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

9. Sexually Transmitted Diseases (STD’s)
1 in 4 girls age 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!!

10. 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

11. 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)

12. 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

13. 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

14. 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

15. 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

16. 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