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Human Development

By Edith Ramos,2014-04-12 14:31
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Human Development

    Human Development

    Forming a New Life / The Prenatal Period

Fertilisation or conception, is the process by which sperm and ovum - the male and

    female gametes, or sex cells -combine to make a single cell called a zygote, which

    then duplicates itself again and again by cell division to produce all the cells to make

    up a baby” (Papalia, Olds & Feldman. 2009, p54)

Mechanisms of Heredity

    The science of genetics is the study of heredity. (inborn factors inherited from the biological parents that affect development).

The Genetic Code the basic unit of heredity is DNA

     deoxyribonucleic acid (Bases ATGC form the genetic code)

    -genes: small segments of DNA, functional units,

     found on the chromosomes

    -chromosome

     carry the genes

     each cell has 23 pairs (46) except gametes which have 23 chromosomes

     -3 billion base pairs constitute the genetic code which determines all inherited

     characteristics.

    Human genome: the complete sequence of genes in the human body

Specialised cells …gametes (sex cells)

    female gamete

     ovum (stored in the ovary)

     6 - 24 hours xx

    male gamete

     spermatozoa (produced in the testes)

     24-72 hours xy

Cell Division

    -meiosis

    -sex cell division to form gametes

    -ova spermatozoa -22 + 1 chromosome

     22 + 1

    -xx - xy

     -mitosis cell division …two cells the same

    - monomorphic genes....human state

    - polymorphic genes…individual

    Determination of sex of the individual

     x y (male) (female) x xx xy

     x xx xy

Multiple Births

    -occur in 2 ways

    -monozygotic -one fertilised ovum splits very early

    - identical twins (maternal)

    -dizygotic (most common) -two ova are released

    -non-identical twins (fraternal)

    Patterns of genetic Transmission

    The study of genetics is the study of heredity

    ….the inborn factors, inherited from the biological parents that affect our development

    Gregor Mendal (Austrian Monk)

     example

    alleles Bb = alleles for blue eyes dominant genes B

    recessive genes b

    homozygous BB or bb

    heterozygous Bb

dominant inheritance BB or Bb

    recessive inheritance bb

    -phenotype: observable characteristics of a

     person

     -genotype: genetic makeup of a person,

     containing both expressed and

     unexpressed characteristics

    Genetic and Chromosomal Abnormalities

    Abnormalities may occur through mutation, inherited disposition, environmental

    influences or multi-factorial.

    dominant inheritance. eg. achondroplasia

    recessive inheritance. eg. Cystic fibrosis

    sex linked inheritance eg. Red / green

     colour blindness -Genetic Counselling

    can help assess parents risk of bearing children with a genetic birth defect

    -Karyotype

    Issues to discuss

     “Genetic testing and genetic engineering “

     reference (Papilia, Olds and Feldman, 2009 p67)

     issues:

    Human Cloning: -issues:

    Human Genome: -issues:

    Heritability

    Statistical estimate of the contribution heredity makes towards individual differences in a

    specific trait….within a certain population.

    -Family / kinship studies

-adoption studies

    -twin studies Questions / Comments

    The Prenatal Period and Environment

    germinal stage ( fertilisation - 2 weeks)

     organism divides….rapid cell division, increasing complexity , implants in the

    uterus…forms the placenta and the amniotic fluid.

embryonic stage ( 2 to 12 weeks)

     major body systems and organs develop.

     -Critical period / stage

     - teratogens

fetal stage (12 weeks - birth)

     increasing development ……...growth

     What do you think it would be like in the intra uterine environment?

The intrauterine environment

    placenta: delivers oxygen, nourishment, deals with elimination, helps maintain the pregnancy through hormone production

    umbilical cord: connected to the placenta

    amniotic sac and fluid: encases the fetus allowing room for movement, protection from outside and changes in temperature

    membranes: surrounds the fetus inside the uterus

     Stimuli include:

    Environmental influences

    Teratogens:

    capable of causing birth defects.

    depends on the timing of exposure

    intensity and co-interaction

    Father / Mother

    lead , marijuana , tobacco, alcohol, radiation, pesticides , chemicals , drugs of abuse,

    diet low in vitamin C.

    mother: medical drugs, nicotine, caffeine,

     infections :TORCH, HIV, Aids

Ways for a pregnant woman to create a healthy prenatal environment for her child to be

    include:

    Prenatal Assessment (not tested in this course but interesting to think about it in this context)

    -amniocentesis

    -chorionic villus sampling

    -embryoscopy

    -fetal movement, -fetal heart rate, -increase in abdominal size

Birth

    -gestation 266 days (9 months)

    -preterm (less than 37 weeks gestation) -term (37-42 weeks gestation)

    -post term (over 42 weeks gestation)

    The Newborn / neonate

    average weight: 3000gm / 7.1/2 lbs length : 45-50 cms / 18-20 inches long size at birth is related to: race, sex , parents’ size, mother’s nutritional status and health. -features:

    flexed body……..pink …….large head, small chin….nose breathers

    -heart rate 100-120 beats per minute -temperature control….immature….needs warmth from the environment

    -nose breathers until approx 3-4 months

-brain at birth 25% of adult weight…by age 12 years brain is full adult size.

    -Brain growth is moulded by experience especially during early life……

     implications?

    Fetal / newborn environments

     intrauterine / after birth

     nutrition: mother’s food and

     blood digestion

     respiration: placenta respirations

     stimulation: minimal much

     elimination: placenta G.I tract

Newborn reflexes

    -reflexes: involuntary, automatic responses to external stimulation

    -intact primitive pathways…neurological system

    -reflexes include :

     sucking, rooting , grasp, stepping, moro, babinski….

    -disappearance indicates the cortex is maturing

-growth: rapid …double weight by 4-5th month

    gross motor development:

     -sequence the same in all infants

     -wide variation to normal fine motor development -primitive.

Newborn / senses

    Vision:

     least dev. at birth

     focus approx. one foot away

     responds….bright lights, faces , reds

     and greens, curve lines to straight

     by 4 -5 months binocular vision.

    Touch: very sensitive to touch…feels pain

    Hearing:

     acute …responds mother’s voice, rhythmic noises

    Smell: responds to unpleasant odours, can identify mother’s smell.

    Taste: prefers sweeter to sour

    ? Implications for parents, nurses, to enhance optimal development

Theory to Practice

     What would Jean Piaget tell you about the best environment for a baby? Why?

     What would B.F. Skinner tell you about how a baby learns and therefore how you should behave?

What would Ivan Pavlov tell you how babies learn?

Albert Bandura would say……..

    Infant mortality

     -the Infant mortality rate (IMR) is the number of deaths occurring in babies in the first

    year of life.

    New Zealand ranks 22nd out of 25 industrialised countries

     (Papalia, Olds & Feldman 2009 p 111)

     causes for infant mortality include: SUDIS, sudden unexplained death of an infant,

     congenital anomalies and peri-natal conditions

    Sudden Unexplained Death of an infant (SUDIS) or “Cot (crib) death”

     - the sudden death of an infant under 1 year of age which the cause of death remains

    unexplained after a thorough investigation that includes and autopsy”.

     (Papalia, Olds & Feldman 2009 p 112)

     -? Combination of factors appear to explain why it happens

    -following on from international research the Ministry of Health in New Zealand promotes

    -“Back to sleep,” for sleep position

    -no smoking around the baby

    -breastfeeding

    -baby sleeping in own cot or bassinette.

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