Pregnancy & Menstruation

Menstrual Cycle once a month: 1 egg is released if the egg is not fertilized, it passes through the body and exits ends with menstruation lining of uterus is shed blood helps facilitate removal

Menstrual Cycle if the egg is “fertilized”, pregnancy begins instead of menstruation

Fertilization Sperm and Eggs have half the chromosomes of a normal cell, “haploid”

Structure of Human Sperm The head contains the HAPLOID nucleus with 23 chromosomes. The front of the head (acrosome) has chemicals that allow sperm to enter the egg

The mitochondria is located in the middle section and provides the sperm with energy. The whip-like tail propels the sperm

The Relative Size of Sperm and Egg The egg is larger than the sperm because it contains many nutrients to be used once the egg is fertilized.

Structure of Human Egg Support

The Structure of the Human Egg The egg has a haploid nucleus The egg has an outer barrier (Zona) that prevents more than one sperm from entering. It also has nutrient-producing support cells that surround the egg cell.

Fertilization Sperm must swim to egg If can get through outer layer of egg: the two nucleus’ fuse, making 1 cell with 2 half sets of chromosomes (or 1 full set!) this new, full cell: “zygote”

Development Fetus: “unborn baby” Baby: after birth Embryo Zygote 2+ cells Zygote One cell Fetus 8+ weeks old Abortion Question – when/what is aborted and removed. Fetus: “unborn baby” Baby: after birth

Pregnancy 40 weeks, from fertilization broken into 3 sections, “trimesters”

First Trimester fertilization to end of 3rd month embryo attaches to wall of uterus sac forms around, fills with “amniotic fluid” fluid supports & protects embryo/fetus placenta starts to form

Second Trimester 4th month to end of 6th month fetus grows A LOT! Can tell gender, with ultrasound

3rd Trimester organs function properly brain rapidly develops final developments happen for baby! before birth: fetus turns, so head is pointing down

To Do’s Words: - amniotic fluid -placenta menstruation -fertilization zygote -embryo fetus -baby testes -penis seminiferous tubules -urethra ovary -vagina uterus -oviduct