Chapter 4 Section 1 The Developing Baby

Conception Ovulation - About every 28 days, an ovum (egg cell) is released by one of a woman’s two ovaries. Menstruation Cycle When ovum is released from ovary, it moves through the fallopian tube into the uterus. Takes about 2-3 days When it reaches the uterus, it usually breaks up and leaves the body with the menstrual flow. When a sperm reaches the fallopian tube, it may penetrate and fertilize the ovum.

Conception Conception – the sperm fertilizing the ovum The ovum usually lives 12 to 24 hours The sperm can lives 48 to 72 hours During a normal menstrual cycle, there are 3-4 days in which intercourse can lead to conception.

Ectopic Pregnancy Occurs when the baby begins to grow somewhere other than in the uterus, such as the fallopian tubes. Dangerous for the mother Do not end in a live birth

Genetics At the moment of conception, every human baby receives 46 chromosomes Chromosomes come in pairs you get 23 pairs total Half from mother, half from father Per pair: 1 chromosome from father’s sperm, 1 chromosomes from mother’s egg = 2 chromosomes = 1 pair Each chromosomes has hundreds of thousands of genes No two people, besides identical twins, have identical DNA.

Dominant and Recessive Genes For each inherited characteristic, a person receives two copies of a gene One from mother, one from father When both are the same, the child gets that gene automatically Dominant gene – a stronger gene Controls the characteristic Recessive gene – a weaker gene Not expressed

Making a Unique Person Gender determined at conception X chromosomes = female chromosome Y chromosomes = male chromosome Every woman has 2 X chromosomes Every male has 1 X and 1 Y chromosomes At conception, the woman automatically gives X, so father determines sex (based on if he gives X or Y chromosome) XY = Male XX = Female

Multiple Births Number of children determined at conception or soon after Most common = twins

Twins 3 in 100 births are twins Identical Fraternal One egg and one sperm divide into two cells 4 in 1,000 births are identical twins Fraternal Two eggs released into uterus at one time, get fertilized by two different sperm May not look alike 23 in 1,000 births are fraternal twins

Three or more births Very rare, but more likely if using treatments to help women get pregnant.

Infertility Infertility – the inability to conceive a child 40% linked to women 40% linked to men 20% unknown causes, or linked to both partners

Options for Infertility Adoption – A couple is legally taking on all responsibilities and rights for raising, loving, and caring for a child in need of a permanent home. Artificial Insemination – Doctor injects sperm into a woman’s uterus. Procedure timed to take place when a woman’s ovary releases an ovum. Sperm is often from the woman’s husband Sperm donor can be used

Options for Infertility In Vitro Fertilization – Process used to treat many causes of infertility, such as when a woman has damaged fallopian tubes. Under microscope, the doctor combines a mature ovum from the woman with sperm from her husband and places it in the woman’s uterus. Pregnancy occurs if the fertilized egg attaches itself to the uterus Ovum Transfer – This procedure is similar to in vitro fertilization, except an ovum has been DONATED by another woman. Then fertilized in lab, and put inside of the woman.

Options for Infertility Surrogate Mother – A woman who becomes pregnant to have a baby for another woman. This option requires legal arrangements be made for everyone involved, including the child. THINK: Baby Mama! All options are very expensive and often medical insurance does not cover the costs, or covers very little of the costs.

Three Stages of Pregnancy Germinal Stage – fertilization of the egg Embryonic Stage – development in 3rd – 8th week of pregnancy Fetal Stage – From 8th/9th week until birth

Germinal Stage Cell Division Implantation Zygote begins to grow by cell division while in fallopian tubes One cell multiplies until there are hundreds of cells Takes about 4 days to reach the opening of the uterus Implantation Zygote attaches itself to the side of uterus and continues to grow Only the size of a pin head

Embryonic Stage Amniotic Sac forms – Liquid that forms and protects the baby Placenta develops – Tissue that connects the developing baby to the uterus Formed from special layers in the uterus Rich in blood vessels that allow food and oxygen to flow to the baby Umbilical cord develops – long tube that connects the baby to the placenta Takes carbon dioxide and other waste products away from the baby

Fetal Stage Vocal Cords Develop Digestive system and kidneys begin to function Spontaneous moves are possible by the end of the third month. Development is completing Fetuses are very active in the fetal stage Grows to full term Ready for birth