Human Development

1. Human Development REPRODUCTION: Reproductive Systems Fertilization Pregnancy

2. The Human Reproductive System Reproduction is the process by which living organisms produce others of their own kind. Human life results from the union of two cells: one from the male and one from the female. These cells are produced by structures in the male and female reproductive systems and merge in the female during sexual intercourse The human reproductive system consists of body organs and structures that make it possible to produce young.

3. The Male Reproductive System The function of the male reproductive system is to produce sperm and transmit them to the female reproductive system. Sperm are the male reproductive cells. They are first produced during puberty which begins in boys between 10-12.

4. The Male Reproductive System

5. The Female Reproductive System The female reproductive system has four main functions: • It produces the hormones estrogen and progesterone • It stores and releases female reproductive cells, called eggs or ova • It allows fertilization to take place. • It nourishes and protects the developing child until it is able to survive outside the female’s body.

6. Parts of the Female Reproductive System

7. The Menstrual Cycle Ovulation may start as soon as a girl reaches puberty. Generally, this is between the ages of 8-12 although some girls can ovulate for the first time, also known as menarche, as early as 8 or as late as 16. After Ovulation, • If fertilization occurs, the lining of the Uterus, also known as the Endometrium, will develop further and nourish the fertilized egg. • If fertilization does not occur, which is what usually happens, the Uterine lining and un-used egg dissolve and mix with a small amount of blood. The body sheds the lining through the vagina. This is known as menstruation

8. The Menstrual Cycle (cont’d.) Menstrual flow stops after about 5 days. Ovulation: A mature egg is released from the ovary into a fallopian tube. If fertilization has not occurred, the uterine lining begins to break down. Menstrual flow begins. Fertilization is most likely to occur during these days.

9. Fertilization Sperm entering the vagina travel through the uterus to the fallopian tubes.Fertilization takes place in a fallopian tube when a male sperm cell and a female egg cell unite. The fertilized egg then moves through the fallopian tube to the uterus, where it becomes implanted. In the uterus, the fertilized egg gradually grows and develops.

10. Fertilization

11. Fertilization continued

12. Development After Fertilization The human body begins as a single fertilized cell. The fertilized cell then starts to divide into a number of cells. These cells are referred to as an embryo. After about a week, the embryo attaches itself to the lining of the uterus. After the eighth week, the embryo is called a fetus. From the moment of fertilization until birth, the cells develop into tissues, organs, and body systems.

13. Fertilization continued

15. The Developing Fetus 6 Months Length: 12 ½ inches Weight: 1 ½ pounds Behavior: kicks, hears sounds Fertilization The union of the sperm cell with an egg cell forms an embryo 9 Months Length: 18–20 inches Weight: 7–9 pounds Behavior: eyes open, fingers can grasp, body organs and systems can work on their own 3 Months Length: 3 inches Weight: 1 ounce Behavior: begins to move

16. Length of pregnancy? Most people say “9 months” but in reality, it’s 10. A pregnancy lasts 40 weeks. Pregnancies are divided into 3 trimesters of about 13 weeks each (give or take)

17. Care During Pregnancy DO: • Eat healthful foods. • Have regular checkups. • Beware of infections. DON’T: • Smoke or use tobacco. • Drink alcohol. • Take any unnecessary drugs.

18. Heredity Certain traits are traits you have inherited from your parents. Structures within cells influence heredity. Chromosomes are threadlike structures that carry the codes for inherited traits. Each chromosome is divided into thousands of small parts called genes Children inherit genes for each trait from each parent.

19. Heredity (cont’d.) Embryo Egg cell Sperm cell Sperm cell 23 chromosomes 46 chromosomes 23 chromosomes

20. Sex = Gender 22 of the 23 pairs of chromosomes are numbered. The 22nd is lettered either XX or XY. Recall that ½ of your chromosomes come from your mom and ½ from your dad. Eggs are always X and Sperm can be either X or Y. IF an X sperm fertilizes an egg, it will be a girl. If a Y sperm fertilizes an Egg, it will USUALLY, be a boy XY = boy XX = Girl

21. Sex = Gender However, if a Y chromosome fertilizes and egg, sometime during the 1st trimester, a chemical is secreted that must travel around the developing embryo and reach the gonads (reproductive organs BEFORE they actually become reproductive organs) If the chemical reaches the gonads, the embryo will grow the parts of the male reproductive system. If ithe chemical does not reach the gonads, the developing embryo will become a girl

22. Genetic problems at birth? Genetic problems can cause serious disorders. Down syndrome, for example, is a genetic disorder in which a person’s cells have 47 chromosomes instead of 46. Such disorders can affect physical or mental development, or both. Genetic disorders may be mild or severe; a few are fatal.

23. Care During Pregnancy Again….it is EXTREMELY IMPORTANT to eat healthy and avoid drugs and get regular check ups while pregnant!!! Your baby’s entire future can be effected by what you do!