PSYC1001 Lecture Notes - Lecture 6: Fetal Alcohol Spectrum Disorder, Sexual Differentiation, Preterm Birth
Prenatal development
Nature and Nurture
• Prenatal development and environmental influences
Aims
• To introduce the stages of prenatal development
o Germinal period
o Embryonic period
o Fetal period
• To understand how genetic sequences of development are influenced by environmental factors
o E.g. The effect of teratogens
Prenatal development
• Development that occurs between conception and birth
• Begins:
o Fallopian tube - site of fertilisation
▪ Formation of single-celled zygote
o 266 days for single-celled zygote to become a 200 billion celled fetus
• Three periods:
o Germinal period
▪ From conception through implantation
▪ First 2 weeks
• Blastocyst - embeds into the uterine wall
• Single cell --> 16-64 cells
• Reaches uterus as a blastocyst
•
o Embryonic period
▪ 3rd week to 8th week
▪ Formation of major organs
• Highest risk of miscarriage
• Blastocyst implants in the uterine wall
• Layers of cells differentiate
• Forms different parts of the body
• Fetus attaches via umbilical cord and placenta
• Prevents infections
• Provides oxygen and nutrients
• Suspended in amniotic sac
•
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▪ 4 weeks
• Seahorse stage
• Eye, heart, liver, arm bud, tail (splits into legs)
• Develops crucial organs first
• Neural tube closes
• Top - brain
• Bottom - spinal cord
• Abnormalities in neural tube closure
• Anencephaly
• Top of neural tube does not form properly
• Develop without a brain
• Babies die within a few hours of birth
• Spina bifida
• Abnormality in closure of bottom of neural tube
• Part of spinal cord is visible
• May cause paralysis and movement issues
• Rare - standard recommendation to take folic acid
• Helps with formation of neural tube
• Heart begins to beat - 24 days
•
▪ 8 weeks
• Looks like a little human
• Facial features have been developed
• Beginning of sexual differentiation
• Cartilage in limbs become real bone
•
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Nature and nurture: prenatal development and environmental influences. Aims: to introduce the stages of prenatal development, germinal period, embryonic period, fetal period, to understand how genetic sequences of development are influenced by environmental factors, e. g. Prenatal development: development that occurs between conception and birth, begins, fallopian tube - site of fertilisation. Single cell --> 16-64 cells: embryonic period, 3rd week to 8th week, formation of major organs, highest risk of miscarriage, blastocyst implants in the uterine wall. Fetus attaches via umbilical cord and placenta: prevents infections, provides oxygen and nutrients. Fetus able to respond to light: able to hear sound. Sound level in the uterus is 75 db: mother"s voice and heartbeat. Limit of viability = 24 weeks: 50 % survival rate with technological aid, 7 months, third trimester, begins putting on weight in the form of fat, 8 months. Leg abnormalities: fetal period, physiological defects and minor structural abnormalities.
