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The Reproductive System

The Reproductive System. Chapter 34 Ms. Luaces Honors Biology. 34.3 Sexual Development. Sex hormones determine the pattern of development Females respond to estrogens , which stimulate breast development, widening of the hips, and egg production

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The Reproductive System

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  1. The Reproductive System Chapter 34 Ms. Luaces Honors Biology

  2. 34.3 Sexual Development • Sex hormones determine the pattern of development • Females respond to estrogens, which stimulate breast development, widening of the hips, and egg production • Males respond to testosterone, which stimulates growth of facial hair, increased muscular development, and deepening of the voice • Most of these changes occur during puberty (ages 9-15) when the hypothalamus signals the pituitary to produce 2 hormones: FSH and LH

  3. 34.3 Male Reproductive System • Testosterone stimulates puberty, which will result in the ability to reproduce through the production of sperm

  4. 34.3 Male Reproductive System • Some important structures: • Testes: site of sperm production • Scrotum: holds the testes • Seminiferous tubules: site of sperm development • Epididymis: site of sperm maturation & storage • Vas deferens: merges with urethra, opening to release sperm • Semen: a mixture of sperm and lubricating seminal fluid

  5. 34.3 Female Reproductive System • FSH stimulates ovaries to produce egg cells and prepares the female’s body to nourish a developing embryo • One ovary usually produces and releases 1 mature ovum every 28 days: menstruation

  6. 34.3 Female Reproductive System • Some important structures: • Fallopian tubes: Where the egg is released into and awaits a sperm for fertilization • Uterus: Where the growing embryo will develop • Cervix: The opening to the uterus • Vagina: Entrance into the female reproductive system; egg and uterine lining will be discarded through here

  7. 34.3 Female Reproductive System • Menstruation is split into 4 phases: • Follicular phase: Pituitary secretes FSH & LH, stimulates estrogen release and causes the lining of the uterus to thicken (~12 days) • Ovulation: releases an egg into the fallopian tube for fertilization (~1-2 days) • Luteal Phase: Corpus luteum continues to release estrogen and progesterone, growing the uterine lining in prep for an embryo (~6 days) • Menstruation: unfertilized egg, lining of uterus and blood are discarded (~5-7 days) • Menopause: the permanent stop of the menstrual cycle at about age 40

  8. Sexually Transmitted Diseases (STD’s) • 1 in 4 girls age 14-19 are infected with an STD, which can include: • Bacterial STD’s: Chlamydia, Gonorrhea and Syphilis • Viral STD’s: Hepatitis B, Genital Herpes, Genital Warts (HPV) & AIDS • How do you prevent an STD? Abstinence is the only 100% effective method. Condoms cannot completely guard from STD’s!!

  9. 34.4 Fertilization & Development • The fusion of a sperm and egg cell is called fertilization • Usually occurs in the fallopian tube • Once fertilization occurs, the fertilized egg is called a zygote • Two eggs can be fertilized at the same time by different sperm – fraternal twins • One egg can be fertilized and split into two separate zygotes – identical twins

  10. 34.4 Fertilization & Development • About 6-7 days after fertilization, the blastocyst attaches to the wall of the uterus – known as implantation • Now it undergoes differentiation (gastrulation) – various types of tissue of the body are formed, including ectoderm, endoderm, and mesoderm. Eventually, neurulation takes places also (making of the nervous system)

  11. 34.4 Fertilization & Development • The placenta will protect and nourish the embryo, allowing exchange of oxygen and nutrients with the mother • Mother and baby blood do not mix

  12. 34.4 Fertilization & Development • After 8 weeks, the embryo is now called a fetus. • Most major organs fully formed • During months 4-6, the fetal heart becomes large enough to hear through a stethoscope, the bone develops, and the mother may be able to feel the baby

  13. 34.4 Fertilization & Development • During months 7-9, the fetus matures, gains weight, and completes the development of lungs and the nervous system • Babies born before 8 months are premature and may have breathing problems

  14. 34.4 Fertilization & Development • Childbirth is signaled by the release of the hormone oxytocin, which stimulates contractions of the uterus and starts labor • Once the cervix is open, the baby is able to pass through the birth canal • A babies first cough or cry helps to rid the lungs of fluid. The umbilical cord will be clamped and cut

  15. 34.4 Fertilization & Development • The placenta and amniotic sac will also be dispelled after birth • Prolactin hormone will be released and stimulate the production of milk • AIDS, Rubella, drugs, alcohol and smoking can harm the babies development

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