Chapter 3- Pre and Postnatal Development Flashcards
How is heritability expressed?
As a positive number ranging from 0 to 1.0. Indicating the genetic variance associated with an estimate of variance in a phenotypic trait within a specific population
Epigenetic changes affecting health, brain growth and stress responses are positive or negative?
Can be either
Fertilization typically takes place in ________ and implantation occurs at ______ weeks.
A fallopian tube; implantation at approximately 2 weeks
Implantation- When does it start, when is it fully implanted, what are the terms to describe it?
- Starts at around 6 days postfertilization
- By 2 weeks, it is fully implanted
- The fully implanted zygote is called an embryo
Early Divisions
- First division at 2 hours
- Day 4= morula (16 cells)
- Day 5= outer and inner cells differentiate (outer cells will be placenta, now blastocyst)
- Day 16= gastrulation (ectoderm, mesoderm, endoderm)
Gastrulation
Gastrulation is the formation of the archenteron (digestive system), starts in the blastocyst with the formation of the blastopore
Neurulation
Neural streak, neural tube, nervous system
What are the four developmental processes that transform a zygote into an embryo and then into a fetus?
- Mitosis: Cell division resulting in two identical daughter cells
- Cell migration: Newly formed cells move away from point of origin
- Cell differentiation: Cells start to specialize in structure and function (and establish specialized reservoirs of stem cells)
- Apoptosis: Genetically programmed death of cells not required/necessary
Mitosis
Cell division resulting in two identical daughter cells
Cell migration
Newly formed cells move away from point of origin
Cell differentiation
Cells start to specialize in structure and function (and establish specialized reservoirs of stem cells)
Apoptosis
Genetically programmed death of cells not required/necessary
The earliest stage of development is
The germinal stage
Put the stages of development in order:
- Embryonic stage
- Terminal stage
- Fetal stage
- Germinal stage
- Germinal stage (first 2 weeks after conception)
- Embryonic stage (weeks 3 to 8)
- Fetal stage (week 9 to birth)
- Terminal stage (late stage development prior to birth)
Describe the process of the embryo differentiating
After implantation, the inner cell mass becomes the embryo.
The neural tube is a U-shared groove formed from the top layer of differentiated cells in the embryo, which becomes the brain and spinal cord. On day 24-25, there is a primitive brain forming.
What does the neural tube give way to?
The brain and spinal cord.
What is the neural tube formed from?
The top layer of differentiated cells in the embryo.
When does the primitive brain form?
Day 24-25
When do neural tube defects occur?
When the neural tube fails to close properly.
- 1 in 1,000 births is affected by a clinically significant neural tube defect
- Occurs in the 3rd-4th weeks of pregnancy
In the US, the FDA in 1996 authorized that all enriched cereal grain products be fortified with folic acid, with optional fortification beginning in March 1996 and mandatory fortification in January 1998. Why was this considered a “successful intervention”?
Th folic acid supplementation was directly correlated to lower levels of anencephaly and spina bifida (Due to fewer neural tube defects from a lack of folic acid in the diet).
Key Points- Embryonic Period
- Large changes in body structure
- Large changes in size
- Cells are differentiating, migrating to form major structures
- Weeks 3-8
- Embryonic face development proceeds rapidly from 5 1/2 to 8 weeks
Key Points- Fetal Period
- Weeks 9 to birth (38 weeks gestation, 40 weeks past last period)
- Rapid growth; most weight gain is in the last two months
- By 22 weeks, some can survive with neonatal intensive care
- By 28 weeks, fully developed lungs, some can survive without medical support, many can develop essentially normally with support
- Cephalocaudal and proximodistal development patterns
At what week are the lungs fully developed?
28 weeks
Fetal growth, experience and behavior
- Neurogenesis essentially complete at 18 weeks
- Spontaneous movement in embryonic stage at 7 weeks as limbs develop increasing movement
- Tactile sensations, kinesthetic sensations, taste, smell, hearing, memory
- Habituation to sound, learning specific patterns, music
