Chapter 3 Understanding Human Development.
All mammals start life as a tiny fertilized egg. The human reproductive system is designed to produce gametes and bring them together through internal fertilization.
Hormones - Messengers in the human body. They travel through the bloodstream and cause certain cells to respond in specific ways. Several hormones regulate the reproductive system.
Puberty - The period when an individual becomes capable of sexual reproduction and develops secondary sex characteristics. Hormones change the body so that it becomes able to reproduce.
When Puberty Begins..
The pituitary gland, located at the base of the brain, starts to produce follicle stimulating hormone (FSH). FSH travels to the gonads and signals them to produce gametes. Other hormones help in the development and maintenance of secondary sexual characteristics.
Puberty in Males
When FSH reaches the testes it promotes the development of sperm-producing tubes in the testes and the development of sperm cells. Other cell in the testes start to produce Testosterone , which directs the development of secondary sexual characteristics-deeper voice, body hair, and broadening of the shoulders.

Puberty in Females
When FSH reaches the ovaries they are stimulated to begin maturing and releasing eggs. Generally one egg is released each month. FSH also stimulates the ovaries to produce Estrogen , which directs the development of female secondary sexual characteristics-body hair, deposits of fat in the breasts and hips. After the age of 45 to 50, a woman stops releasing an egg each month because her estrogen levels drop. This change in the hormonal cycle is known as menopause.
Copy Page 82 Male Reproductive Anatomy
Copy Page 84 Female Reproductive Anatomy
Make a table listing the Male Parts and their function.
Make a table listing the Female Parts and their function.
Starting Points Activity Page 79
Predicting Reproductive Trends Page 81. Drawing a line graph Page 591
Copy Page 83 Sperm Development.
Page 83 Answer the Pause and Reflect
More about Females:
Ovaries are about 3cm in length and one egg or ovum
(plural ova) is released by the ovary approximately every

28 days. The two ovaries generally alternate, or take turns, releasing an egg.
Ovulation
The surface of the ovaries contains many fluid filled cavities called follicles. Each follicle contains an egg.
During ovulation, a mature egg breaks out of its follicle.
The feather ends of the oviducts, or Fallopian tubes, help guide the egg into the tube. Hair like structures lining the oviducts keep the egg moving towards the uterus. The egg can only survive for 24 to 48 hours after ovulation, unless fertilized. .
Sperm Development
Sperm are produced from the cells in the walls of the semniferous tubules. Diploid cell (46) are forced away from the tubule walls by mitosis. These cells undergo meiosis to produce mature sperm. The entire process of sperm production takes 9 to 10 weeks.
Menstrual Cycle
Before and after ovulation, the female reproductive system undergoes changes in a cycle that last approximately one month. The pituitary hormones tell the ovaries what to do and the ovarian hormones tell the uterus what to do.
Luteinising hormone (LH) is released by the pituitary gland. Progesterone is released by the ovary.

Progesterone comes from the corpus luteum a structure formed from the follicle after the egg is released.
The Female Hormones.
1. Pituitary Releases FSH
2. FSH stimulates follicles to develop.
3. A developing follicle releases estrogen.
4. -Estrogen stimulates the lining of the uterus to thicken
-Estrogen also travels to the pituitary stimulating the pituitary to release LH.
5. LH causes the developing follicle to release a mature egg (ovulation)
6. LH stimulates the empty follicle to develop into the corpus luteum.
7. Corpus Luteum produces progesterone and estrogen.
8. -Progesterone increases the thickening of the uterine lining.
-Progesterone cause the pituitary to decrease production of FSH and LH preventing more egg cells from being released.
9. If the egg is not fertilized, The corpus luteum breaks down, reducing progesterone in the bloodstream.
Declining progesterone levels cause the uterine lining to break down. The lining, consisting mainly of dead cell and blood, is shed form the body in the process know as menstruation. Menstruation lasts for four to seven days.
As the levels of progesterone decrease to a certain level, the pituitary gland will begin to produce FSH again.

Page 90 Check Your Understanding
Questions 1, 2, 4, 5, 6.
Page 106 Reviewing Key Terms
1 (only those with section 3.1)
Page 106 Understanding Key Concepts
5, 7, 8, 10.
Page 99 Fetal Development Activity Rulers Required!!!
Page 100 Risk Factors during Fetal Development.
Pregnancy
Sperm move through the uterus and into the oviducts.
Fertilization occurs in the oviducts. Only 1 sperm will fertilize the egg. After fertilization, the zygote continues down the oviduct toward the uterus. On its way, it begins the process of mitosis. The zygote undergoes a series of rapid cleavages or cell divisions. When it reaches the uterus, it has become a mass of cells arranged to form an almost hollow ball of cells called a blastocyst. The outer cells of the blastocyst will form the placenta, the inner cells will form the embryo.
Implantation
The embryo attaches itself to the thickened lining of the uterus in a process called implantation. This occurs six to ten days after fertilization. At this point pregnancy begins. The attached embryo produces a hormonal signal that prevents the corpus luteum form disintegrating. The corpus luteum continues to produce progesterone. This Keeps the uterine lining in place, which means there is no menstrual flow. The corpus luteum

produces progesterone for approximately the first 3 months of pregnancy.
Page 92. Outside Link
What is IVF?
What percentage of couples are not able to conceive a child?
When are the embryos transplanted into the uterus?
Page 92 Off the Wall.
Summarize and Answer the question.
Page 92 Did you know?
Summarize.
Embryo Development
When the embryo is in the blastocyst stage, its cells are mostly similar to each other. Then, cells begin to specialize to form a gastrula, in a process called gastrulation. The cells of the embryo become arranged into distinct layers called germ layers.
The cells move to specific positions to form three layers called the endoderm, mesoderm and the ectoderm.
* Draw and label the germ layers on page 93 at the top of the page.
Supporting Tissues
The outer portions of the embryo develop four important tissues:
1. The yolk sac supplies nutrients to the embryo for the first two months.
2. The amnion forms a fluid filled sac around the embryo.
3. The allantois helps remove waste from the embryo.
4. The chorion surrounds the embryo, yolk sac, amnion and allantois. It develops many finger like projections that extend

into the uterine wall to serve as kind of an anchor. Inside the fingers are blood vessels. Together, the blood vessels and chorion make up the placenta.
Once the placenta has formed, it takes over the yolk sac’s role in supplying nutrients to the embryo. It also maintains high levels of progesterone necessary to sustain pregnancy.
The embryo is attached to the placenta by the umbilical cord.
Sketch the tissues supporting development of the embryo on the bottom of page 93.
Differentiation and Birth.
Define Differentiation. Page 95
Pages 95 to 98 Describe the changes in the developing child during each Trimester.