Early Influences on Development - Prenatal Development Flashcards
Prenatal Development
list the 3 periods, 3 trimesters, & timeframes for prenatal development
periods
1) germinal period: conception to end of the 2nd week
2) embryonic period: 3 to 8 weeks
3) fetal period: week 9 through birth
trimesters
1) first trimester: week 1 to week 13
2) second trimester: week 14 to week 27
3) third trimester: week 28 through birth
Prenatal Development
characteristics of the germinal period
- zygote impants in the uterine wall
- exposure to toxic chemicals, drugs, or other teratogens typically have an “all-or-none” effect
- meaning that if exposure causes significant damage, implantation will not occur
- if implantation occurs, it suggests that exposure had little to no effect
Prenatal Development
characteristics of the embryonic period
- major organs & structures are forming
- exposure to teratogens is most likely to cause major defects
Prenatal Development
characteristics of the fetal period
- major organs & structures grow and msture
- exposure to teratogens is most likely to cause minor defects or abnormalities
- an exception is the central nervous system, which is susceptible to major damage from teratogens during both the embryonic & fetal periods
Prenatal Development
____ is the earliest age at which a premature baby can survive outside the womb and occurs between ____ and ____ weeks.
viability; 22 adn 26 weeks
Chromosomal Abnormalities
define & list 3 disorders due to a chromosomal deletion
a change in chromosome structure that involves the loss of one or more segments of a chromosome
- Prader-Willi Syndrome
- Angelman Syndrome
- Cri-Du-Chat Syndrome
Chromosomal Abnormalities
Prader-Willi
1. caused by a deletion on what chromosome
2. symptoms
- paternal chromosome 15
- symptoms include:
* narrow forehead
* almond-shaped eyes
* short statue
* small hands & feet
* poor muscle tone (hypotonia)
* global developmental delays
* chronic overeating (hyperphagia)
* obesity
* hypogonadism
* intellectual disabilities
* skin-picking & other self-injurious behaviors
Chromosomal Abnormalities
Angelman Syndrome
1. due to deletion on what chromosome
2. symtoms
- maternal chromosome 15
- symptoms include:
* small head & brain (microcephaly)
* wide jaw & pointed chin
* severe developmental delays
* communication & intellectual disabilities
* hyperactivity
* tendency to be unhappy
* ataxia
* seizures
* hand-flapping
Chromosomal Abnormalities
Cri-Du-Chat Syndrome
1. due to a deletion of what chromosome
2. symptoms
- chromosome 5
- symptoms range from mild to severe depending on the extent & location of the deletion & include:
* high-pitched (cat-like) cry
* low birth weight
* weak muscle tone
* characteristic facial features - widely set eyes, low-set ears, round face)
Chromosomal Abnormalities
list the 3 chromosomal disorders that are due to sex chromosome abnormalities
- Klinefelter Syndrome
- Turner Syndrome
- Rett Syndrome
Chromosomal Abnormalities
Klinefelter Syndrome
1. due to what chromosomal abnormality
2. effects males or females
3. symptoms
- the presence of 2 or more X chromosomes and a single Y chromosome
- males
- develop normal male identitiy but incomplete secondary sex characteristics and symptoms include:
- breast enlargement (gynecomastia)
- low testosterone
- disproportionately long arms & legs
- taller than normal
- delays in language development
- learning disabilities
- impaired problem-solving & social skills
Chromosomal Abnormalities
Turner Syndrome
1. due to what chromosomal abnormality
2. effects males or females
3. symptoms
- partial or complete deletion of one of the X chromosomes
- females
- don’t develop secondary sex characteristics & are infertile; symptoms include:
* short stature
* stubby fingers
* drooping eyelids
* receding or small lower jaw
* web-like neck
* learning disabilities
* heart defects
* kidney & urinary tract abnormalities
Chromosomal Abnormalities
Rett Syndrome
1. due to what chromosomal abnormality
2. effects males or females
3. symptoms
- X-linked dominant disorder that is usually caused by mutations in the MECP2 gene
- almost exclusively females
- infants appear to develop normally during first 6 to 18 months but then develop characteristic symptoms including:
* slowed head & brain growth
* loss of speech & motor skills
* abnormal hand movements
* sleep disturbances
* breathing abnormalities
* seizures
children with Rett Syndrom may also have autistic-like traits (e.g., deficits in social interactions) during early stages of the disorder
Chromosomal Abnormalities
Down Syndrome is a(n) ____ disorder. List the 3 types.
autosomal
1) Trisomy 21
2) Mosaic trisomy 21
3) Translocation trisomy 21
Chromosomal Abnormalities
The most common type of Down Syndrome is ____, which accounts for about ____% of all cases
trisomy 21; 95%
Chromosomal Abnormalities
The trisomy 21 type of Down Syndrome is due to the presence of what
an extra 21 chromosome in all cells of the body (each cell contains 47, instead of the usual 46 chromosomes)
Chromosomal Abnormalities
Mosaic trisomy 21 accounts for ____% of all cases of Down Syndrome and occurs when?
1%; only some cells in the body contain an extra 21 chromosome
Chromosomal Abnormalities
Translocation trisomy 21 accounts for ____% of all cases of Down Syndrome and is characterized by what?
4%; characterized by 46 chromosomes in all cells of the body with some cells having a full or partial chromosome 21 attached (translocated) to another chromosome (most often chromosome 14)
Chromosomal Abnormalities
list the symptoms of Down Syndrome
- intellectual disability (mild to moderate)
- decreased muscle tone (hypotonia)
- short stocky build
- wide face
- thick tongue
- almond-shaped eyes
- developmental delays
- an elevated risk for vision & hearing problems
- heart defects
- hypothyroidism
- Alzheimer’s
Chromosomal Abnormalities
in terms of etiology, which 2 types of Down Syndrome are caused by an error during cell division
trisomy 21 & mosaic trisomy 21
Chromosomal Abnormalities
what is the primary risk-factor of having a baby with trisomy 21
older maternal age (risk increases sharply after 30 years of age)
Chromosomal Abnormalities
translocation trisomy 21 is due to what?
either an error in cell division or inherited from a parent carrier
Genetic Disorders
Huntington’s Disease and Phenylketonuria (PKU) are ____ dominant disorders.
autosomal
Chromosomal Abnormalities
an autosomal dominant disorder means that these disorders are caused by what?
a single autosomal dominant gene
