KEY CONCEPT Human reproductive processes depend on cycles of hormones.

Eggs mature and are released according to hormonal cycles. 5. 2nd polar body ovum (egg) Follicle-stimulating hormone (FSH) and lutenizing hormone (LH) regulate egg production. meiosis produces eggs and polar bodies each egg has 23 chromosomes meiosis is completed at fertilization 46 1. Potential egg 23 2. Meiosis I 23 4. 1st polar body 23 3. Meiosis II 23

FSH, LH, and estrogen stimulate the release of eggs. follicle ruptures at ovulation egg travels into fallopian tube ruptured follicle becomes corpus luteum fallopian tube egg cell egg released corpus luteum uterine wall ovary follicle uterus 5 to 7 days to uterus

Eggs mature and are released according to hormonal cycles. The menstrual cycle has three phases. 1. flow phase: endometrium sheds (a girl’s period b/c uterine lining detaches as blood..all hormones low) 2. follicular phase: Increase in LH and FSH..ovulation occurs (egg released and can be fertilized by a sperm). Increase in estrogen causes lining to thicken 3. luteal phase: corpus luteum forms…release of progesterone and estrogen stops production of FSH and LH; increase # of blood vessels in lining

FLOW PHASE FOLLICULAR PHASE LUTEAL PHASE

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

Sperm production in the testes is controlled by hormones. Testosterone, FSH, and LH stimulate sperm production. one sex cell divides into four sperm each sperm has 23 chromosomes 1. potential sperm 4 sperm cells 2. Meiosis I 3. Meiosis II 46 23 23 23 23 23 23

Sperm cells fully mature in the epididymis. head contains acrosome midpiece contains ATP tail allows mobility 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 fraternal twins from two separate eggs Infertility makes reproduction difficult or impossible.

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, and HIV 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.