THE SEX CELLS • THE EGG= FEMALE SEX CELL • SPERM = MALE SEX CELL • FERTILIZATION= JOINING OF EGG AND SPERM • A ZYGOTE=A FERTILIZED EGG • SEX CELLS= HALF THE NUMBER OF CHROMOSOMES AS OTHER CELLS • CHROMOSOMES CONTAIN GENES THAT GIVE US OUR TRAITS • A TRAIT IS A CHARACTERISTIC YOU HAVE.

Male Reproductive System • The male reproductive system is specialized to produce sperm and the hormone testosterone. The structures of the male reproductive system include the testes, scrotum, and penis.

THE MALE REPRODUCTIVE SYSTEM • TESTOSTERONE = A HORMONE THAT CONTROLS MALE CHARACTERISTICS SUCH AS • VOICE, • FACIAL HAIR, • BROAD SHOULDERS AND • SPERM PRODUCTION. • SPERM = A TINY PACKAGE OF CHROMOSOMES THAT CAN SWIM. • SPERM CONSISTS OF A HEAD AND A TAIL.

THE PATH OF SPERM • SPERM CELLS ARE PRODUCED IN THE TESTES. • THEY TRAVEL OUT OF THE TESTES AND MIX WITH SEMEN • SEMEN CAN CONTAIN 5-10 MILLION SPERM IN ONE DROP. • SEMEN LEAVES THE BODY THROUGH THE URETHRA • MUSCLES NEAR THE BLADDER CONTRACT TO PREVENT URINE AND SEMEN FROM MIXING.

Female Reproductive System • OVARIES ARE ENDOCRINE GLANDS THAT PRODUCE ESTROGEN AND THE FEMALES EGGS. • ESTROGEN CREATES FEMALE CHARACTERISTICS SUCH AS BREASTS AND WIDE HIPS.

THE PATH OF THE EGG CELL • EACH MONTH AN OVARY RELEASES A MATURE EGG. • THE EGG ENTERS THE FALLOPIAN TUBE (OVIDUCT) • THE EGG MOVES TO THE UTERUS • IF FERTILIZATION OCCURS, THE EGG IMPLANTS ITSELF IN THE UTERUS WALL. • IF NO FERTILIZATION OCCURS, THE EGG PASSES THROUGH THE CERVIX INTO THE VAGINA AND THEN OUT OF THE BODY.

THE MENSTRUAL CYCLE • BEGINS AS AN EGG STARTS TO DEVELOP IN THE OVARY • THE UTERUS PREPARES FOR THE EGG BY PRODUCING A LINING OF BLOOD. • 2 WEEKS INTO THE CYCLE THE EGG IS RELEASED FROM THE OVARY AND BEGINS ITS 1-2 DAY JOURNEY THROUGH THE OVIDUCT. • IF FERTILIZATION DOESN’T OCCUR, THE EGG PASSES THROUGH THE BODY FOLLOWED BY THE UTERINE LINING. • MENSTRUATION LASTS ABOUT 3-5 DAYS, DURING WHICH TIME A NEW EGG IS DEVELOPING IN THE OVARY.

THE MENSTRUAL CYCLE

Changing Hormone Levels • A woman’s hormone levels change throughout the menstrual cycle. The graph shows the levels of one female hormone, known as LH, during the menstrual cycle.

Level of LH Reading Graphs: What does the y-axis show? Changing Hormone Levels

12,12,12 Interpreting Data: What is the level of LH on day 1? On day 17? On day 21? Changing Hormone Levels

The Menstrual Cycle • During the menstrual cycle, an egg develops in an ovary. At the same time, the uterus prepares for the arrival of an embryo.

Section 3: Pregnancy, Development, and Birth • What are the changes that occur to the zygote, embryo, and fetus during development? • How is the developing embryo protected and nourished? • What happens during childbirth? • What changes occur as a person develops from infancy to adulthood?

PREGNANCY, BIRTH, CHILDHOOD • THE PLACENTA DEVELOPS BECOMING THE LINK BETWEEN THE MOTHER AND THE BABY • THE ROPE LIKE UMBILICAL CORD DEVELOPS BETWEEN THE MOTHER AND THE EMBRYO. • FROM THE 9TH WEEK THE EMBRYO IS CALLED A FETUS. • THE FINAL 3 MONTHS PREPARE THE FETUS TO SURVIVE OUTSIDE THE MOTHERS BODY. • THE BIRTH AT 9 MONTHS TAKES PLACE IN THREE STAGES.

Development Before Birth • THE ZYGOTE DIVIDES UNTIL IT BECOMES A HOLLOW BALL THAT ATTACHES TO THE LINING OF THE UTERUS. FOR THE NEXT 8 WEEKS OR SO, THE DEVELOPING HUMAN IS CALLED AN EMBRYO. Zygote

Development Before Birth Zygote Eight-Cell Stage Hollow Ball

Development Before Birth • THE HOLLOW BALL OF CELLS GROWS INWARD AND DEVELOPS INTO A FLUID FILLED SAC CALLED THE AMNIOTIC SAC. Zygote Eight-Cell Stage Hollow Ball

Development Before Birth • . Zygote Eight-Cell Stage Hollow Ball Stage When Folding Begins

Development Before Birth • The zygote develops into an embryo and then into a fetus. Differentiation leads to specialized cells, tissues, and organs. Zygote Eight-Cell Stage Hollow Ball Stage When Folding Begins Embryo With Three Layers

PREGNANCY • THE PLACENTA DEVELOPS BECOMING THE LINK BETWEEN THE MOTHER AND THE BABY • THE ROPE LIKE UMBILICAL CORD DEVELOPS BETWEEN THE MOTHER AND THE EMBRYO. • FROM THE 9TH WEEK THE EMBRYO IS CALLED A FETUS.

BIRTH • FIRST STAGE • LABOR PAINS SIGNAL THE BEGINNING OF LABOR. • THE CERVIX ENLARGES • THE UTERUS CONTRACTS • 2ND STAGE IS CALLED DELIVERY. • THE BABY IS PUSHED COMPLETELY OUT OF THE UTERUS • 3RD STAGE OF BIRTH IS THE AFTER BIRTH WHEN THE PLACENTA AND OTHER MEMBRANES ARE PUSHED OUT

Protection and Nourishment • The membranes and other structures that form during development protect and nourish the developing embryo, and later the fetus.

Birth • There are two types of twins: identical twins and fraternal twins.

PHYSICAL CHANGES OF ADOLESCENCE • PUBERTY- THE AGES OF 9-14 YEARS, • A PERSON GROWS TALLER, • VOICES CHANGE, • SEX ORGANS DEVELOP, • SKIN PRODUCES MORE OILS, • BREASTS DEVELOP, • SPERM PRODUCTION BEGINS, • HAIR DEVELOPS ON THE BODY

MENTAL CHANGES. • 13-15 A TEENAGER BEGINS TO THINK AND REASON LIKE AN ADULT. • TEENS BECOME MORE SOCIAL • THEIR FRIENDS TAKE ON A GREAT IMPORTANCE. • TEENS ARE UNDER THE INFLUENCE OF PEER PRESSURE.

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