Prenatal Development Flashcards
What happens during conception?
When 2 gametes are united/fused
Define gametes
Sex cells/reproductive cells
Contains half the genetic information of a male/female
What are the 2 types of gametes?
Sperm and egg
How are gametes produced?
Cell division (meiosis)
Meiosis involves taking only half of the genetic material of all other normal cells in the body
Where does fertilisation of the egg usually happen?
Fallopian tube
List the 4 steps to conception
1) Egg launches from the ovaries to the fallopian tube
2) As egg moves toward the uterus, it emits a chemical substance to signal sperm to its direction
3) After intercourse, 500 million sperm is ejaculated into the vagina
4) Sperm unifies with egg
What is the term used to describe a fertilised egg?
Zygote
What are the 3 periods of prenatal development?
1) Germinal
2) Embryonic
3) Fetal
When does the germinal period happen?
From conception - 2 weeks
When does the embryonic period happen?
From week 3 to week 8
When does the fetal period happen?
From week 9 to birth
At what prenatal period does the zygote
becomes implanted in the uterine wall?
Germinal period
At what prenatal period does rapid cell division take place?
Germinal period
When does rapid cell division take place during the germinal period?
As early as 12 hours after fertilization
Define mitosis
When the zygote doubles its number of cells roughly twice a day
At what prenatal period does the zygote perform mitosis?
Germinal period
What is the scientific term used to describe twins who are identical?
Mono-zygotic twins
What is the scientific term used to describe twins who are fraternal?
Dizygotic twins
How does the conception of monozygotic twins happen?
- When a single egg is fertilised by a single sperm but later on the zygote splits into 2
- Hence, the twins have the same genetic material as they came from the same cell
How does the conception of dizygotic twins happen?
- When 2 separate eggs are released from the ovaries and are fertilised by 2 separate sperm cells
- Hence, the twins have different genetic material as they came from separate cells
What is the term used to describe the results of the proliferation of cells?
Simply = When zygote keeps doubling (mitosis) until the zygote becomes a newborn with millions of cells
Cell division
What is the term used to describe the movement of cells from point of origin to other locations in embryo?
Cell migration
What is the term used to describe the transformation of stem cells into roughly 350 different types of specialized cell?
Simply = After continuous cell division, the cells start to specialise
Cell differentiation
What term is used to describe the selective death of certain cells (apoptosis)?
Cell death
Define apoptosis
When cells are genetically programmed to die based on a specific timeline
At which prenatal period does major development occur in all the organs and systems of the body?
Embryonic period
At which prenatal period does development take place through the processes of…?
- cell division
- cell migration
- cell differentiation
- cell death
Embryonic period
At which prenatal stage does the zygote turn into an embryo after multiple weeks of mitosis?
Embryonic period
What happens to the inner cell mass and the rest of the cell after the zygote performs multiple weeks of mitosis?
Inner cell mass becomes the embryo
Other parts of the cell become the embryo’s support system
What are the 2 types of support systems the embryo gets?
- Placenta
- Amniotic sac
What is the term used to describe a U-shaped groove formed from the top layer of differentiated cells in the embryo?
The neutral tube
What does the neutral tube eventually become?
It eventually develops into the brain and spinal cord
How does the neural tube become the brain and spinal cord?
One end of the tube will swell to become the brain and the rest of the tube becomes the spinal cord
When does the inner cell mass fold itself into 3 layers?
During the 2nd week
What are the 3 layers of the inner cell mass?
1) Top layer
- Nervous system
- Nails, teeth
- Inner ear
- Eye lens
- Outer skin
2) Middle layer
- Muscles
- Bones
- Circulatory system
- Inner skin
- Internal organs
3) Bottom layer
- Digestive system
- Lungs
- Urinary tract
- Glands
What term is used to describe a semi-permeable tube that allows the exchange
of materials between the bloodstream of the fetus and that of the mother?
Placenta
What is the purpose of the placenta?
It keeps the circulatory systems of the fetus and the mother separate but the semi-permeable membrane permits some material exchange (i.e. oxygen, waste, nutrients and CO2)
What term is used to describe the tube that contains the blood vessels that travel from the placenta to the developing organism and back again?
Simply = The tube that connects the fetus to the placenta
Umbilical cord
At which prenatal development period involves the continued development of physical structures and rapid growth of the body?
Fetal period
At which prenatal development period does the fetus receive antibodies from the mother in last month (particularly) of pregnancy?
Fetal period
At which prenatal development period does the fetus experience increasing levels of behaviour, sensory experience, and learning?
Fetal period
How long is the 1st trimester of pregnancy?
Week 1-Week 12
How long is the 2nd trimester of pregnancy?
Week 13-24
How long is the 3rd trimester of pregnancy?
Week 25-38
What term is used to describe the barrier that blocks against some, but not all toxins and infectious agents?
Placental membrane
What are the 2 components that protect the fetus?
1) Placental membrane
2) Amniotic sac
What term is used to describe a membrane filled with fluid in which the fetus floats, provides a protective buffer for the fetus and regulates temperature?
Amniotic sac
When does the fetus start spontaneously moving during prenatal development (at how many weeks)?
