KEY CONCEPT Human reproductive processes depend on cycles of hormones.

Eggs mature and are released according to hormonal cycles. Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) regulate egg production. meiosis produces 1 egg and 3 polar bodies each egg has 23 chromosomes Meiosis is started while in the womb (Prophase I,) put on hold 2 million cells ready to enter Meiosis after puberty starts Every 28 days a cell (oocyte) is released. Meiosis II complete with fertilization. potential egg first polar body second polar ovum (egg) Meiosis I Completed Meiosis II only after sperm enters

FSH, LH, and estrogen stimulate the release of eggs. follicle ruptures at ovulation egg travels into fallopian tube (fertilized) 5-7 days Release 400 to 500 eggs in a lifetime ruptured follicle becomes corpus luteum (yellow body) fallopian tube egg cell egg released corpus luteum uterine wall ovary follicle uterus 5 to 7 days to uterus

The menstrual cycle has three phases. Every 28 days flow phase: endometrium sheds Day 1 to 5 blood, mucus, tissue fluid contractions = cramps 2. follicular phase: ovulation occurs Day 6 to 14

High levels of estrogen cause the endometrium to thicken. High levels of LH, cause the follicle to rupture – releases the egg. Ovulation – about day 14 3. luteal phase: corpus luteum turns yellow Day 15 to 28 Corpus luteum breaks down and stops secreting hormones. Causes you to shed lining and flow begins.

The menstrual cycle stops at menopause. cycle continues until a woman’s mid-40’s or 50’s decline in hormone levels make cycles irregular eventually, cycle stops altogether, early onset menopause in 30’s can be caused by hysterectomy, ovarian cancer, hormonal issues

Testosterone, FSH, and LH stimulate sperm production. Sperm production in the testes is controlled by hormones. Starts during puberty. Testosterone, FSH, and LH stimulate sperm production. one sex cell divides into four sperm each sperm has 23 chromosomes Males produce millions of sperm a day (approx. 85 million per testicle) Ejaculate about 300 million. potential sperm 4 sperm cells Meiosis I Meiosis II

Sperm cells fully mature in the epididymis. head contains acrosome and nucleus (secretes enzymes to allow penetration of egg) midpiece contains mitochondria which makes ATP tail (flagellum) allows mobility Sperm production declines with age. defective acrosome head midpiece tail mitochondria nucleus with 23 chromosomes

Fertilization occurs when a sperm cell joins an egg cell. Sperm penetrates an egg. membrane keeps out other sperm nucleus of sperm joins with egg zygote formed

Multiple zygotes can result from fertilization. identical twins from the same egg/sperm Also called “monozygotic” fraternal twins from two separate eggs Also called “Dizygotic”

Infertility makes reproduction difficult or impossible. Sperm count is sometimes low due to toxins in the environment. 10% of U.S. couples or 6.1 million

IVF – Invitro Fertilization Cost can be $12,000 and up per treatment. 1978 Louise Brown in England “1st test tube baby”

Sexually transmitted diseases affect fertility and overall health. Sexually transmitted diseases (STDs) are passed from one person to another during sexual contact. bacterial STDs include chlamydia, syphilis, gonorrhea viral STDs include hepatitis B, genital herpes, human papillomavirus (HPV) (cervical cancer – vaccine now available), and HIV

Viral STDs can be treated, but there is NO CURE for these diseases. Bacterial STDs can be treated, and in many cases, cured with antibiotics A parasite causes trichomoniasis, which can affect fertility. Viral STDs can be treated, but there is NO CURE for these diseases. STDs attack reproductive organs. can cause infertility untreated, some can be fatal STDs can be avoided by abstinence or by using a condom.