3. Factors of Development
Heredity - transmission of traits
from parents to offspring through
the genes
Environment – includes all the
conditions inside and outside an
organism that influence its behavior
3
4. STAGES OF HUMAN DEVELOPMENT
Prenatal period: from conception to birth
Infancy and toddlerhood: birth to 2 years
Early childhood: 2-6 years old
Middle/Late childhood: 6-12 years old
Adolescence: 12-18 years old
Adulthood – 18 - death (EARLY, MIDDLE,
LATE)
7. In the Beginning: MECHANISMS
OF HEREDITY
Human egg and sperm contains 23
chromosomes selected from the mother’s/
father’s 46.
The 46 chromosomes contain around
30,000 genes
7
8. In the Beginning (Cont)
The human egg and sperm unite, resulting
in a zygote which contains a complete set
of 46 chromosomes
The first 22 pairs of chromosomes are
called autosomes
The 23rd pair determines the gender of the
child and are called the sex chromosomes
8
9. Mechanisms of Heredity
The 23rd Pair of Chromosomes
Males carry XY
chromosomes—X from mother
and Y from father
Females carry XX
chromosomes—X from mother
and X from father
9
10. HEREDITY
When two gametes unite to form a zygote, they
give the new life a unique genetic makeup
10
Egg Sperm
(23 pairs of chromosomes)
46
CHROMOSOMES
11. BASIC UNITS
OF HEREDITY
GENE
Contains DNA, Deoxyribonucleic acid.
Genes determine inherited characteristics.
DNA carries the instructions that tell each cell in
the body what specific functions it will perform
and how it will perform them.
Est. 100,000 genes distributed among 46
chromosomes.
11
12. Mechanisms of Heredity
The child’s characteristics are determined
by the interaction of genes on the two
chromosomes in a pair
Each chromosome of a pair contains one
parent’s contribution to a specific trait
When the genes are the same they are
called homozygous; when different, they
are called heterozygous
12
13. Mechanisms of Heredity
Homozygous Genes
When genes are the same, both of the
child’s parents have contributed
similar genes for a trait
Heterozygous Genes
The parents have contributed different
versions of the trait
13
14. Twins
Dizygotic (fraternal) twins come
from two different eggs fertilized
by two different sperm
Monozygotic (identical) twins
come from the union of one egg
and one sperm that splits in two,
soon after conception
14
15. Paths from Genes to Behavior
Heredity and environment interact
throughout development
Environmental influences typically
make children within a family
different
15
16. Period of the Zygote/Germinal Stage
(Weeks 1-2)
After fertilization, the zygote travels
down the fallopian tube and is
implanted in the uterine wall
As zygote passes down the fallopian
tube it separates into an outer
(placenta, umbilical cord and
amniotic sac) and inner layer (new
human being)
16
Periods of Prenatal Development
17. 17
The period of the zygote spans 14 days that begin with fertilization of the egg in the fallopian tubes and end with
implantation of the fertilized egg in the wall of the uterus.
18. 18 18
Period of the Embryo (Weeks 3-8)
Body structures, internal organs, and
the three layers of the embryo
develop:
- Ectoderm – outer layer of skin, nails, hair,
teeth, sensory organs & nervous system
- Mesoderm – inner layer of the skin,
muscles, skeleton, excretory and
circulatory systems
- Endoderm - digestive and respiratory
systems, liver, pancreas and salivary
glands
Periods of Prenatal Development
19. 19 19
Period of the Embryo (Weeks 3-
8)
The amniotic sac fills with
fluid and the umbilical cord
connects the embryo to the
placenta
Periods of Prenatal Development
20. Periods of Prenatal Development
Period of the Fetus (Week 9-
Birth)
Week 9- Differentiation of the
ovaries and testes
Week 12- Circulatory system begins
to function
Week 16- Movement felt by mother
Week 32- Age of viability
20
21. General Risk Factors
Nutrition
Inadequate maternal nutrition may
result in premature birth and low
birth weight
Stress
Studies show extreme maternal
stress is associated with low birth
weight and premature births
21
22. General Risk Factors
Mother’s Age
Older mothers are more likely to
have difficulty getting pregnant,
miscarriages, and stillbirths
Nearly 50% of pregnancies among
women in their 40’s and 50’s result
in miscarriage
22
23. Teratogens
agents, such as chemicals and
viruses, that can reach the
embryo or fetus during prenatal
development and cause harm
23
24. Teratogens: Environmental Hazards
Lead, Mercury, X-Rays
Effects may include mental
disability, retarded growth,
cerebral palsy, impaired memory
and verbal skill, retarded
growth, and leukemia
24
27. INFANCY – birth to two weeks
The period of the newborn
The shortest period of development
Subdivisions:
1. Period of the Partunate – birth to 15-30
minutes after birth
2. Period of the Neonate – cutting and tying
of the umbilical cord to 2 weeks
27
28. INFANCY – birth to two weeks
Adjustments to:
- Temperature changes
- Breathing
- Sucking and swallowing
- Elimination
28
29. Toddler/Babyhood Stage – 2 weeks to 2 years
Age of rapid growth and change
True Foundation age – many behavior patterns,
attitudes and emotional expressions are
established
Age of decreasing dependency
Age of increased individuality
Beginning of socialization
29
30. Childhood stage
1. Early Childhood – 2 years to 6 years
• Problem /troublesome age due to
development of distinctive personalities
• Toy Age
• Preschool age
• Exploratory age/Creative age
• Questioning age
• Pregang age
30
31. Childhood stage
2. Late Childhood – 6 years to 12 years
• Problem/Troublesome age (due to influence
of peers, sibling quarrels)
• Play Age
• Elementary School age
• Gang age
• Age of Conformity
• Critical period in the Achievement Drive
31
32. Adolescence - 12 to 18 yrs.
A transitional period
A Period of Change – Pubertal changes
Problem Age
Time of Search for Identity
Threshold of Adulthood
Time of Unrealism
32
33. Adulthood
Early – 18 to 40
- Reproductive age, settling down age, time of
value change
Middle - 40 to 60
- Time of achievement and evaluation, time of
empty nest
Late – 60 to death
- Period of Decline
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