Around 5 weeks
When does the fetus start hiccupping during prenatal development (at how many weeks)?
At 7 weeks
Why does the fetus start hiccupping at 7 weeks?
- To practice a burping reflex (that they’ll use after birth to get rid of excess air)
- Prepares fetus for eventual nursing by removing air from the stomach to make more room for milk
When does the fetus start hand-to-mouth movements during prenatal development (at how many weeks)?
After around 18-19 weeks
What does the hand-to-mouth movement tell us about the fetus’ handedness?
If they often put their right hand in their mouth, they are most likely right handed
If they often put their left hand in their mouth, they are most likely left-handed
Explain what prenatal to postnatal continuity means
By 12 weeks after pregnancy, most of the
movements that have appeared during prenatal development will continue to be present at birth
Why does the fetus swallow amniotic fluid?
It promotes the normal development of the palate (tongue movement) and aids in the maturation of the digestive system
What does the movement of the chest wall and pulling in and expelling small amounts of amniotic fluid help the fetus with?
Helps the infants’ respiratory system become functional
Breathing in amniotic fluid allows the fetus to practice breathing in oxygen after birth
When does fetal breathing (breathing in the amniotic fluid) become stable?
During the 2nd half of pregnancy
Define circadian rhythm
The natural cycle of physical, mental, and behavior changes that the body goes through in a 24-hour cycle
It is affected by light and darkness
When do the fetus’s sleep and wake states become similar to those of the newborn?
Near the end of pregnancy
What are the types of sensations the fetus experience whilst they’re in the womb?
1) Tactile stimulation
2) Tastes and Smells of the amniotic fluid
How does the fetus experience tactile stimulation?
By grasping the placenta
How does the fetus develop taste and smell sensations?
By tasting and smelling the amniotic fluid
When does the fetus typically respond to sound?
From at least the 6th month of pregnancy
Who proposed that fetuses can actually see things whilst they’re in the womb?
Reid et al.
What did Reid et al. discover about fetal visual abilities?
Fetus shows a preference for faces (Top-heavy shapes), suggesting postnatal exposure is not necessary
When do fetuses start showing signs of decreased responses to repeated or continued stimulation?
At 32 weeks of pregnancy
When do fetuses start showing signs of habituation and dishabituation?
In the 9th month of pregnancy (30-32 weeks)
What is the term used to describe the environmental agents that have the potential to cause harm during prenatal development?
Teratogens
When do teratogens cause damage in prenatal development?
Depends on the timing and type of teratogen
Many agents cause damage only if the exposure occurs during a sensitive period in the development
When is the most sensitive/critical period?
a. Germinal
b. Embryonic
c. Fetal
b. Embryonic
In the embryonic period, when is the development of the CNS most sensitive?
Around 3-5 weeks of pregnancy
In the embryonic period, when is the development of the heart most sensitive?
Around 3.5-6.5 weeks of pregnancy
In the embryonic period, when is the development of the arms most sensitive?
Around 4.5-8 weeks of pregnancy
In the embryonic period, when is the development of the eyes most sensitive?
Around 4.5-8.5 weeks of pregnancy
In the embryonic period, when is the development of the legs most sensitive?
Around 4.5-8 weeks of pregnancy
In the embryonic period, when is the development of teeth most sensitive?
Around 6.5-12 weeks of pregnancy
In the embryonic period, when is the development of the palate most sensitive?
Around 6.5-13 weeks of pregnancy
In the embryonic period, when is the development of the external genitalia most sensitive?
Around 7.5-15 weeks of pregnancy
In the embryonic period, when is the development of the ear most sensitive?
Around 4.5-14 weeks of pregnancy
What term is used to describe when increased exposure to potential teratogens are associated with greater probabilities of fetal defects and more severe problems?
Simply = The greater the fetus’ exposure to a teratogen, the more likely it will suffer damage and the more severe the damage will be
Dose-response relation
What influences the effects of teratogens?
Individual differences
What makes it difficult to identify teratogens and their effects?
1) Their combination (difficult to pinpoint exactly what teratogens cause certain problems)
2) Sleeper effects (the problems derived from teratogens may be dormant until the child gets older)
What is the most human common teratogen?
Alcohol
What happens to the fetus when the mother consumes alcohol?
Fetal alcohol syndrome (brain injury)
How does alcohol get to the fetus during prenatal development?
Alcohol from the mother’s blood is exchanged through the semi-permeable placenta and into the fetus’ blood
What is the syndrome where maternal alcoholism causes delays in cognitive development, facial deformity, and other problems in children?
Fetal alcohol syndrome
What happens to the fetus when mothers smoke during pregnancy?
The fetus experiences reduced growth and low birth weight (reduced Oxygen)
Do e-cigarettes affect the fetus?
Yes.
The nicotine in the vape is a risk factor for fetal cardiac, respiratory, and nervous system development
What are the effects of smoking marijuana during pregnancy?
- Doubles risk of stillborn birth
- Memory, learning, attention, and impulsivity of the fetus is affected
What are the effects of doing cocaine during pregnancy?
