prenatal development Flashcards
the three stages of prenatal development
zygote
embryo
fetus
the conception stage does?
continuation from conception and when we don’t know exactly when conception is we us an estimation from when the persons last period was.
when deciding the conception date what do we add
we add 2 weeks
conception
you should begin planning 3 months before you want to become pregnant.
- (you want to get off of contraceptives 3 months before wanting to be pregnant)
- the body should also be getting healthy
the period of the zygote
- lasts about 2 weeks from fertilization
‣ Fertilization typically occurs within whichever fallopian tube it goes into
parts of the period of the zygote
◦1) Duplication - 30 hours for the first duplication
◦2) blastocyst - 4th day made of 60-70 cells
‣ A) embryonic disk - inner cells
‣ B) trophoblast - protective covering and nutrition for the organism
◦3) implantation - between day 7 and 9
‣ Egg will implant into the uterine lining
* If it happens too early you can run into an ectopic pregnancy when the zygote implants onto the outside of the uterus instead of the inside. Often it is not compatible and does not make it.
the period of the embryo
- implantation through the 8th week of pregnancy
◦Development of the embryonic disk occurs - the inner cells of the blastocyst
‣ Endoderm becomes - (gut) digestive system, liver, pancreas, lungs (inner layers)
‣ Mesoderm becomes - circulatory system, lungs (epithelial layers), skeletal system,
muscular system
‣ Ectoderm becomes - hair, nails, skin, nervous system
- implantation through the 8th week of pregnancy
neural tube formation
◦Ectoderm folds over to produce a primitive neural tube
‣ Super essential part of our development
◦At this stage the embryo is at high risk for issues
neural tube development - cleft lip/palate
‣ When there is an issue with growth at the top cleft lip appears.
‣ Cleft palate causes people to be susceptible to a lot of things. You can’t suckle from a
bottle or breast. When they do feed the baby can aspirate their food into their passages
and into their lungs/respiratory system. Everything from your nasal passages like phlegm
and mucus will drip into the mouth.
neural tube development - spina bifida
‣ A problem at the bottom causes spina bifida. It is when there is not a proper closure at
the bottom. Depending on how far it is from the bottom determine how severe it is.
* Some people may not have bladder control, some may have a lot of pain and others
no pain, and some may become paralyzed.
◦Can do surgery on this while the baby is in utero. This is pretty risky but can be
effective.
‣ Most neural tube defects at the top or bottoms can be neutralized with
adequate amounts of folic acid in the diet.
organ formation in the period of the embryo
- Heart pumping
- Organ formation
◦At the end of the first month, the curled embryo consists of organized cells with specific functions, but is only 1/4 inch long
- Organ formation
‣ Weeks 3 & 4: heart and embryonic blood vessels begin to develop, embryonic circulation is established, the heart begins to beat, cardiac looping is completed
‣ Week 5: partitioning of the heart into 4 chambers begin
‣ Week 6: aortic arches undergo primary changes to the adult form
‣ Week 8: formation of the heart valves is complete
the second month of pregnancy - embryo
◦Eyes, nose, jaw and neck form (but no bones yet)
‣ A. Limb buds
‣ B. Intestines grow
‣ C. Heart develops chambers
‣ D. Liver and spleen produce blood cells
‣ E. Basic sensation - responds to touch on mouth and soles of feet- at the end of the
second month is more upright 1/7 ounces and 1 inch long
* Spontaneous miscarriages will still happen (most still wont have announced thy are
pregnant)
third month of pregnancy - embryo
◦A. Organs communicate one another
◦B. Lungs expand and contrast
◦C. Kicking, toe curling, opens mouth, thumb sucking
◦D. External genitalia by week 12
◦E. Fingernails, tooth bud, eyelids
‣ We will start calling it a fetus now (partially because it is starting to look like a baby)
when do we start calling a baby in utero a fetus
after the third month
the period of the fetus
the second trimester 4-6 months
‣ Most neurons in place
‣ Sensitive to sounds and light