W1 neurodevelopment conception- week 8 Flashcards
3 stages of prenatal development
1 Pre-embryonic stage (Zygote)
˃ Fertilization of ovum by sperm
→ from day 0 to day 14
2. Embryonic stage (Embryo)
˃ Once zygote implants in uterus
→ from day 15 to end of 8th week
3. Fetal stage (Fetus)
→ from end 8th week until birth
(38-42 weeks = full term)
Embryonic stage time frame and neural development
weeks 3-8
All tissues/organs formed
nerve system develops in 3rd week
cell growth division and increase in number
more specialised cell type
neural tube formed
Formation of embryonic disk
- Endoderm: gut, liver,
pancreas and respiratory
system. - Mesoderm: muscles,
skeleton, excretory and
circulatory systems - Ectoderm: sensory
organs, hair, skin, nails
and the whole nervous
system (CNS + PNS)
Neural tube defects (NTDs)
open spina bifida and closed spina bifida is most common defects
anencephaly
Fetal development: Week 13-24
- Neurogenesis (generation of new nerve cells):
- Most neurons by 24wk
- Major regions of brain develop
- Eyes sensitive to light, reacts to sound
Fetal development: Weeks 25-38/40
- Size increases, lungs mature
- Rapid brain development
what are Teratogens
Substances or conditions that can
disturb development of an embryo /fetus
eg medication, smoking, alcohol, hypertension
impact depends on dose, combination, age and heredity
Sensitive period: prenatal
Limited time period in which a part of the body or behaviour is biologically prepared to develop rapidly
Period of organ differentiation
- cells becoming specialised
Neonates developing/ from when
Neonate = first 4 weeks after birth
Full term infant – from 37 weeks
All body structures, neurogenesis largely
complete
Adjusting to new enviornemnt
Neurologically immature. Still developing:
-Myelination
-Synaptogenesis
Pre-term births when and grades
Pre-term = born before 37 weeks
Degree of prematurity by gestational age:
- extremely pre-term from 23-28 weeks
- very pre-term 28-32 weeks
- moderately pre-term 32-36 weeks
-late preterm 36-37 weeks
A related indicator of development
Low birth weight = <2500g
Pre-term babies difficulties
*e.g. inattention, overactivity
*sensory problems
*motor coordination
*language delays
*intellectual difficulties
*emotional / behaviour