- Fetal growth retardation, premature birth, attentional/arousal problems
- Withdrawal symptoms after birth
What are teratogens found in the environment?
- Pesticides
- Secondary smoker
- Pollution (air and noise)
- Herbicides
What happens to the fetus if they are met with environmental teratogens?
It affects their memory, learning, attention and impulsivity
What are occupational teratogens?
Teratogens that exist in the mother’s occupation
e.g. farmer (pesticide exposure), factory worker (chemical exposure), chemist (chemical exposure), nurse (disease exposure)
What are the teratogens that are related to nutrition?
- Folic acid/vitamin B = can cause spina bifida (when the skin around the spinal cord is not close enough) in the fetus
- Inadequate nutrients = can cause fetus to be nutritionally deprived at birth
What are the teratogens that are related to diseases?
- Rubella, STIs
- Flu = mothers who had the flu during the 1st trimester increases the risk of their fetus developing schizophrenia
- Zika
- Age (older/younger women are at greater risk of negative outcomes)
What is the term used to describe the infant’s level of arousal and engagement in the environment?
State
What are the 6 states of arousal
1) Active sleep
2) Quiet sleep
3) Crying
4) Active awake
5) Alert awake
6) Drowsing
On average, how long does the crying state last for in newborns?
2 hours
On average, how long does the active awake state last for in newborns?
2.5 hours
On average, how long does the alert awake state last for in newborns?
2.5 hours
On average, how long does the drowsing state last for in newborns?
1 hours
On average, how long does the active sleep state last for in newborns?
8 hours
On average, how long does the quiet sleep state last for in newborns?
8 hours
What type of sleep is this? (REM or non-REM)
An active sleep state associated with dreaming in adults and is characterized by quick, jerky eye movements under closed lids
REM sleep
What type of sleep is this? (REM or non-REM)
A quiet or deep sleep state characterized by the absence of motor activity or eye movements and by regular, slow brain waves, breathing, and heart rate
Non-REM sleep
Why do infants spend 50% of their sleep time performing REM sleep?
1) REM helps with infants’ visual system (due to high levels of internal brain activity that make up for infants’ lack of visual stimulation)
2) Jerking during REM helps infants build sensorimotor maps
What does the auto-stimulation theory suggest about REM sleep?
Brain activity during REM sleep in fetuses and newborns makes up for the natural deprivation of external visual stimuli and facilitates the early development of the visual system
Does non-REM sleep increase or decrease with age?
Increase
Does REM sleep increase or decrease with age?
Decrease
In early infancy, why do infants cry?
Crying reflects discomfort or frustration
In later infancy, why do infants cry?
Crying gradually becomes more of a communicative act
With experience, parents become better at interpreting the characteristics of the cry itself
What does infant mortality mean?
Death during the first year after birth
What is the term used to describe death during the first year after birth?
Infant mortality
What affects the rate of infant mortality?
Poverty and lack of health insurance
What is the term used to describe infants weighing less than 5.5 pounds (2,500 grams)?
Low birth weight infants (LBW)
What is the difference between premature and low-birth-weight infants?
Premature = born before 37 weeks after conception
LBW = Weight under 5.5 pounds
What makes an infant premature?
If they were born before 37 weeks after conception
What is the term used to describe when an infant’s birth weight is substantially less than normal for their gestational age?
Small for Gestation Age (SGA)
How can the negative effects of low-birth-weight infants be reduced?
Extensive parent contact and more touch for infants in neonatal intensive care
AKA “kangaroo care” to increase attachment
What are the complications that low-birth-weight infants face?
- Frequent illnesses
- Lower IQ score than expected for their age
- Lower educational achievement than expected for their age
What are the possible causes of low-birth-weight infants?
1) Teratogens (alcohol, smoking, drugs)
2) High rate of twin, triplet and multiple births as a result of increasingly successful treatments for infertility
What is this an example of?
Born in 1989 after just 27 weeks of gestation, Madeline weighed a mere 9.9 ounces
Low birth weight infant
What can help parents to take proper care of their low-birth-weight infant?
Educational programs designed to help parents with LBW babies learn about their revised developmental milestone timetable
Parents benefit from understanding that their LBW infants’ development will not follow the same timetable as that of a full-term infant
Gametes contain…
A. Twice the amount of genetic material of other cells in the human body.
B. Unique genetic information.
C. Half the amount of genetic information of other cells in the human body.
D. Teratogens which can damage embryonic development.
C. Half the amount of genetic information of other cells in the human body.
Which of the following is NOT a prenatal
developmental process?
A. Cell division
B. Cell migration
C. Cell differentiation
D. Cell accumulation
D. Cell accumulation
Which period of development takes place in the 3rd – 8th week of pregnancy?
A. Germinal phase
B. Zygotic phase
C. Embryonic phase
D. Fetal phase
C. Embryonic phase
Mary is 4 weeks pregnant and worried about the effects of teratogens on the development of her baby. The influence of teratogens is…
A. The same for all teratogens at every stage of development.
B. Subject to sensitive periods within pre-natal development.
C. The same for all fetuses.
D. Apparent from birth.
B. Subject to sensitive periods within pre-natal
development.
