTATE Gland – cause: def of 5 alpha reductase, so no DHT and no development of urogenital sinus.

·         Pituitary is NONDISCRIMINATING for testosterone, while Sertoli Cells are DISCRIMINAITNG for Testosterone i.e. it accepts testosterone from Leydig Cells only. ( remember ANABOLIC STEROID decreases Spermatogenesis)

·         HCG drives production of TESTOSTERONE in MALE FETUS, which need almost equal amount of Testosterone as an adult.

·         ESTROGEN is MITOTIC HORMONE needed to be formed from Testosterone in SERTOLI CELL for SPERMATOGENESIS.

·         LIBIDO:  

1.   testo / LH ratio

2         HTN,DM

3         Stress decreases

4         Partners

·         ERECTION: parasym

EMMISSION: symp

EJACULATION: symp & somatic motor

·         Leydig = Theca & Sertoli = Granulosa

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·         Remember, MENSTRUATION is part of FOLLICULAR phase & OVULATION is part of LUTEAL Phase.

·         Placental HCG keeps Corpus Luteum survive to produce Progesterone.

·         HPL is Growth Hormone of Placenta which also raises level of Blood Sugar and responsible for GESTATIONAL DIABETES.

·         Estrogen inhibits PIF so increases PROLACTIN Synthesis, but the same time it blocks PROLACTIN RECEPTORS, so MILK synthesis does not take place.

·         What initiates PARTURATION is decent of the head (releases PG & Oxytocin). Remember that OXYTOCIN continues PARTURATION, not INITIATE it.

·         Milk Synthesis starts just after PLACENTA is delivered as ESTROGEN level falls.

Milk Ejection starts by NIPPLE STIMULATION. Remember OXYTOCIN continues it, not initiates it.