Both male and female reproductive functions controlled by hormones Both male and female reproductive functions controlled by hormones. We’ve already discussed some of those. Let’s review a bit and Discuss some additional hormones important in reproduction.

It all starts with the pituitary gland

Pituitary gland secretes follicle stimulating hormone (FSH): FSH stimulates follicles to develop in ovary; Follicles then produce estrogen. FSH (along with testosterone) stimulates seminiferous tubules of testes to produce sperm Estrogen: Stimulates development of female sexual characteristics Stimulates contractions of oviduct Stimulates endometrium of uterus to proliferate Inhibits secretion of more FSH from pituitary (Seminiferous tubules don’t secrete any other hormones, so FSH secretion by pituitary remains constant)

Pituitary gland secretes luteinizing hormone (LH): LH stimulates ovulation, then stimulates follicle to develop into corpus luteum; this then secretes progesterone LH stimulates interstitial cells of testes to secrete testosterone Progesterone Continues to inhibit secretion of FSH from pituitary Keeps endometrium of uterus ready for embryo implantation Inhibits contraction of muscle (myometrium) of uterus Testosterone Stimulates development of male sexual characteristics Does not inhibit LH secretion by pituitary, so LH remains constant

If fertilization occurs: If fertilization does not occur: The embryo begins to develop its placenta, which secretes human chorionic gonadotropin (HCG). Corpus luteum stops secreting progesterone and degenerates. HCG stimulates corpus luteum of ovary to continue secreting progesterone; this inhibits menstruation and inhibits the pituitary from secreting FSH, so another follicle will not start to develop As levels of progesterone fall, menstruation occurs as the myometrium (muscle) of the uterus contracts and the functional layer of its endometrium falls off. The pituitary is no longer inhibited and begins to secrete FSH again

The pituitary gland secretes two more hormones involved in reproduction: During pregnancy, pituitary secretes prolactin; this causes the breast to develop milk-secreting glands and begin the production of milk

The pituitary also secretes oxytocin which has a number of both physiological and psychological effects. During both menstruation and childbirth, the pituitary secretes oxytocin, which causes myometrium (muscle) of the uterus to contract. If labor and childbirth do not normally develop and/or progress quickly enough, additional oxytocin may be used to “induce” or speed up labor

During breastfeeding, sucking on the nipple causes pituitary to secrete oxytocin which causes smooth muscle in the breast to contract and express the milk.

Increased levels of oxytocin also leads to feelings of both emotional and sexual attraction: “The hormone of love”. Oxytocin levels increase sharply during early stages of attraction and sexual arousal. This starts a “positive feedback loop” which increases your receptivity even more and increases your sensitivity to sexual signals from others and to sexual stimulation. Oxytocin continues to rise during sexual activity, eventually triggering both the muscular contractions and the positive emotional responses of orgasm.

Oxytocin: significant differences between men and women Women secrete more oxytocin in response to emotional and verbal cues; Men secrete more oxytocin in response to physical and visual cues. Women produce more oxytocin than men during arousal and intercourse, but also require these higher levels to get the same level of arousal and to reach orgasm.

Oxytocin: significant differences between men and women Oxytocin levels: Fall rapidly in men after intercourse, but Stay elevated much longer in women. This has been linked to women’s increased desire for a continued connection with her mate after intercourse, and to men’s relative lack of this desire.

Supplemental oxytocin can be used to increase this Decreased levels of oxytocin result in decreased levels of sexual response in both men and women and Supplemental oxytocin can be used to increase this x