Biology Chapter on Ovulation and Fertilization

Study Notes

Ovulation is the release of a mature ovum from the ovary, traveling to the fallopian tube.
Fertilization occurs when sperm unites with the ovum.
Pregnancy is the development of an offspring in the mother’s womb.

Menstrual cycle signifies puberty onset in females.
Cycle is the monthly process leading to menstruation if pregnancy does not occur.
Cycle duration is measured from the first day of one period to the day before the next, typically lasting around 28 days (can vary from 21 to 40 days).
Ovulation generally takes place 10-16 days before the next menstrual period starts, regardless of the cycle length.

Fertilization happens in the fallopian tube where the sperm meets the egg.
The fertilized egg travels to the uterus, forming an embryo.
The embryo implants in the uterine lining (endometrium), marking the beginning of pregnancy.
Pregnancy duration ranges from 37 to 42 weeks, calculated from the first day of the last menstrual period.
Divided into three trimesters, each with distinct developmental milestones.
After eight weeks, the embryo is identified as a fetus.

Teenage pregnancy adversely affects education, social life, and economic opportunities.
Early parenting often leads to reduced chances of completing high school and pursuing higher education.
High school dropouts struggle to compete economically.
While teen pregnancy rates declined over the past two decades, they have recently stabilized.
Teens are still engaging in sexual activities, leading to ongoing pregnancy issues.

Calendar Method: Predicts ovulation days through a menstrual cycle calendar; effectiveness estimated at 85% theoretically but closer to 60% in practice.
Birth Control Pills: Contain synthetic estrogen; alter the ovulation cycle. Effectiveness is 99-100% if taken correctly; must be taken daily throughout the menstrual cycle.
Withdrawal: Involves the male removing the penis before ejaculation to avoid sperm entering the vagina; effectiveness around 85% but often lower in practice.
Male Condoms: Rubber sheath fitted over the penis; effectiveness between 80-85%. Provide STD/STI protection; avoid oil-based lubricants to prevent tears.
Implantable Hormone Device: Offers continuous hormone release; effectiveness is about 99%. Lasts 5 years (3 in the Philippines) and requires a medical procedure.
Birth Control Injection: Administers hormones (e.g., Depo-Provera) with 94-99% effectiveness; reduces menstrual cramps, requires doctor administration.
Intrauterine Device (IUD): T-shaped device inserted into the uterus; effectiveness is 95-98%. Long-lasting and affordable but requires medical insertion.
Sterilization: Involves vasectomy for males and tubal ligation for females; provides 100% effectiveness if performed correctly. It is a permanent method with a one-time expense.