KEY CONCEPT Female and male reproductive organs fully develop during puberty.

The female reproductive system produces ova. There are two main functions of the female reproductive system. produce ova, or egg cells provide a place where a zygote develops uterus cervix rectum vagina urethra urinary bladder pubic bone ovary fallopian tube

Estrogen has three main functions. develop female sexual characteristics develop eggs prepare uterus for pregnancy

The male reproductive system produces sperm. There are two main functions of the male reproductive system. produce sperm cells deliver sperm to the female reproductive system urinary bladder vas deferens pubic bone prostate gland penis urethra testis scrotum epididymis bulbourethral gland rectum seminal vesicle

Testosterone has two main functions. developing male sexual characteristics producing sperm

KEY CONCEPT 34.2 Human reproductive processes depend on cycles of hormones.

Eggs mature and are released according to hormonal cycles. potential egg first polar body second polar ovum (egg) Meiosis I Completed Meiosis II only after sperm enters 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

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. flow phase: endometrium sheds follicular phase: ovulation occurs luteal phase: corpus luteum forms

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 potential sperm 4 sperm cells Meiosis I Meiosis II

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.

KEY CONCEPT 34.3 Development progresses in stages from zygote to fetus.

The zygote becomes a blastocyst and implants in the uterus. The fertilized egg implants into the uterus and is nourished by the placenta and umbilical cord. The zygote becomes a blastocyst and implants in the uterus. ectoderm develops into skin and nervous system mesoderm develops into Internal tissues and organs endoderm develops into digestive organs and their lining blastocyst uterine wall Implantation of blastocyst

The blastocyst becomes an embryo. Embryonic membranes protect and nourish the embryo. amniotic sac cushions embryo. placenta connects mother and embryo. umbilical cord connects embryo to placenta. placenta umbilical cord uterus amniotic sac

A zygote develops into a fully formed fetus in about 38 weeks. Human pregnancies are divided into trimesters. 1st trimester: body plan and early development

2nd trimester: fetus more active, developed

3rd trimester: all organs fully formed After about 38 weeks, fetus is ready to be born.

The mother affects the fetus, and pregnancy affects the mother. The fetus depends on the mother for all its nutrition. mother's diet must support fetal health mother must avoid toxic chemicals

The mother’s health is affected by pregnancy in a number of ways. increase in Calories and body weight pregnancy hormones affecting homeostasis regular medical checkups needed

KEY CONCEPT 34.4 Physical development continues through adolescence and declines with age.

Birth occurs in three stages. Stage one of birth is the dilation of the cervix. contractions push cervix open if cervix dilates too little, C-section done STAGE 1 As regular, strong contractions occur, the cervix dilates and the baby turns.

Stage two is the emergence of the baby. baby usually born headfirst oxytocin stimulates milk production STAGE 2 The baby is pushed through the cervix and out of the vaginal canal.

Stage three is the expulsion of the placenta. placenta detaches from uterine wall contractions helps control bleeding STAGE 3 Contractions continue, expelling the placenta and helping to control bleeding.

Human growth and aging also occur in stages. Genetics, hormones, lifestyle, environment affect all stages. during infancy, growth is rapid during childhood, motor and language skills develop

Genetics, hormones, lifestyle, environment affect all stages. during puberty, sexually maturity begins during adolescence, growth is rapid and the brain rewired adulthood marks the peak of skills and independence

Aging is also affected by genetics, hormones, lifestyle, environment. Effects of aging can be reduced with good diet, exercise, and continued learning. Jerry Peel at age 1 1/2 Jerry Peel at age 17 Jerry Peel at age 71