The Human Reproductive System

Male Reproductive System urinary bladder seminal vesicles prostate gland urethra penis rectum epididymis Cowper’s gland testis/testes vas deferens scrotum

Male Reproductive System (frontal view) See p. 62 in Review book

Male Reproductive System Scrotum – sac of skin that holds testes. Hangs below body to keep testes cool. Sperm cannot be produced if body is too warm. Testes move into scrotum just before birth. Testis/testes – male gonads. Made up of small, coiled tubes – seminiferous tubules. 300-600 per testis. Immature sperm made here. Secrete testosterone

Male Reproductive System Epididymis – storage area in upper rear of testis. Immature sperm move here to mature – takes 18 hours. Vas deferens – tube that leads upwards from each testis into lower part of abdomen from epididymis. Cowper’s gland – produces fluids that nourish sperm and protect them from the acidity of female. Combination of sperm and fluids - semen

Male Reproductive System 6. Rectum – holds wastes 7. Seminal vesicles – same job as Cowper’s gland 8. Urinary bladder – stores urine 9. Prostate gland – same job as Cowper’s gland and seminal vesicles 10. Urethra – passageway for excretion of urine and for sperm to leave body. Vas deferens empties into urethra

Male Reproductive System 11. Penis – male reproductive organ. Facilitates internal fertilization Ejaculation – muscular contractions force semen through urethra. Before, during and after ejaculation reflex actions keep outlet of bladder closed

Hormones and Negative Feedback in Males Negative Feedback – change that leads to a response that causes something to counteract that change Luteinizing Hormone (LH) – stimulates testes to produce testosterone Testosterone – stimulates development of sperm. Once there is a large number of sperm, puberty is complete.

Hormone Negative Feedback System

What is the effect of high levels of LH? Testosterone is produced What is the effect of high levels of testosterone? Slows production of LH which in turn slows production of testosterone What is the overall outcome of this on-off negative feedback system involving LH and testosterone? Nearly constant level of both hormones - homeostasis

Another Way of Looking at Negative Feedback in the Male Reproductive System Brain Pituitary gland Male Reproductive Organs target cells – receptor cells LH stimulates the testes cells

Male Reproductive System and Hormones Explain how LH stimulates the testes to produce testosterone. Circulates in the blood- reaches the testes target cells – stimulates them to produce testosterone What happens when the levels of testosterone are too high in the body? LH level drops What is negative feedback and how does it maintain homeostasis? Change in conditions triggers response in body to counteract that condition. Keeps hormones in balance

Female Reproductive System oviduct ovary Urinary bladder uterus urethra rectum cervix vagina

Female Reproductive System (frontal view) See p. 61 in Review book

Female Reproductive System Ovary – female gonads. Secrete estrogen – produces secondary characteristics, menstrual cycle Produces eggs – 2 ovaries 4cms long, 2 cms wide

Follicles – each ovary contains 200,000 egg sacs called follicles Follicles – each ovary contains 200,000 egg sacs called follicles. In each follicle is an immature egg. All the eggs are present at birth. During the woman’s lifetime 500 eggs mature When an egg matures, follicle moves to surface of ovary. Follicle breaks & releases the egg – ovulation Egg can be fertilized for about 24 hours after ovulation

Female Reproductive System 2. Oviduct (fallopian tube) – Each ovary is near but not connected to oviduct. Tube with funnel-like opening. Cilia line it to create a current that draws the egg into the tube. Egg is fertilized in the oviduct 3. Uterus – thick, muscular, pear-shaped organ. Once egg is fertilized it finishes its development in uterus attached to uterine wall

Female Reproductive System 4. Urinary bladder – storage of urine 5. Urethra – passage of urine to outside of body 6. Vagina (birth canal) – leads to outside of body 7. Cervix – narrow neck of uterus 8. Rectum – passage for wastes

The Menstrual Cycle What is the menstrual cycle? Cycle during which an egg develops and is released from the ovary and the uterus is prepared to receive a fertilized egg Menarche: first menstrual period – usually occurs between 11 and 12 Menopause: time when a woman stops menstruating, usually between 45 & 55 and is no longer able to conceive.

