PSI- Reproductive Systems of Males and Females Chapter 13 Lesson 1 Learning Objective : You will learn how the reproductive organs of the human female and male generate eggs and sperm and how sexual activity may lead to fertilization and pregnancy

Male Reproductive System Adult males have many body characteristics that differ from adult females. Males usually have  more body hair  deeper voices  larger, more muscular bodies This starts with puberty and occurs as boys get older and their reproductive systems grow toward maturity

Male Reproductive Organs- Testes (testicles) Males have two testes that produce sperm Males do not begin to produce sperm until their reproductive system matures (puberty) Testes are inside a baglike structure called the scrotum The scrotum hangs outside of the body cavity Keeps testes slightly cooler than rest of body for sperm production Bladder Prostrate gland Vas deferens Scrotum Penis Testis Epididymis Urethra Seminal vesicles

Organs of Sperm Production The testes contain tightly coiled tubes called seminiferous tubules Sperm travels from seminiferous tubules to a storage organ within the scrotum called the epididymis The epididymis connects to muscular ducts or tubes called the vas deferens Seminal vesicle Prostate gland Scrotum Testis Penis Urethra Epididymis Vas deferens Bladder

Organs of Sperm Transfer cont’d Male organ that transfers sperm to a female’s reproductive tract is a penis During sexual activity, sperm move from vas deferens into a short ejaculation duct that connects to a tube called the urethra The urethra carries sperm out of the body and also carries urine, but ejaculation and urination never occur at same time When a male is sexually excited, the tissues of the penis fill with blood. Extra blood causes an erection, or firming of the penis An erection is needed for the penis to enter a female’s reproductive system During ejaculation, sperm leave the epididymus, enter the vas deferens, move to the urethra, travel down the urethra, and out the end of the penis. Sperm can leave the penis without the male’s knowledge, either before ejaculation or during sexual activity that does not result in ejaculation

Sperm & Semen Each sperm consists of a head, a midpiece, and tail The head contains a nucleus, and the midpiece contains mitochondria that release energy The tail whips back and forth to propel the sperm forward Males ejaculate about 2-5 mL of semen on average Semen ejaculated out of the body contains between million sperm The seminal vesicles are a pair of glands that make most of the liquid in semen Seminal vesicles produce a thick, yellowish, liquid that contains mucus, vitamin C, hormone-like substances, and an enzyme that helps thicken the semen Sperm Production Males start producing sperm during puberty (about 85 mil sperm per day) Usually occurs between years old Males can continue to make healthy sperm for the duration of life Sperm live for about 48 hours inside the body

Female Reproductive System Female reproductive system produces eggs Whereas males begin to produce sperm at puberty, females begin producing eggs before she is born Unlike a male, all reproductive organs of female are inside her body

Female Reproductive Organs Two folds of skin, called labia, protect the opening to a female’s reproductive system Beyond the opening, inside is a thin-walled chamber called the vagina This is where semen is deposited Above the vagina, further inside the body, is the uterus The uterus is a thick, muscular organ where a fertilized egg develops Tissue called endometrium lines the uterus The neck or opening of the uterus into the vagina is called the cervix During childbirth, the cervix gets wider, or dilates, so that the baby can come out of the mother’s body *Hymen Fallopian tube Ovary Uterus Cervix Vagina Labia

Ovaries and Fallopian Tubes A pair of organs called ovaries produce eggs An egg released from an ovary moves into a fallopian tube, which connects the ovary to the uterus Fertilization usually occurs while the egg is in the fallopian tube The fallopian tubes contain cilia, which are hairlike structures that move the egg toward the uterus Fallopian tubes Ovary Uterus Cervix Vagina

Females and Puberty Females usually begin puberty between the ages of Remember, that females produce eggs before they are born When puberty starts, the female’s body signals to begin releasing eggs from ovaries Typically, a female usually releases one egg cell every 4 weeks on average Cells of the ovary surround, protect, and nourish each egg cell and its surrounding cells A follicle is an egg cell and its surrounding cells A female at birth has about 400,000 follicles/eggs The release of an egg from a follicle into a fallopian tube is called ovulation

Menstrual Cycle & Menstrual Flow Before a follicle releases an egg, other changes happen in a female’s body The changes that take place before, during, and after ovulation are called the menstrual cycle Menstrual cycles usually last about 28 days During the menstrual cycle, the endometrium thickens and the number of blood vessels in it increases to support a fertilized egg If the egg not fertilized, the endometrium breaks down and sloughs off Days Endometruim Ovulation Thickness of endometrium increases Menstrual flow This tissue (some blood and some tissue) leave the vagina as menstrual flow (also called a period) and usually lasts 4-7 days After menstrual flow stops, the endometrium thickens again

Ovulation About 2 weeks after first day of period, ovulation occurs Usually, only one egg released If egg fertilized, a zygote forms When embryo enters uterus, it implants in endometrium If this happens, menstrual bleeding does not occur One of the first signs of pregnancy Between ages of 40-54, most women stop ovulating and no longer have menstrual cycle Called menopause As women get older, it becomes more difficult to get pregnant Menopause