Reproduction and Development Chapter 26, part C Reproduction and Development

Procreation: Delivering the Sperm to the Egg Prevention: abstinence, barriers, surgical, & pills Phases of Coitus (sexual intercourse or copulation) Excitement Plateau Orgasm Resolution Erection Reflex CNS & spinal integration

Procreation: Delivering the Sperm to the Egg Figure 26-15: The erection reflex

Fertilization: Union of Male & Female Chromosomes Sperm capacitation Swimming & attractants Egg contact Penetration Nuclear fusion (Zygote) Figure 26-16b: Fertilization

Fertilization: Union of Male & Female Chromosomes Figure 26-17: Fusion of sperm and egg to form a zygote

Zygote Development: Cell Division & Implantation Cell divisions Blastocyst Migration to Uterus Implantation

Zygote Development: Cell Division & Implantation Figure 26-18: Ovulation, fertilization, and implantation of an ovum

Placenta and Further Embroynic Development Amnion Chorion Placenta Exchange Hormones Human chorionic Gonadotropin-hCG Progesterone

Placenta and Further Embroynic Development Figure 26- 19a, b: The placenta

Birth: Parturition Labor Rhythmic Uterine Contractions Cervical dilation Delivery Baby Placenta

Figure 26-20: Parturition: the birth process Birth: Parturition Figure 26-20: Parturition: the birth process

Regulators of Parturition Labor onset Stretch stimulus Oxytocin Prostaglandins Positive feedback  Stretch   Oxytocin Birth ends Stimulus Figure 26-21: The positive feedback loop of parturition

Lactation: Producing and Releasing Milk Estrogen & progesterone Preps mammary tissues Prolactin inhibiting H: Prolactin  milk production (other roles in fertility) Sucking stimulus  Oxytocin  "Milk let-down" reflex

Lactation: Producing and Releasing Milk Figure 26-23: The hormonal control of milk secretion and release

Reproductive Maturation: Puberty Increase production of sex hormones Maturation of reproductive organs & gamete production 20 sexual characteristics Males: pubic hair, beard, deep voice, "wedge" body form &  muscle mass Females: menarche, pubic hair, breasts & "pear shape" body form

Later in Life Menopause: Female "Change-of Life" Ovaries  responding to GnRH  Levels of estrogen & progesterone produced Cease egg development "Hot flashes" ,  osteoporosis risk (hormone replacement debate) "Andropause" (?): Male changes are gradual  Sex hormones:  muscle mass,  libido,  erections Viagra: PNS  NO  cGMP   degradation

Summary Genes and hormones direct bipotential reproductive tissues to differentiate into males or females Spermatogenesis is regulated by FSH & LH, testosterone and inhibin influence on spermatocytes, Sertoli & Leydig cells Menstrual cycle coordinates egg maturation with endometrium, and is regulated by GnRH, LH & FSH  estrogen, progesterone & inhibin (and placental hCG)

Summary Fertilization, implantation, placental nutrition, lead to parturition (driven by oxytocin in a positive feedback reflex) Puberty initiates reproductive maturity, menopause the end of it