The Menstrual Cycle

The Menstrual Cycle 1. Menstruation: Loss of egg and uterine tissue via vagina if fertilization does not occur 2. Follicle Stage (follicular stage): lasts 10 days, FSH & LH levels increase, egg matures, follicle secretes estrogen to prepare uterus

The Menstrual Cycle 3. Ovulation: High level of estrogen detected by hypothalamus, increased LH, decreased FSH, follicle bursts – egg released 4. Corpus Luteum Stage (Luteal Phase): LH converts follicle to corpus luteum – secretes estrogen & progesterone. Progesterone prepares uterus. Increased progesterone keeps LH & FSH low

Another Way of Looking at Negative Feedback in the Female Reproductive System (Hormones of the Menstrual Cycle) Brain Pituitary gland FSH (causes egg to mature in follicle) LH (causes to egg to be let go = ovulation) ovary Estrogen (causes uterine lining to thicken & build up to prepare for egg) uterus Progesterone (helps maintain uterine lining)

Hormones of Menstrual Cycle What happens if fertilization occurs? Corpus luteum keeps producing progesterone to maintain pregnancy. After 5 weeks the embryo produces progesterone – this inhibits LH & FSH so no menstrual cycle What happens if fertilization does not occur? There is no implantation – the corpus luteum breaks down. Progesterone level drops, uterine lining breaks down – menstruation. FSH & LH are produced again – new cycle Average Menstrual Cycle is 28 days long

Ovulation to Implantation oviduct uterus egg from ruptured follicle cervix ovary follicle vagina sperm

Ovulation to Implantation Ovary – produces estrogen & progesterone – meiosis occurs & egg develops Egg matures in follicle of ovary Ovulation – egg released from follicle – may live for 24 hours - egg moves into fallopian tube by cilia

Ovulation to Implantation Events in fallopian tube Fertilization occurs here. Sperm lives 4-5 days (egg lives 1 day) Zygote undergoes mitosis & travels down fallopian tube within 6-10 days. Zygote is ready to implant into uterus.

Ovulation to Implantation Events in uterus Implantation – embryo implants/embeds into uterine lining & secretes hormone HCG to signal its arrival Cell Differentiation – cells divide by mitosis & become different due to gene expression. Different embryo parts will form.

Menstrual Cycle Animation

Sexually Transmitted Diseases (STDs) Definition: Disease spread from one person to another during sexual contact Types of STDs: gonorrhea, chlamydia, syphilis, genital herpes, HIV, trichomonas Reducing Risky Behavior a. Avoid sexual contact b. Avoid intravenous drug use

Child with gonorrheal infection in the eyes

Advanced syphilis

Genital herpes

Trichomonas Life Cycle

Method of Birth Control How does it Work? Abstinence Refrain from intercourse to prevent sperm from joining egg Sterilization Females – tubal ligation-fallopian tubes are cut & tied so egg can’t be fertilized & reach uterus Males - vasectomy – cut & seal off vas deferens so semen never has sperm in it (Permanent) Withdrawal Removal of penis from vagina before ejaculation occurs Condoms Sheath covering penis to prevent sperm from vaginal contact

Diaphragm/Cervical Cap Birth Control Diaphragm/Cervical Cap Fitted cup or cap that covers the cervix to prevent sperm from reaching egg Birth Control Pill Contain hormones estrogen & progestin to prevent ovulation Protects against pelvic inflammatory disease (PID), ovarian & endometrial cancer (1 pill daily for 28 day cycle) Patch (Ortho Evra) Skin patch worn on lower abdomen, butt, or upper body. Releases progestin & estrogen into bloodstream to prevent ovulation (wear for 3 weeks, not on 4th – menstruation) Depo-Provera Shot of progestin to prevent ovulation

Birth Control IUD Small plastic device placed in uterus containing copper or progesterone. Prevents sperm from entering uterus & prevents a fertilized egg from implanting (Can be worn for 1-10 years) Family Planning Charting of menstrual cycle & detection of physical symptoms to determine “safe” time to have sexual intercourse Morning-after Pill Not a regular method of birth control Take 2 doses of hormone pills 12 hours apart & started within 3 days after having unprotected sex. Prevents implantation