Transcript Chapter 4.1 PPT

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
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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)
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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
 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
 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
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third month.
Development is completing
Fetuses are very active in the fetal stage
Grows to full term
Ready for birth