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Introduction to the Reproductive System
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Female Reproductive System
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1. Ovaries Main sex organ in females Size and shape of an almond
Life time supply of eggs-350,000 in each ovary. Only use 400 to 500 in a lifetime. Oogenesis: process of making Eggs in the ovaries. At puberty one egg every month finishes maturing and is released from the ovary -
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Ovaries (continued) B. Produces Hormones:
A. Estrogen- development of sex characteristics: -enlarges reproductive organs -breast development -increased fat deposits Widening of pelvis Onset of menstrual cycle Vascularization of skin
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Ovaries (continued) B. Progesterone (pregnancy hormone)
-vascularization of uterus -maintains the pregnancy -prepares breast for milk production
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2. Fimbrae -Funnels egg into fallopian tube -Doesn’t touch the ovary
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3. Fallopian Tube -Leads the egg to the uterus (takes 5 days)
-Egg and Sperm meet here!!!
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4. Uterus a.-Triple lining -Endometrium: blood layer
-Myometrium: muscle layer -epimetrium: skin layer b. Receives, retains and nourishes fertilized egg c. Size and shape of pear, can increase greatly
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5. Cervix Opening between uterus and vagina
Common site of cancer: Get yearly Pap smears
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6. Vagina -Birth canal (8-10 cm long)
-Behind the urethra and in front of rectum -Receives erect penis, sperm released Covered by a hymen that may be thick or thin.
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7. External Parts A. Vulva surrounds the opening of the urethra
and vagina Labia majora and minora -folds of skin that protect the external organs B. Clitoris: corresponds to the penis erectile tissue, engorges with blood, glands for lubrication
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8. Breast -secretion of milk Size does NOT affect function
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MENSTRAL CYCLE 1. Days 1-5 (can be up to 7 days) Menses (period)
Endometrium (blood layer) is released causing bleeding Blood passes through vagina Lose 50 to 150 mL of blood (1/4 to ½ cup)
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2. Days 6-14 Hormones in the brain signal the release of FSH (Follicle stimulating hormone) that causes an egg in the ovary to mature. Estrogen (made in the ovary): Rebuilds endometrium Increases in amount until
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3. Day 14 OVULATION Estrogen causes the pituitary to release the hormone Leutenizing Hormone (LH). This causes the rupture of the follicle in the ovary and an egg is released.
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Days The progesterone (made in the ovary) is released to help keep the woman pregnant if the egg gets fertilized. A. If NO fertilization- Hormone levels go down Cycle returns to Day 1
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B. If egg IS fertilized- The embryo secretes a hormone( progesterone) to keep the corpus luteum maintained.
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Bottom Line for pregnancy
The egg lives 24 hours Sperm live 48 to 72 hours Sperm need 1-2 hours to get to the egg To get pregnant- you must have intercourse no more than 72 hours (3 days) before the egg is released and no later than 24 hours after the egg is released (ovulation)
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Days 11-15 are the days when a woman can get pregnant.
Many women do not have a 28 day cycle so this is NOT a good method of birth control. The onLy 100% method of birth control is ABSTINENCE!!
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Male Reproductive System
Produces, stores and releases sperm
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1. Testes -Main sex organ in men, outside of body in scrotum
-Makes sperm -Scrotum keeps temperature 3 degrees lower than body temp -Low temp needed to produce viable sperm
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1. Testes (cont) -Releases Testosterone, which controls these Male Sex Characteristics -deepening of voice -increase in hair all over body -enlargement of skeletal muscles -thickening of bones
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1. Testes (cont) Anatomy of the testicle Each section is divided into
Seminiferous Tubules (700 ft) Sperm are made in the tubules Spermatogenesis: making of sperm–takes days -Tubules connect to the epididymus
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2. Epididymus (20 feet) Found just outside the testes
In the epididymus sperm mature -cytoplasm trimmed off -tail grows acrosome forms on head of sperm (lysosome) Maturing takes 20 more days (84 to 92 days)
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3. Semen formed from three glands
A. Seminal Vessicle Attached to Vas Deferens -fluid that regulates pH, is energy rich (sugar), and stimulates muscle contraction in the female. (Why?) B. Prostate Gland -fluid that neutralizes acidic environment of vagina
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3. Semen formed from three glands (cont)
C. Bulbourethral Gland (Cowper’s) Lubricates the penis Cleanses urine left over First to pass through
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When male is stimulated sexually:
1. Epididymus contracts and releases sperm into… 2. Vas Deferens 45 cm long tube that brings sperm to urethra for ejaculation. As the sperm travels through semen is added
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When male is stimulated sexually:
3. Urethra Tube running through penis sperm released from this tube only urine or sperm can pass through at one time- NOT at the same time 4. Ejaculation 2-6 ml of semen 120 million sperm per ml Lives hours
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Problems with sperm production:
Environmental Antibiotics- decreases amount of sperm Radiation- deforms sperm Lead Pesticides Excessive alcohol Drugs Tobacco
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What will you be doing??? Research your assigned topic on embryology
Design a PowerPoint Presentation containing at least 10, but no more than 15 slides Your first slide should be a title slide including the stage of development you are covering and the group members. Check the rubric for more details!!!
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Click here to see a sample PowerPoint
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