Post on 29-Jan-2016
transcript
Chapter 4 Section 1The Developing Baby
ConceptionOvulation - 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.
ConceptionConception – the sperm fertilizing the ovumThe ovum usually lives 12 to 24 hoursThe sperm can lives 48 to 72 hoursDuring a normal menstrual cycle, there are 3-
4 days in which intercourse can lead to conception.
Ectopic PregnancyOccurs when the baby begins to grow
somewhere other than in the uterus, such as the fallopian tubes.
Dangerous for the motherDo not end in a live birth
GeneticsAt the moment of conception, every human
baby receives 46 chromosomesChromosomes come in pairs you get 23 pairs
totalHalf 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 GenesFor each inherited characteristic, a person
receives two copies of a geneOne from mother, one from fatherWhen both are the same, the child gets that
gene automaticallyDominant gene – a stronger gene
Controls the characteristicRecessive gene – a weaker gene
Not expressed
Making a Unique PersonGender determined at conceptionX chromosomes = female chromosomeY chromosomes = male chromosomeEvery woman has 2 X chromosomesEvery 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 BirthsNumber of children determined at conception
or soon afterMost common = twins
Twins3 in 100 births are twinsIdentical
One egg and one sperm divide into two cells4 in 1,000 births are identical twins
Fraternal Two eggs released into uterus at one time, get
fertilized by two different spermMay not look alike23 in 1,000 births are fraternal twins
Three or more birthsVery rare, but more likely if using treatments
to help women get pregnant.
InfertilityInfertility – the inability to conceive a child40% linked to women40% linked to men20% unknown causes, or linked to both
partners
Options for InfertilityAdoption – 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 husbandSperm 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 PregnancyGerminal Stage – fertilization of the egg
Embryonic Stage – development in 3rd – 8th week of pregnancy
Fetal Stage – From 8th/9th week until birth
Germinal StageCell 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
ImplantationZygote attaches itself to the side of uterus and
continues to growOnly the size of a pin head
Embryonic StageAmniotic Sac forms – Liquid that forms and
protects the babyPlacenta develops – Tissue that connects the
developing baby to the uterusFormed from special layers in the uterusRich in blood vessels that allow food and oxygen
to flow to the babyUmbilical cord develops – long tube that
connects the baby to the placentaTakes carbon dioxide and other waste products
away from the baby
Fetal StageVocal Cords DevelopDigestive system and kidneys begin to
functionSpontaneous moves are possible by the end
of the third month.Development is completingFetuses are very active in the fetal stageGrows to full termReady for birth