The Reproductive System

Why do we have a reproductive system?

1. To produce hormones that regulate growth, development and sexual behavior

2. To produce sex cells (sperm & egg)

3. To reproduce offspring

MALE REPRODUCTIVE SYSTEM

Function of Male Reproductive Parts

• Testis: location of where sperm are produced; located outside the body

• Scrotum: muscle that contacts or relaxes to make the most suitable environment for sperm production (2-3O different than main body)

• Seminiferous tubules: tubules in the testes where sperm develop

• Epididymis: structure on top of each testis where sperm mature and are stored

• Vas deferens: duct through which sperm move away from the testis and toward the urethra

• Urethra: tube that conducts semen and urine out of the body though the penis in males and transports urine out of the body in females

• Semen: fluid that contains sperm, nourishment and male reproductive fluids

• Prostate gland: produces alkaline (base) solution to contribute to the semen fluid; to neutralize acidic conditions sperm might encounter in the urethra or female reproductive tract

http://www.youtube.com/watch?v=8DoARSlv-HU

Male Sexual Hormones

Gonadotropin-Releasing Hormone (GnRH)

Follicle-Stimulating hormone (FSH)

Increases the production of FSH and LH

Promotes the production of sperm cells in the testes

Luteinizing Hormone (LH)

Testosterone

Stimulates the production and secretion of testosterone in the testes

Influences the development of secondary sex characteristics (ex. Wide shoulder, narrow hips, facial hair).

The pituitary gland is where GnRH, LH and

FSH are produced.

FEMALE REPRODUCTIVE SYSTEM

FEMALE REPRODUCTIVE SYSTEM

Function of Female Reproductive Parts

• Vagina: part of female reproductive system between the uterus and the outside opening; birth canal

• Cervix: neck of the uterus, which opens to the vagina

• Uterus: saclike muscular organ where embryos develop

• Endometrium: inner lining of the uterus, richly supplied with blood vessels that provide the maternal part of the placenta and nourish the developing embryo

• Fallopian Tube: tube that transports an egg released from an ovary to the uterus

• Ovary: location where egg cells (oocytes) are produced and stored

Egg Development• All eggs female have exist

from birth in an immature form called oocytes; they are located in the ovaries

• Ooctytes get nurtured in ovaries with fluids called follicles

• Average, once every 28 days 1 follicle-oocyte complex ruptures and releases an egg into the fallopian tubes

Egg development

• A woman is born with about 1 – 2 million oocytes in her ovaries.

• Throughout her life, the vast majority of oocytes will die.

• When a woman reaches puberty and starts to menstruate, only about 400,000 oocytes remain.

• Every 28 days 1 oocyte will MATURE into an egg (ovum) and be released for fertilization. About 1,000 oocytes are lost during this process.

How many mature eggs (ovum) will develop during a female’s life?

Approximately, 400 eggs

How many years will a female be able to reproduce? Approximately, 30 years

Menstrual Cycle• Menstruation: dismantling and shredding

of the uterine environment; which is the release of blood, fluids, mucus and endometrium tissue

• Length of cycle varies from 23 – 35 days, but typically lasts 28 days.

• Cycle is divided into three phases1. Flow phase2. Follicular phase3. Luteal phase

Menstrual Cycle Phases

Menstrual Cycle PhasesFLOW PHASE

• Fertilization and implantation of an embryo did not occur.

• Outer layers of endometrium tear away.

• Shedding of blood, epithelial tissue, fluid and mucus.

• All hormone levels are low

Menstrual Cycle PhasesFollicular Phase

• A few follicles begin to mature in the ovary. Inside each follicle is an immature egg – the oocyte. The follicle produces estrogen

• After 7 days only one of the follicles remain

• FSH and LH levels peak causing the follicle to rupture and release the egg into the fallopian tube.

• The release of the egg is know as ovulation.

Menstrual Cycle PhasesLuteal Phase

• Follicle is transformed into a structure called the corpus luteum.

• Corpus luteum produces high amounts of progesterone.

• When the corpus luteum breaks down, progesterone levels decrease; it triggers detachment of the endometrium

• Then the flow phase begins again…

What if the egg gets fertilized?

• New menstrual cycle does not begin

• Progesterone levels remain high and increase blood supply to endomedtrium

• Corpus luteum does not break down

• Endometrium accumulates lipids and begins secreting nutrient fluids for the developing embryo

https://www.youtube.com/watch?v=kV_EOEihudk

Menstrual Cycle Activity Images of figure #1 show the different the stages that occur during the menstrual cycle if fertilization does not occur.

Cut out the images and match them to Calendar #1.

Images of figure #2 show the different stages that occur during the menstrual cycle if fertilization does occur.

Cut out the images and match them to Calendar #2.

fertilization

zygote

morula

blastocyst

embryo

first trimester

vulnerable

growth

heartbeat

third trimester

fat

Embryo Development

Fetus Development

Birth!

There are there stages of birth1. Dilation2. Birth3. Expulsion

Dilation• Walls of uterus begin to contact

• Opening of the cervix

• Amniotic sac tears (“water breaking”)

Birth• Cervix fully dilated to 10cm• Mother contracts abdominal

muscles to help push baby• Once baby is out umbilical cord is

clamped and cut

Expulsion of Placenta

• Placenta detaches from uterus• Mother pushes one last time

Human Reproductive Technology

1. Artificial Insemination2. In vitro fertilization (IVF)

3. Gamete intrafallopian transfer (GIFT)

4. Surrogate mothers5. Fertility drugs

• What are 3 causes of infertility for men?

• What are 3 causes of infertility for women?

• Compare procedures of IVF and GIFT.

Prevention of Pregnancy

Contraceptive Methods

Method% of Women Experiencing Unintended Pregnancies

Perfect Use Typically Use

Abstinence 0 0

Birth control 0.1 5

Vasectomy 0.1 0.15

Tubal ligation 0.2 0.5

Rhythm Method 1-9 20

Withdrawal 4 19

Condom (male) 3 14

Diaphragm & spermacide

6 20

Spermacide 6 26

Morning After Pill: Treatment initiated within 72 hours after unprotected intercourse reduces risk of pregnancy by at least 75%

Contraception is the deliberate prevention of pregnancy. Without contraception, there is an 85%

chance.