REPRODUCTION CHAPTER 39

Sexual Development First six weeks Week 7 Birth Puberty Male and female embryos are the same Week 7 Ovaries and testes start to develop and produce hormones Ovaries-estrogen Testes-testosterone Birth Gonads produce small amounts of hormones Puberty Produce active reproductive cells

Puberty Rapid growth and sexual maturation Reproductive system becomes fully functional Usually between 9-15 Earlier in females Triggered by hormones FSH – follicle stimulating hormone LH – luteinizing hormone

Male Reproductive System FSH and LH stimulate testes to produce testosterone FSH and testosterone stimulate production of sperm Main function Produce and deliver sperm Scrotum External sac holding testes 1-3 degrees lower than body temperature Seminiferous tubules Tiny tubules within testes where sperm are produced

Male reproductive system

Sperm Development Meiosis in testes to form haploid cell Sperm is moved from seminiferous tubules into epididymis Mature and stored here Vas deferens Extends up from scrotum until it merges with urethra

Sperm Development Urethra Leads outside body through penis Glands lining MRT contain nutrients for sperm and protect from acidic FRT Seminal fluids and sperm are known as semen 50-130 million sperm in 1 ml of semen Or 2.5 million per drop

Female Reproductive Tract Ovaries – primary reproductive organ Main Function Produce ova (plural for eggs), prepare for and nourish embryo Ovaries Produce 1 egg per month (ovum)

Egg Development Follicles Surround a single egg Help egg mature for release Only about 400 eggs will be released in a lifetime Every 28 days Stimulated by the hormone FSH Meiosis – 1 egg and 3 polar bodies

Egg Release Ovulation Fallopian tubes Uterus Release of egg Fluid filled tube that carries egg using cilia to uterus Opens over ovary Fertilization occurs here Uterus Lining prepares for fertilized egg

Female Reproductive Tract Cervix Outer end of uterus Opens to vagina Vagina Canal that leads to outside of the body

Menstrual Cycle “mensis” latin meaning month Interaction of endocrine system and reproductive system Starts at puberty Ends at menopause Around age 50 Egg develops and is released Uterus prepares for fertilized egg If egg is not fertilized, uterus lining is discharged

Phases of Menstrual Cycle follicular, ovulation, luteal and menstruation Follicular Phase FSH and LH trigged by low estrogen cause follicle to develop As follicle develops, estrogen rises, uterus lining thickens 10 days

Phase 2 Ovulation Mature egg is released into one of the fallopian tubes Shortest cycle 3-4 days

Phase 3 Luteal Phase Begins after egg is released Corpus luteum forms where egg ruptured Releases estrogen and progesterone Best chance for fertilization is 2 days into luteal phase 10-14 days after completion of last menstrual cycle If implantation in uterus occurs, embryo will release hormones that keep corpus luteum functioning for several weeks

Phase 4 Menstruation No fertilization? Corpus luteum will disintegrate Less estrogen and progesterone Causes lining of uterus to shed Discharged through vagina 3-7 days After menstruation ends, low levels of estrogen trigger FSH and LH to cause follicle to mature Cycle starts over.

Sexually Transmitted Diseases Diseases spread from one person to another during sexual contact or STD’s Chlamydia 3 million cases per year Caused by bacteria Females 15-19 show highest incidence Can damage woman’s reproductive tract and cause infertility Can pass from mother to newborn via childbirth Can be asymptomatic or mild symptoms

STD’s Syphilis Gonorrhea Herpes, Hepatitis B, genital warts, AIDS Caused by bacteria Can be fatal “great imitator” Gonorrhea Spread during intercourse Herpes, Hepatitis B, genital warts, AIDS All caused by virus Cannot be treated with antibiotics Prevention Best Abstain from sexual contact Sex in a monogamous relationship Next safest Use latex condom

Fertilization and Development CHAPTER 39.4