Chapter 2: Prenatal Development And The Birth Process Flashcards
What is pre natal and post natal development and importance thereof
Prenatal development: development before birth
Postnatal development: development after birth.
Research shows that numerous prenatal and birth related factors influence the later psychological development of individual.
Not only the individual but also society could be affected personally and emotionally on a legal ethical and religious level.
Explain the concept of conception
Conception Or fertilisation occurs when the male sperm cells penetrate the female egg cell which occurs 280days before birth.
The egg and sperm cells are called gametes/ sex cells.
The fertilised egg cell is called a zygote.
Explain what chromosomes genes DNA and RNA are.
A normal human zygote contain 46 chromosomes (23 pairs)
A chromosome is made up of segments called genes which are regarded as the smallest units of heredity and are carriers of human hereditary characteristics.
Chromosomes and genes consists of DNA ( deoxyribonucleic acid) which is the chemical basis for heredity as it carries info that serves as blueprint for particular chemical function that a cell had to fulfill.
DNA has a helical shape.
RNA ( ribonucleic acid)also called messenger RNA transfer the code from cell nucleus to cytoplasm and direct construction of protein.
Describe the dominance and recessivety of genes
Allele: a gene pair. One from each parent being homozygous or identical in terms of the characteristics they control the receiving person will show that certain characteristic.
When allele is heterozygous or different it will be dominant or recessive.
A dominant gene is a gene that dominants the other allele in determining phenotype which are the seen characteristics. When alleles are heterozygous person will always show characteristics of dominant gene.
The recessive gene is the one whose characteristics don’t become manifest.
Genotype: the underlying genetic makeup.
What are the prenatal stages
Prenatal period: period from conception to birth which is about 9 months long.
Divided into Germinal embryonic and fetal stages.
Discuss the Germinal stage
Period of zygote and begins with conception lasting for 1-2 weeks. Characterised by growth of zygote.
Implantation: the attachment of the zygote to the wall of the uterus. This marks end of Germinal stage.
Evaluate the embryonic stage
Lasts from implantation until 8 weeks after conception and organism is now an embryo which develop into 3 layers
Ectoderm: outer layer from which hair nails teeth sensory organs the outside layer of skin and nervous system develop.
The mesoderm: middle layer from which muscles skeleton the inside layer of skin the excretory and blood circulation systems develops.
The endoderm: inner layer from which digestive system liver pancreas sweat glands and respiratory system develop.
The umbilical cord which is the lifeline that connects embryo to placenta develops. This allows O2 and nutrients from mom to baby.
The placenta is a structure that grows on inner wall of uterus and supplies the oxygen and nutrients embyro needs while removing embryonic waste
During 3rd week blood vessels and stomach develop and a small tube that becomes the heart develop towards end of 4th week.
Comment on the fetal stage
Lasts from end of embryonic stage till birth. Organism recognised as fetus. 3months after conception sexual organs develop.
The seventh month is boundary between viability or non viability meaning between survival outside uterus or not.
Expand on prenatal environmental influences
Teratogen: any external factor or process that has a negative effect on the normal development of an unborn child.
Forms of teratogens
Time of exposure
Genetic vulnerability
The degree or intensity of the factors play a role.
Each teratogen has a different effect on the unborn child
Damage unnoticed at birth.
Describe the birth process.
Divided into 3 stages.
- Cervix dilates approx 10cm so baby can pass through.
- Begins when the baby’s head begins to emerge through the cervix and ends when baby is outside the womb.
- The placenta and attached membranes are expelled.
