2 - Biological foundations, genetics, prenatal development & birth

Learning objective: Genetic inheritance and the transmission of genetic differences Genotype: specific info we inherit Phenotype: traits actually exhibited by an individual Mitosis: process that ensures the duplicate cell is identical in genetic make-up to the original cell Meiosis: process of reduction and division which halves the number of chromosomes 23 chromosomes from mother and 23 from father Dominant gene: influences the phenotype Recessive gene: needs to be paired with another recessive gene to be seen in phenotype Polygentic traits: transmitted through combined action of several genes

Learning objective: How genetic abnormalities occur & what responses can be made Downs Syndrome: extra 21st chromosome, risk increases as woman gets older (36+) Sickle-cell disease: recessive gene disorder; circulatory/oxygen issues due to shape of red blood cells Haemophilia: blood clotting, x-linked, genetic and sex-linked Huntingtons's disease: gradual deterioration of CNS, causing uncontrollable movement, mental deterioration, death Cystic fibrosis: difficulties in breathing & digestion, delayed growth & sexual maturation, vulnerability to infection, short life expectancy Congenital heart disease: abnormalities of the heart Neural tube defect: spine tube fails to close completely, brain absent or underdeveloped. Death of sever intellectual impairment. Cleft lip/palate: causes diff. in breathing, speech, hearing, eating. ResponsesGenetic counselling and prenatal diagnosisCultural factors may influence decisions: collective vs personal autonomy, directive vs non-directive

Learning objective: The joint influences of genetics and environment Range of reaction: a range of possible phenotypes an individual with a particular genotype might exhibit in response to the specific sequence of env. influences experienced. Identical twin and adopted children studies show that both heredity and env. jointly influence developmental change

Learning objective: Prenatal development & risksPrenatal Development Conception - zygote formed by sperm and egg combining and consists of discrete periods (stages) Germinal - 1st 2 wks - zygote forms a blastocyst and embeds Embryonic - 3 - 8 wks - placenta, umbilical cord form and basic organs and and bio. systems begin to develop Foetal stage - 9 - end - all physical complete Risks Infertility - unable to conceive after a year of trying Critical periods - usually during 1st trimester where embryo can be affected by teratogens Drugs, (medical and non-medical), diseases (gonorrhoea, AIDS, syphillis), other hazards

Learning objective: The birth process Labour - Stage 1 - contractions up to 10cm wide cervix Labour - Stage 2 - dilation complete and birth takes place Labour - Stage 3 - delivery of placenta

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